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  • Other Sources  (7,599)
  • ASTROPHYSICS  (5,125)
  • INSTRUMENTATION AND PHOTOGRAPHY  (2,474)
  • Cell & Developmental Biology
  • General Chemistry
  • 1980-1984  (4,249)
  • 1975-1979  (3,344)
  • 1950-1954  (6)
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  • 1
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    Distortion measurement of antennas under space simulation conditions with high accuracy and high resolution by means of holography (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The use of laser holography for measuring the distortion of antennas under space simulation conditions is described. The subject is the so-called double exposure procedure which allows to measure the distortion in the order of 1 to 30/micrometers + or - 0.5 per hologramme of an area of 4 m diameter max. The method of holography takes into account the constraints of the space simulation facility. The test method, the test set up and the constraints by the space simulation facility are described. The results of the performed tests are presented and compared with the theoretical predictions. The test on the K-Band Antenna e.g., showed a distortion of approximately 140/micrometers + or - 5/micrometers measured during the cool down from -10 C to -120 C.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center 13th Space Simulation Conf.; p 309-319
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  • 2
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    RIMSTAR: Rapid image scanning technology and archiving (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Conventional schemes for digitizing large volumes of photographic data are far too costly and time consuming to encourage the undertaking of the ambitious projects using traditional technology. There is a distinct need for fast digitizing systems such as could be derived from development of large format, optically multiplexed CCD systems designed to address these problems. The use of CCD chips for data handling and the capability of using polaroids in the optical path for reduced light scattering are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 419-427
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  • 3
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    Photographic surveys of the southern sky (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Parameters of the UK 1.2 meter Schmidt telescope are described. Plates taken with this instrument are in two categories, those for systematic sky surveys and those taken at the request of research users. A collaborative project with the European Southern Observatory was undertaken to obtain a two-color survey of the sky south of -20 deg declination to complement the Palomar survey. A near infrared survey of the Galactic Plane and the Megallanic Clouds is being done. The area south of -20 deg and the zone between 0 deg and -15 deg are also being surveyed. Pending a decision on survey parameters, all available A quality prism plates are being retained to form a basis for systematic survey. Nearly half the plates taken on a service basis for the UK astronomical community are to fulfill nonsurvey requests. Plates taken for surveys which are not of A grade quality are also made available for research purposes.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 379-385
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  • 4
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    The preparation of the measurements at the PDS at the Padova Observatory: Report on an experience with the development of an astronomical data base environment (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Some software facilities used mainly for information retrieval and analysis at the Padova-Asiago Observatory are discussed. These facilities help guest and resident astronomers to make easier the preparation of plate measurements. The problems connected with the creation, use and management of a data base in a scientific (astronomical) environment are reviewed on the basis of the experience gathered during the last three years. The development plan of the user session environment and its possible applications in a computer network are briefly sketched.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 361-369
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  • 5
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    Plans for a fast image recording system at ESO (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A 256 diode-array will be installed as detector on the ESO OPTRONICS S-3000 measuring machine in order to increase the acquisition rate. A high intensity LED will be used as light source in a pulse mode. The data will be stored on a random access mass storage device as density values for later education. The scanning time for a 30 cm x 30 cm plate with a step size of 10 micron will be less than 10 hours while the dynamic range of the data is expected to be 2.5 density units with an offset of at least 1 unit.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 317-328
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  • 6
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    The automated photographic measuring facility at Cambridge (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The design and performance of the automated photographic measuring facility at Cambridge is described. It consists of a precision laser scanning microdensitometer connected to a series of computers that process the data on-line. Plates up to 350 mm square can be measured. The microdensitometer samples the plate to 12 bit accuracy at a speed of 230,000 samples/second. The positional accuracy is better than a micron. Other features include platen rotation and automatic focus.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 277-288
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  • 7
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    Techniques of isophotometry (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The expected performance of the Minnesota automated dual-plate scanner (APS) is discussed with regard to photometry, position measurement accuracy, and ability to classify images. In addition, a fast algorithm for calculating image parameters is described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 267-276
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  • 8
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    The current status and future upgrade of the PDS at the Royal Greenwich Observatory (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Various aspects of the performance of the PDS 1010A microdensitometer are described. The primary points in an upgrade propsal for the unit are outlined. Photometric instabilities in the PDS are mentioned.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 129-134
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  • 9
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    Microdensitometer electronics modification (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Minor modifications of electronic components in the PDS 1010A microdensitometer are discussed. The operational requirements and performance limitations of the PDS are noted. Replacement of the photomultiplier and front-end analog circuitry significantly improved the photometric performance of the PDS. The improvement in density repeatability is marked, and the permissible density slew speed is greatly increased.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 121-128
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  • 10
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    Performance testing of the high altitude observatory PDS microdensitometer (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: High Altitude Observatory HAO microdensitometer undergoes monthly testing to assure its consistent performance. These tests check positional and photometric stability at the 10 micron aperture level. The HAO test procedure is designed to run without operator intervention following initial configuration of the microdensitometer for each subprocedure. Specialized test software is resident in the PDP 8. The operator selects the proper subprocedure by entering commands. Once computer control is established, it is not relinquished until the test is complete.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Astron. Microdensitometry Conf.; p 19-34
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  • 11
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    Diagnosing a PDS microdensitometer (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A number of diagnostic tests are developed for the Photometric Data System PDS 2020G microdensitometer to monitor its performance and to isolate various electromechanical problems. A number of tests which help to diagnose problems with the photometer, positional accuracy and data collection are described. The tests include: (1) scanning a razor blade edge to study the response of the photometer and zero point losses in the coordinate system, (2) scanning a long straight line to evaluate the drunkness of the stage motions, (3) scanning photometric step wedge calibrations to study the response of the photometer, and (4) measurement of a series of high signal to noise plates of the same region of the sky to evaluate the overall performance of the microdensitometer. A variety of electronic tests to isolate electromechanical problems are also performed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 3-18
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  • 12
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    Ruled and holographic gratings experiment (A0138-5) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The behavior of ruled and holographic gratings with various coatings after extended exposure to the space environments was examined. The coatings and differentiating between the influences of vacuum and solar illumination were examined. In the past, several ruled and holographic gratings with various coatings were successfully flown on rocket experiments. Future utilizations of such gratings are considered for the Space Telescope and for various Spacelab projects under development. The techniques which is used to replicate gratings can also be used to obtain a wide range of lightweight optical components, including sophisticated aspherical, highly polished mirrors.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 163-164
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  • 13
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    Space debris impact experiment (S0001) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The specific objectives of this experiment are to establish the population and size distribution of meteoroids in the mass range from 10 to the minus 10 power to 10 to the minus 4 power G, to establish the current population of man-made debris in the same mass range, and to obtain data on the physical properties (composition and density) of meteoroids.
    Keywords: ASTROPHYSICS
    Type: Long Duration Exposure Facility (LDEF); p 136-137
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  • 14
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    Holographic data storage crystals for LDEF (A0044) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Electro-optic holographic recording systems were developed. The spaceworthiness of electro-optic crystals for use in ultrahigh capacity space data storage and retrieval systems are examined. The crystals for this experiment are included with the various electro-optical components of LDEF experiment. The effects of long-duration exposure on active optical system components is investigated. The concept of data storage in an optical-phase holographic memory is illustrated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 152-153
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  • 15
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    Interplanetary dust experiment (A0201) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The objective of this experiment is to study interplanetary dust, variously referred to as cosmic dust, cometary dust, zodiacial dust, or meteoric dust particles. Specific objectives are to obtain information regarding particle mass and velocity, and to undertake correlative analyses with other experiments, both on LDEF or near the time of the LDEF flight.
    Keywords: ASTROPHYSICS
    Type: Long Duration Exposure Facility (LDEF); p 134-135
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  • 16
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    Attempt at dust debris collection with stacked detectors (A0138-2) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The primary objective of this experiment is to investigate the feasibility of future missions of multilayer thin-film detectors acting as energy sorter to collect micrometeoroids, if not in their original shape, at least as fragments suitable for chemical analysis. It is expected that this kind of particle collector will help in solving one of the most puzzling topics in cosmic-dust studies: the mineralogical and chemical composition of the particles. This is a matter of great interest in the study of the origin and evolution of the solar system.
    Keywords: ASTROPHYSICS
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 124-126
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  • 17
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    Multiple-foil microabrasion package (A0023) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The specific scientific objectives of this experiment are to measure the spatial distribution, size, velocity, radiance, and composition of microparticles in near-Earth space. The technological objectives are to measure erosion rates resulting from microparticle impacts and to evaluate thin-foil meteor 'bumpers'. The combinations of sensitivity and reliability in this experiment will provide up to 1000 impacts per month for laboratory analysis and will extend current sensitivity limits by 5 orders of magnitude in mass.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 117-120
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  • 18
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    Computer simulation of the effects of transmission-averaging in microdensitometry (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: One of the principal advantages of electrography when compared to photography is the nearly linear relationship between source intensity versus resulting image density. This property allows for simplified and more accurate photometric calibration and permits a certain degree of extrapolation of the calibration to beyond the limits of the faintest photoelectric standard on an exposure. The desires to extract quantitative photometric information from electrographic (or photographic) negatives and to convert this information into a digital format for computer analysis or enhancement led to the widespread use of scanning microdensitometers to perform this A-to-D conversion. Therefore it is of vital importance to understand and, if practical, to avoid any nonlinearities which may be introduced during microdensitometry of electrographic emulsions.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 429-431
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  • 19
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    The role of the Automated Plate Measuring (APM) machine in developing a program to discover QSOs automatically (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The scanning of a direct plate with the automatic plate measuring machine which results in the automated selection and description of images is described. The selection of QSO candidates based on color-color diagrams constructed from the APM image data and the analysis of APM raster data for QSOs selected visually from objective prism plates are also discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 417-418
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  • 20
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    Next generation microdensitometer (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The fundamental limitations of microdensitometers are reviewed and the design of a high microdensitometer described. The system will digitize to 16 bits in transmission at a speed of 100 kHz using a laser beam moving over the emulsion. Other features are automatic platen rotation and autofocus. The cost will be of order $200,000.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 333-341
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  • 21
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    A new measuring machine in Paris (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A new photographic measuring machine is under construction at the Paris Observatory. The amount of transmitted light is measured by a linear array of 1024 photodiodes. Carriage control, data acquisition and on line processing are performed by microprocessors, a S.E.L. 32/27 computer, and an AP 120-B Array Processor. It is expected that a Schmidt telescope plate of size 360 mm square will be scanned in one hour with pixel size of ten microns.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 329-332
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  • 22
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    A preliminary analysis of a diode array for densitometry (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A diode-array based image digitizer manufactured by the Eikonix Corp. was tested to see if it can be adapted to the exacting requirements of astronomical densitometry. As the device is presently configured, a dynamic range of 400:1 can be achieved routinely, with a positional accuracy of 2 microns or better. An area of 2048 X 2048 pixels can be scanned in about 5 minutes. Preliminary tests indicate that several relatively simple enhancements can improve both the photometric and the positional accuracy of the device.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 307-315
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  • 23
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    A next generation microdensitometer? (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Motivations for construction of a next generation microdensitometer (NGM) are presented and their effect on the NGM design is discussed. A prototype of such an engine has been constructed at KPNO. Its design and performance is reviewed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 291-305
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  • 24
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    Why use a microdensitometer other than a PDS? (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The motivations for constructing a special purpose built microdensitometer are explored. The salient points of some of the microdensitometers are described and the advantages and disadvantages of the system in comparison to a PDS machine are outlined. The principal gain is in speed though at the expense of loss in dynamic range. The effects on the astronomical results are demonstrated. The astronomical results already obtained with these machines and from ongoing projects are described. It is shown that there is a large class of important astronomical problems which can be tackled by these machines but which are not feasibile on the PDS because of the speed of the machine.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 209-228
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  • 25
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    Improvements to the Photometric response and positional accuracy of the Yale PDS 2020G microdensitometer (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The necessity to incorporate several hardware changes to optimize the Yale PDS 2020G microdensitometer for photometric and astrometric research are discussed. The properties of a new high speed photometer and a positional calibration system are described. The new photometer incorporates a high speed logarithmic analog to digital converter with more than 10 times the resolution of the former system and a cycle time of approximately 50 usec. The positional calibration system monitors the drunkenness of the stages with respect to fixed index lines and enables the correction of the +/- 5 micro stage errors to an accuracy of better than 1 micro.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 151-161
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  • 26
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    Performance of the ESO PDS (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The astrometric and photometric performance of the PDS 1010A microdensitometer are discussed, including the tests used for checking it. The instrument was shown to satisfy operational requirements for photometric measurements of astronomical plates with respect to dynamic range and stability.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 89-95
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  • 27
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    Characteristics of the MSFC, PDS microdensitometer (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The results of several parametric studies carried out on the Marshall Space Flight Center (MSFC) Photometric Data System PDS-10 microdensitometer are summarized for the purposes of documenting the operation and limitations of the system for inhouse research and to provide a bench mark for comparison with other microdensitometers. The results are grouped into four general areas. These are: (1) system overall stability to drift, (2) photometric linearity and noise, (3) reproducibility, and (4) scanning performance. Test data taken in order to evaluate the interdependency of scan speed, noise and position are included. Shown also are results of tests for system stability, reproducibility, stray light and PMT settling time.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center Astron. Microdensitometry Conf.; p 71-88
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  • 28
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    Microdensitometer errors: Their effect on photometric data reduction (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The performance of densitometers used for photometric data reduction of high dynamic range electrographic plate material is analyzed. Densitometer repeatability is tested by comparing two scans of one plate. Internal densitometer errors are examined by constructing histograms of digitized densities and finding inoperative bits and differential nonlinearity in the analog to digital converter. Such problems appear common to the four densitometers used in this investigation and introduce systematic algorithm dependent errors in the results. Strategies to improve densitometer performance are suggested.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 45-58
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  • 29
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    Experiences with a PDS 2020 GM (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Various perturbations which occurred during the operation of a PDS 2020 GM microdensitometer are reviewed. The effects of elevated temperature, vibration, transient electrical noise, and photometric perturbations are briefly discussed. Sample astronomical results from the PDS 2020 GM unit are presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 97-106
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  • 30
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    Positive-feedback photometric drift in the PDS (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Digitizing flatfield images produces conditions in the Photometric Data System PDS which cause the measured density to drift by as much as .1 DN during a 10 minute interval. The drift occurs when the PDS, set up in equilibrium at fog level, subsequently scans a reasonably dense region for periods of longer than a few minutes. The drift is manifested primarily as a positive shift in density that is approximately the same for all densities. If the fog level is assumed to be in fact constant and is monitored during scans of flat fields, the PDS drift may be removed by subtracting the difference between the observed fog level and its assumed constant value for each pixel. This function is then smoothed and subtracted, as a function of scan line, from the measured density. The fog level is then adjusted to a standard value by adding a constant. The result is a flattened scan with PDS drift removed to the accuracy within which the fog level drift matches the drift at other levels.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Astron. Microdensitometry Conf.; p 59-69
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  • 31
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    Photometric and positional accuracy of the PDS Bonn in view of astronomical requirements (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The photometric and positional accuracy of a microdensitometer is examined. A calibrating plate with different density areas available is used to determine photometric accuracy. Position accuracy is evaluated by multiple scans of sharp edges and analyzed statistically.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 35-43
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  • 32
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    LDEF thermal measurements system (P0003) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Many of the passive experiments flying on LDEF will be significantly enhanced if data are available postflight to indicate the temperature time histories of test materials and other specimens exposed in the experiments. The baseline LDEF approach was to provide postflight calculated temperature histories of experiment boundaries and solar flux data for the mission, which can in turn be used by each investigator to calculate the temperature time histories for critical experiment components. Without in-flight temperature measurements, a substantial uncertainty will exist in the calculated temperatures. The data measured by the themal measurement system (THERM) will significantly improve postflight knowledge of temperatures experienced by LDEF experiments. The THERM data will also be valuable in validating the LDEF thermal design concept and in providing better design data for experimenters on future LDEF missions. The objectives of this experiment are to determine the history of the interior average temperatures of the LDEF for the total orbital mission and to measure the temperatures of selected components and thermal boundary conditions.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Long Duration Exposure Facility (LDEF); p 78-81
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  • 33
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    Interstellar-gas experiment (A0038) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The objectives of this experiment are to collect and isotopically analyze interstellar gas atoms around the orbit of the Earth for the purpose of obtaining new data relevant to understanding nucleosynthesis, and to study the dynamics of the interstellar wind inside the heliosphere and the isotopic composition of the interstellar medium outside the heliosphere. The experiment hardware will act as a set of simple cameras with high-purity copper-beryllium collecting foils serving as the film. The experiment housing will mount and thermally control the foils, establish the viewing angles and viewing direction, provide baffling to reject ambient neutral particles, provide a voltage grid to reject ionospheric charged particles, sequence collecting foils, control exposure times, and protect the foils from contamination during the deployment and retrieval of the LDEF. After being returned to Earth, the entrapped atoms can be analyzed by mass spectroscopy to determine the relative abundance of the different isotopes of helium and neon. An attempt will also be made to detect argon.
    Keywords: ASTROPHYSICS
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 98-100
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    High spatial resolution IR observations of young stellar objects - A possible disk surrounding HL Tauri (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: High spatial resolution images of the T Tauri star HL Tau were obtained at 1.6 microns and 2.2 microns. The original images as well as maximum entropy image reconstructions reveal a circumstellar envelope structure, similar at both wavelenghts, and extended along P.A. = 112 deg; the 10 percent width of the structure is 1.9 sec (300 AU at 160 pc). The extended structure is interpreted as light scattered toward earth by dust in a disk surrounding this young stellar object. Polarization measurements made at 2.2 microns support this hypothesis. The total solid particle mass is, at minimum, 5 x 10 to the -7th solar mass.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 283; L57-L61
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    Very slow classical Cepheids - Theoretical models with periods longer than 50 days (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Systematics of the light curves of classical Cepheids with the longest known periods have been investigated with the help of full-amplitude models of pulsating stellar envelopes. For periods exceeding about 60 days, flat-topped light curves of the S Vul type are found to replace the smooth, asymmetric light curves characteristic of the slightly faster Cepheids. Predicted light and velocity amplitudes (although not the predicted radius amplitudes) agree well with observations. Variables with fluctuating light minima are observed to lie well off the mean period-luminosity relation, as are a few other (more stable?) variables with similarly long periods. The explanation for the long periods is probably low effective temperature rather than a low stellar mass. Because of the abnormal slowness of the classical Cepheids with periods longer than about 100 days, it is recommended that these variables not be used to calibrate the mean period-luminosity relation. Analogies between the slow classical Cepheids and the slow Population II Cepheids are drawn.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 281; 811-814
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  • 36
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    On the '3 kiloparsec arm' - Resonance excitation of linear and nonlinear waves by an oval distortion in the central region (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The mechanism responsible for the massive rapidly expanding Galactic feature known as the 3-kpc arm (Rougoor and Oort, 1960) is investigated theoretically in the framework of a density-wave model of the Galaxy. The arm is attributed to outgoing waves excited at the outer Lindblad resonance (OLR) of a small rotating oval distortion near the Galactic center. Linear and nonlinear models are developed, and it is shown that a density crest at 3.5 kpc with expansion velocity 53 km/s can be generated by a distortion turning at 118 km/s kpc with a 10-percent perturbation of the main gravitational field at the OLR (located at 3 kpc). The wave character of the nonlinear solution is found to be the same as that of the linear solution and to give good agreement with the observations in terms of expansion velocity, size, shape, and mass; only the observed asymmetry of the arm is not reproduced.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 281; 600-613
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  • 37
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    Superclustering and the large-scale structure of the Universe (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A complete redshift survey of nearby rich galactic clusters is analyzed in terms of a spatial correlation function, the growth of supercluster, the presence of superclusters around the Bootes void and the discovery of a 300 Mpc void. Abell's (1958) statistical sampling of rich clusters is used for the study. Attention is given to the dependence of the correlation function on the richness of the system, with finding that chances are greater of finding rich neighbors closer together than poor neighbors. Samples of redshifts of 4 or less correlate well with clusters of redshift 5 or more. The size of intergalactic voids is proportional to the surrounding galactic excesses. Finally, the superclusters exist on scales of about 100 Mpc/h, which is larger than expected.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 3; 10-12
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  • 38
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    Reduction of flow-measurement uncertainties in laser velocimeters with nonorthogonal channels (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 5, p. 642, Accession no. A83-16486
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AIAA Journal (ISSN 0001-1452); 22; 1115-112
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  • 39
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    Ultraviolet spectral morphology of the O stars - The remarkable luminosity dependence of the Si IV stellar wind effect (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An extensive survey of ultraviolet O type spectra, by means of high-resolution data from the International Ultraviolet Explorer archives, shows a strong correlation between both the photospheric and stellar wind features, and the optical spectral types. In particular, the stellar wind effect in the Si IV resonance doublet displays a strong luminosity dependence which has not been completely described before: there is no effect anywhere on the main sequence, but it develops gradually through the intermediate luminosity classes into a full P Cygni profile in the supergiants. This behavior is in sharp contrast to that of the C IV and N V, which have strong P Cygni profiles throughout most of the O type domain, including the main sequence. The Si IV effect simultaneously provides a sensitive classification criterion and poses an outstanding problem for detailed astrophysical interpretation. In addition, a new emission feature at 1574 A, possibly due to N III or to N IV forbidden line, is reported.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 280; L27-L30
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  • 40
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    Do bipolar magnetic regions exist on the surfaces of early-type stars? (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The observations of relatively narrow absorption components of the UV resonance lines in the spectra of early-type stars are reviewed, and some new observational data are presented for Rho Leo (B1 Ib). It is shown that the discrete components which are seen in the UV resonance lines of early-type stars are a result of ejection from local spots above the photospheres of hot stars. It is suggested that localized ejection is caused by magnetic flux lines associated with a bipolar magnetic region on the surface of the star.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 280; 712-728
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  • 41
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    Models of the hard X-ray spectrum of AM Herculis and implications for the accretion rate (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Phenomenological fits to the hard X-ray spectrum of AM Hercules have failed to explain the high equivalent width (0.8 + or - 0.1 keV) of Fe K-alpha emission. The scattering and fluorescent line production in a cold or partially ionized accretion column of hard X-rays emitted at the base are investigated using the Monte Carlo method. It is shown that the Fe emission equivalent width observed in the spectrum of AM Her can be explained without resorting to an overabundance of Fe in the accreting material. For sufficient optical depth across the accretion column, equivalent widths of K-alpha emission even larger than the observed values can be obtained. The accretion rate and gravitational power can be deduced from the optical depth across the column, if the column size is known, and, together with the observed hard X-ray and polarized light luminosities, imply a lower limit for the luminosity in the UV to soft X-ray range, for which the observations give model-dependent values.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 280; 734-743
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  • 42
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    Disappearance and disintegration of comets (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The present investigation has the objective to provide a summary of the existing evidence on the disappearance of comets and to draw conclusions regarding the physical processes involved in the disappearance. Information concerning the classification of evidence and the causes of apparent disappearance of comets is presented in a table. Attention is given to the dissipating comets, the headless sungrazing comet 1887 I, and the physical behavior of the dissipating comets and the related phenomena. It is found that all comets confined to the planetary region of the solar system decay on astronomically short time scales. However, only some of them appear to perish catastrophically. Some of the observed phenomena could be successfully interpreted. But little insight has been obtained into the character of the processes which the dissipating comets experience.
    Keywords: ASTROPHYSICS
    Type: Icarus (ISSN 0019-1035); 58; 81-100
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  • 43
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    X-ray spectral signatures of accreting black holes (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The X-ray properties of the binary black hole candidates include distinctive bimodal spectral behavior where the X-ray spectra switch between being very soft (alpha greater than 3) and hard (alpha about 0.7). It is pointed out that this spectral transition occurs at about 1 percent L(edd) (for accretion onto a 10 solar masses black hole), and that this corresponds to the luminosity where an optically thick electron-positron pair plasma will form. Active galactic nuclei (AGN) are often considered to be accreting black holes. An X-ray spectral similarity between the above binary sources and both the Seyfert I and BL Lac classes of AGN is demonstrated. As many of these objects radiate most of their luminosity as X-rays, such a similarity may be expected if the underlying mechanisms are similar.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 133; 2, Ap
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    Spectral analysis of magnetohydrodynamic fluctuations near interplanetary shocks (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Preliminary results of an investigation of magnetic fluctuations seen upstream of two interplanetary shocks are presented. The spectral analysis includes calculation of the normalized reduced magnetic helicity spectrum, the normalized reduced cross-helicity spectrum, and the Alfven ratio as discussed by Matthaeus and Goldstein (1982). Minimum variance methods are used to compute wave polarization as a function of frequency. The Taylor 'frozen in flow' hypothesis is assumed to convert frequencies to wave vectors. Some of the basic properties of the waves, including the probable mode of propagation in association with both quasi-parallel forward and reverse shocks, are described. A comparison with previous results on the generation of waves at interplanetary and planetary shocks is presented.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 3762-377
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  • 45
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    Requirements for a passive IR advanced moisture and temperature sounder (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The design of a high spectral resolution, lambda/delta lambda being approximately 1200 IR, sounder capable of increasing the vertical resolution of atmospheric temperature profiles and achieving a rms accuracy of approximately 1.5 K is discussed. This sounder permits improved determination of meteorological parameters on cloudiness, surface temperature, and air-surface interactions. A set of channels from the high J lines in the R branch of the 4.3-micron CO2 band complemented by a larger set of window, humidity, and temperature channels in the 3.7-, 6.3-, 9-, and 15-micron regions is used. Design and simulation studies show that such a sounder is within the present state of the art.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 23; 979-989
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  • 46
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    Solar disk sextant (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: This paper presents the conceptual design of an instrument, called the solar disk sextant, to be used in space to measure the shape and the size of the sun and their variations. The instrumental parameters required to produce sufficient sensitivity to address the problems of solar oblateness, solar pulsations, and global size changes of climatic importance are given.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 23; 1235-123
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    HEAO 3 observations of the Crab pulsar (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Crab pulsar (PSR 0531+21) is the only pulsar which has been observed throughout almost the entire electromagnetic spectrum from 0.5 keV to over 2000 GeV. In general, the emission from the Crab nebula and its pulsar has been remarkably constant in time (except for the pulsations). However, several recent observations, especially of gamma-ray line emission, indicate possible time variations. The present investigation is concerned with the data obtained with the HEAO C-1 experiment. The data have been studied with the hope of finding information regarding a number of questions, taking into account the existence of line emission from the pulsar, the variation of the shape of the light curve with time, and the spectral variations as a function of pulsar phase. The spectrum of the total phase-averaged pulsed emission is found to be consistent with a single power-law spectrum from 50 keV to 10 MeV.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 278; 784-790
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    X-ray observations of X Persei (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The HEAO 2 Einstein Observatory was used to confirm the identification of 4U 0352 + 30 with X Per. The HEAO 2 data were analyzed in order to determine an additional point in the pulse period history of the X-ray source and to search for short binary periods. In addition, a majority of the historical X-ray observations was reanalyzed and more refined values for the pulse period as a function of time were obtained. The period history possess significant scatter, but no evidence for a measurable long-term spin-up trend is found, and hence a lower limit to the spin-up time scale is set. This lower limit is consistent with the presence of a neutron star, but it does not rule out a degenerate dwarf. The period history was also searched for evidence of binary motion, and upper limits to a(x) sin i were obtained.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 278; 711-715
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  • 49
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    Variable ultraviolet emission in SY Muscae (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The results of continued IUE monitoring of the symbiotic variable SY Muscae, following an earlier report of a radical enhancement in UV emission from the star, are reported. Over the course of one year, the prominent emission lines of N V, O V, C IV, and He II appear to be gradually decreasing in absolute intensity. This appears to coincide with a steady decline in electron density in the emission line forming region. The data are consistent with a sudden ejection event in which material expelled from the surface of a hot subdwarf has exposed the underlying UV continuum of the star. A number of strong emission lines that are photoexcited by the intense radiation field of the secondary also exhibit broad pedestal emission that suggests turbulent velocities of about 150-300 km/s in an expanding shell or possibly in an accretion disk.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 207; 575-583
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  • 50
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    A laser interferometer for measuring skin friction in three-dimensional flows (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Previously cited in issue 05, p. 643, Accession no. A83-16685
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AIAA Journal (ISSN 0001-1452); 22; 557-559
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    The remarkable ultraviolet spectrum of the planetary nebula Abell 30 (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Abell 30 has been identified as a planetary nebula in which the nucleus has experienced a final helium shell flash after ejection of the original, outer envelope. Around the central star of the nebula, four knots of material are observed. In view of the importance of the chemical composition of the ejected material for studies of advanced stages of stellar evolution, clarification of the physical conditions in the knots is vital. Data obtained of Abell 30 with the aid of the International Ultraviolet Explorer (IUE) satellite are discussed along with aspects of extinction, the He II flux, ionic abundances, the C II lambda 4267 line, questions regarding the existence of a carbon-rich core in the knot, the heating of the nebular gas, the central star, and heating by suprathermal particles from the stellar wind. The UV spectrum of the inner nebulosity of Abell 30 indicates that an extraordinary amount of energy is being deposited in the gas.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 277; 716-724
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    Simple high-temperature thermal diffusivity apparatus (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A simple and inexpensive thermal diffusivity apparatus is described for measurement up to 1600 K. The novel features of apparatus include a light pipe, a long furnace, and a differential thermocouple. A low heat-load sample holder for clamping the sample in a vertical position is also described. The results of measurements on AXM-5Q graphite are reported.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments (ISSN 0034-6748); 55; 235-237
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    A study of extreme carbon stars. I - Silicon carbide emission features (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: 10-micron spectra of many extreme carbon stars reveal a prominent emission feature near 11 microns. This is compared with laboratory spectra of SiC grains. Two distinct types of features are found, perhaps indicative of different mechanisms of grain formation in different stars. Estimates are made of probable column densities and total masses of SiC in the circumstellar shells.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 206; 137-147
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    MHD processes in the outer heliosphere (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The magnetic field measurements from Voyager and the magnetohydrodynamic (MHD) processes in the outer heliosphere are reviewed. A bibliography of the experimental and theoretical work concerning magnetic fields and plasmas observed in the outer heliosphere is given. Emphasis in this review is on basic concepts and dynamical processes involving the magnetic field. The theory that serves to explain and unify the interplanetary magnetic field and plasma observations is magnetohydrodynamics. Basic physical processes and observations that relate directly to solutions of the MHD equations are emphasized, but obtaining solutions of this complex system of equations involves various assumptions and approximations. The spatial and temporal complexity of the outer heliosphere and some approaches for dealing with this complexity are discussed.
    Keywords: ASTROPHYSICS
    Type: Space Science Reviews (ISSN 0038-6308); 39; 255-316
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    Cosmogony as an extrapolation of magnetospheric research (1984)
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    Publication Date: 2011-08-19
    Description: A theory of the origin and evolution of the Solar System which considered electromagnetic forces and plasma effects is revised in light of information supplied by space research. In situ measurements in the magnetospheres and solar wind can be extrapolated outwards in space, to interstellar clouds, and backwards in time, to the formation of the solar system. The first extrapolation leads to a revision of cloud properties essential for the early phases in the formation of stars and solar nebulae. The latter extrapolation facilitates analysis of the cosmogonic processes by extrapolation of magnetospheric phenomena. Pioneer-Voyager observations of the Saturnian rings indicate that essential parts of their structure are fossils from cosmogonic times. By using detailed information from these space missions, it is possible to reconstruct events 4 to 5 billion years ago with an accuracy of a few percent.
    Keywords: ASTROPHYSICS
    Type: Space Science Reviews (ISSN 0038-6308); 39; 65-90
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    The Harp probe - An in situ Bragg scattering sensor (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A wave sensor, consisting of parallel, evenly spaced capacitance wires, whose output is the sum of the water surface deflections at the wires, has been built and tested in a wave tank. The probe output simulates Bragg scattering of electromagnetic waves from a water surface with waves; it can be used to simulate electromagnetic probing of the sea surface by radar. The study establishes that the wave probe, called the 'Harp' for short, will simulate Bragg scattering and that it can also be used to study nonlinear wave processes.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Atmospheric and Oceanic Technology (ISSN 0739-0572); 1; 358-371
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    Radiosonde pressure sensor performance - Evaluation using tracking radars (1984)
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    Publication Date: 2011-08-19
    Description: The standard balloon-borne radiosonde employed for synoptic meteorology provides vertical profiles of temperature, pressure, and humidity as a function of elapsed time. These parameters are used in the hypsometric equation to calculate the geopotential altitude at each sampling point during the balloon's flight. It is important that the vertical location information be accurate. The present investigation was conducted with the objective to evaluate the altitude determination accuracy of the standard radiosonde throughout the entire balloon profile. The tests included two other commercially available pressure sensors to see if they could provide improved accuracy in the stratosphere. The pressure-measuring performance of standard baroswitches, premium baroswitches, and hypsometers in balloon-borne sondes was correlated with tracking radars. It was found that the standard and premium baroswitches perform well up to about 25 km altitude, while hypsometers provide more reliable data above 25 km.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Atmospheric and Oceanic Technology (ISSN 0739-0572); 1; 321-327
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  • 58
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    Abundances in galactic H II regions. III - G25.4-0.2, G45.5+0.06, M8, S159, and DR 22 (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Measurements of the ARII (6.99 microns), ArIII (8.99 microns), NeI (12.81 microns), SIII (18.71 microns), and SIV (10.51 microns) lines are presented for five compact HII regions along with continuum spectroscopy. From these data and radio data, lower limits to the elemental abundances of Ar, S, and Ne were deduced. The complex G25.4-0.2 is only 5.5 kpc from the galactic center, and is considerably overabundant in all these elements. Complex G45.5+0.06 is at seven kpc from the galactic center, and appears to be approximately consistent with solar abundance. The complex S159 in the Perseus Arm, at 12 kpc from the galactic center, has solar abundance, while M8 in the solar neighborhood may be somewhat overabundant in Ar and Ne. Complex DR 22, at 10 kpc from the galactic center in the Cygnus Arm, is overabundant in Ar. A summary of results from a series of papers on abundances is given.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 285; 174-180
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    A SAR correlation algorithm which accommodates large-range migration (1984)
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    Publication Date: 2011-08-19
    Description: This paper presents an algorithm for azimuth correlation of synthetic aperture radar (SAR) data with extraordinarily large-range migration which cannot be accommodated by the existing frequency domain interpolation approach used in current Seasat SAR processing. A mathematical model is provided for the SAR range-correlated point-target response both in the spatial and frequency domains. A simple and efficient processing algorithm derived from the exact two-dimensional correlation algorithm is given. This algorithm enables azimuth correlation by two cascaded one-dimensional correlation steps. The first step is to transform the range-correlated SAR data into the frequency domain in azimuth, followed by a newly developed range convolution filter to correct the range-dispersed spectrum of the range-correlated point-target response (RCPTR). The second step is the frequency-domain range migration correction approach for the azimuth compression. Simulation results provided here indicate that this processing algorithm yields a satisfactory compressed impulse response for SAR data with large-range migration whereas previous methods were subject to a broadening of the impulse response along range.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-22; 592-597
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    Intense X-ray flares from active stellar systems - EV Lacertae and HD 8357 (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The HEAO A-1 Sky Survey Experiment included X-ray data used to define light curves for the flare star EV Lac and for X-ray flares observed in the binary system HD 8357. The data were taken during flare events and were detailed enough to calculate the flare rates and flaring luminosities. The peak luminosities during flares were several times the luminosities in normal X-ray flares emitted by the objects. Peak luminosities reached 30-50 times the normal variations and were associated with an order of magnitude increase in energy output. EV Lac was sufficiently active to be recommended for inclusion in future X-ray monitoring programs.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 284; 270-277
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    Regularized Monte-Carlo calculations of the optical polarization induced by scattering in X-ray binaries (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The results of regularized Monte Carlo calculations of the optical polarization Stokes parameters expected as a result of scattering from gas streams or accretion wakes in close binary systems whose properties resemble those of X-ray binaries are presented. The physical processes occurring in the system are represented by a model which follows a selected sample of individual photon paths from each emitting element on the surface of the primary to the photon's detection at earth. The result represents the variations in the intensity from each individual emitting element caused by the effects of limb darkening, gravity darkening, and variation in the projected area of the emitting element as seen from the scattering element.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 138; 1, Se
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    Precession model for the nucleus of periodic Comet Kopff (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The existing data base on certain characteristics of the periodic Comet Kopff, a candidate for a NASA rendezvous mission in the 1990s, is summarized. The comet was discovered in 1906. The data are used to calculate limits to the nuclear mass (0.7-1.5 x 10 to the 16th g), equatorial radius (1.26-1.64 km), and a geometric albedo of 0.08. An equatorial rotation velocity of 8.1-10.7 hr is projected. The estimates are highly dependent on the present photometric data, which in turn depend on the insolation rate, which if different than assumed could mean that all parameters would be revised upward significantly.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 89; 1573-158
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    The H flux peak and the hydrogen abundance in N type carbon stars (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: For galactic N and late R type irregularly variable carbon stars, a comparison is made of airborne infrared spectrophotometry to spectral flux distributions derived from model atmospheres. Although the agreement is good in several respects, the H(-) emission peak at 1.6 microns, so prominent in the models, is significantly weakened in the stellar spectrophotometry. It seems unlikely that molecular bands in the stars can completely obliterate this peak. A plausible explanation is that hydrogen is deficient in these stars, most probably from an episode of mass loss. The resultant cold shells surrounding these stars should be amenable to observation by IRAS, or other far-infrared observatories.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 284; L39-L42
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    An X-ray survey of variable radio bright quasars (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A sample consisting primarily of radio bright quasars was observed in X-rays with the Einstein Observatory for times ranging from 1500 to 5000 seconds. Detected sources had luminosities ranging from 0.2 to 41.0 x 10 to the 45th power ergs/sec in the 0.5 to 4.5 keV band. Three of the fourteen objects which were reobserved showed flux increases greater than a factor of two on a time scale greater than six months. No variability was detected during the individual observations. The optical and X-ray luminosities are correlated, which suggests a common origin. However, the relationship (L sub x is approximately L sub op to the (.89 + or - .15) found for historic radio variables may be significantly different than that reported for other radio bright sources. Some of the observed X-ray fluxes were substantially below the predicted self-Compton flux, assuming incoherent synchrotron emission and using VLBI results to constrain the size of the emission region, which suggests relativistic expansion in these sources. Normal CIV emission in two of the sources with an overpredicted Compton component suggests that although they, like BL Lac objects, have highly relativistic material apparently moving at small angle to the line of sight, they have a smaller fraction of the continuum component in the beam.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 284; 491-496
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    Some properties of the filamentary nebula at 1723 - 46 (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: High resolution spectra of the interstellar NaI D2 absorption line have been obtained for seven B-type stars aligned with an extensive filamentary nebula. Very fine filaments have now been found on a high contrast print of a deep H-alpha and forbidden N II plate, making identification as a fossilized remnant probable but uncertain. The inferred age is about 20,000 yr, the distance less than 200 pc, the diameter less than 17.5 pec, but the initial energy is only about 2 x 10 to the 47th erg.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 210; 693-699
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    Laser-induced fluorescence of green plants. I - A technique for the remote detection of plant stress and species differentiation (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The laser-induced fluorescence (LIF) of green plants was evaluated as a means of remotely detecting plant stress and determining plant type. Corn and soybeans were used as representatives of monocots and dicots, respectively, in these studies. The fluorescence spectra of several plant pigments was excited with a nitrogen laser emitting at 337 nm. Intact leaves from corn and soybeans also fluoresced using the nitrogen laser. The two plant species exhibited fluorescence spectra which had three maxima in common at 440, 690, and 740 nm. However, the relative intensities of these maxima were distinctly different for the two species. Soybeans had an additional slight maxima at 525 nm. Potassium deficiency in corn caused an increase in fluorescence at 690 and 740 nm. Simulated water stress in soybeans resulted in increased fluorescence at 440, 525, 690, and 740 nm. The inhibition of photosynthesis in soybeans by 3-(3-4-dichlorophenyl)-1-1-dimethyl urea (DCMU) gave incresed fluorescence primarily at 690 and 740 nm. Chlorosis as occurring in senescent soybean leaves caused a decrease in fluorescence at 690 and 740 nm. These studies indicate that LIF measurements of plants offer the potential for remotely detecting certain types of stress condition and also for differentiating plant species.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 23; 134-142
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    Grain destruction in interstellar shocks (1984)
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    Publication Date: 2011-08-18
    Description: The destruction of interstellar grains by nonthermal sputtering, thermal sputtering, and grain-grain collisions is discussed. It is concluded that large grains are easily destroyed by shocks in the interstellar medium, but that small grains are much more persistent. Since the MRN model has many more small grains than large ones, this means that the total number of grains is not significantly reduced even when half or more of the grain material is returned to the gas phase. Thus, the small grains are always available as condensation cores for mantle formation or redepletion of refractory grain materials.
    Keywords: ASTROPHYSICS
    Type: Royal Observatory Lab. and Observational Infrared Spectra of Interstellar Dust; p 26-32
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    A balloon-borne microwave limb sounder for stratospheric measurements (1984)
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    Publication Date: 2011-08-19
    Description: The balloon-borne microwave limb sounder (BMLS) measures atmospheric thermal emission from millimeter wavelength spectral lines to determine vertical profiles of stratospheric species. The instrument flown to date operates at 205 GHz to measure ClO, O3, and H2O2. A 63 GHz radiometer will be added to test the technique for determining tangent point pressure from the MLS experiment on the upper atmosphere research satellite (UARS). Many additional species could also be measured by the BMLS. A radiometer at 270 GHz would provide measurements of HO2, NO2, HNO3, N2O, O-16O-18O-16, and HCN. With this addition, the BMLS can test the current theory of O3 photochemical balance in the upper stratosphere.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Quantitative Spectroscopy and Radiative Transfer (ISSN 0022-4073); 32; 407-433
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    Thermal modeling of Halley's Comet (1984)
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    Publication Date: 2011-08-19
    Description: The comet thermal model of Weissman and Kieffer is used to calculate gas production rates and other parameters for the 1986 perihelion passages of Halley's Comet. Gas production estimates are very close to revised pre-perihelion estimates by Newburn based on 1910 observations of Halley; the increase in observed gas production post-perihelion may be explained by a variety of factors. The energy contribution from multiply scattered sunlight and thermal emission by coma dust increases the total energy reaching the Halley nucleus at perihelion by a factor of 2.4. The high obliquity of the Halley nucleus found by Sekanina and Larson may help to explain the asymmetry in Halley's gas production rates around perihelion.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 4; 9, 19; 221-224
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    IRAS observations of cometary dust (1984)
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    Publication Date: 2011-08-19
    Description: It is pointed out that solid material present in the coma and tail of a comet is revealed by the scattering of sunlight and thermal emission of absorbed solar radiation. The large beam size and low background of the cold Infrared Astronomy Satellite (IRAS) telescope make it extremely well suited to the measurement of faint diffuse thermal emission from solid grains associated with comets. The IRAS project was conducted jointly by the Netherlands, the United Kingdom, and the U.S. Its basic objective involved a survey of the sky in four wavelength regions centered on 12, 25, 60, and 100 microns. The present paper is mainly concerned with IRAS observations of the coma-nucleus regions as defined by the maximum in the intensity distribution. Attention is given to circumstances of comet observations, dust production rates, and a discussion of the results.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 4; 9, 19
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    A comparison of the dust properties in recent periodic comets (1984)
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    Publication Date: 2011-08-19
    Description: Measurements of the thermal emission from the cometary dust coma can be used to derive the rate of dust production from the nucleus as well as the size distribution of absorbing grains. More than ten short-period comets have now been observed in the infrared over a wide range in heliocentric distance. Dust production rates are derived for these comets based on theoretical models of the thermal emission from small absorbing grains and calculations of dust grain velocities. The mean size and albedo of the dust grains is similar in these comets, with the exception of Comet Crommelin, which seems to have had larger, darker grains.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 4; 9, 19; 189-196
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  • 72
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    A new calibration of the semi-empirical photometric theory for Halley and other comets (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The semiempirical photometric theory of gas and dust production in comets (Newburn, 1979, 1981, and 1982) is recalibrated on the basis of the 17-comet compilation of spectrophotometric data of Newburn and Spinrad (1984). The results are presented in graphs and tables, and it is shown that no corrections are required for the constant R and the function delta, but that the mixing ratios (obtained as functions of heliocentric distance) can be improved, with implications for the visual-photometric comet model. Recently calculated light curves for comet Halley are compared, and the use of the nearly identical curves of Bortle and Morris (1984) and Marcus (1983) is recommended.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 4; 9, 19; 185-188
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    A cryogenic blackbody for millimeter wavelengths (1984)
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    Publication Date: 2011-08-19
    Description: The present cryogenic blackbody reference, or 'cold load', for mm-wavelength radiation has an emissivity of more than 0.99 over a two-octave wavelength range and can be used as a calibrating standard for sensitive IR photometers. The transmittance spectrum obtained indicates that wave impedance and index do not vary significantly over the 80-360 GHz range.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: International Journal of Infrared and Millimeter Waves (ISSN 0195-9271); 5; 1507-151
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    Comparative measurements using different particle size instruments (1984)
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    Publication Date: 2011-08-19
    Description: This paper discusses the measurement and comparison of particle size and velocity measurements in sprays. The general nature of sprays and the development of standard, consistent research sprays are described. The instruments considered in this paper are: pulsed laser photography, holography, television, and cinematography; laser anemometry and interferometry using visibility, peak amplitude, and intensity ratioing; and laser diffraction. Calibration is by graticule, reticle, powders with known size distributions in liquid cells, monosize sprays, and, eventually, standard sprays. Statistical analyses including spatial and temporal long-time averaging as well as high-frequency response time histories with conditional sampling are examined. Previous attempts at comparing instruments, the making of simultaneous or consecutive measurements with similar types and different types of imaging, interferometric, and diffraction instruments are reviewed. A program of calibration and experiments for comparing and assessing different instruments is presented.
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    On Bowen enhancement of the N III spectrum under solar and nebular conditions (1984)
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    Publication Date: 2011-08-19
    Description: Expected enhancement of the N III emission-line spectrum by the Bowen He II to O III to N III resonant photoexcitation process is computed using a six-configuration model. Preliminary comparisons with available solar and nebular observations indicate that the process may play only a small role, although photoexcitation quenching of the N III and O III far-infrared fine-structure lines is noted as a possibly important mechanism. Some features are discussed in connection with the nebular emission at 1750 A, which is suggested as an indicator of excitation class for planetary nebulae.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 945-951
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    The 41.5 day binary X-ray pulsar 4U 1223 - 62 (GX 301 - 2) (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Ariel 5 and SAS 3 X-ray pulse timing data for the 700 s X-ray pulsar 4U 1223 - 62 (GX 301 - 2) are reexamined in order to deduce the orbital elements of this system. The Ariel 5/SAS 3 arrival times are first reanalyzed to obtain the best solution for an orbital period close to 41.5 days and to estimate the uncertainties in it caused by unknown variations in the underlying pulse period. Spectral measurements by OSO 8 and HEAO 1 at a variety of orbital phases are presented and the origin of an unabsorbed, unpulsed soft component is discussed. OSO 8 observations of occasions when the amplitude and shape of the pulse profile changed dramatically are discussed. The global X-ray properties of the system are explained in terms of a simple stellar wind accretion model, and the interaction of the inflowing material with the neutron star magnetosphere is considered.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 856-867
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    Similar photospheres, different mantles - A study of four O stars (1984)
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    Publication Date: 2011-08-19
    Description: The present investigation is concerned with a comparison of the spectra of four O stars (10 Lac, S Mon, HD 46223, and Zeta Pup) which have similar effective temperatures, taking into account an attempt to find the reason for differences regarding the spectral type of the stars. The photospheres of the stars are examined, taking into account the effective temperatures, radii, speed of rotation, and masses. Information is presented about the equivalent widths and profiles of strong lines in the visible and ultraviolet spectra of each star. It is found that the four stars have similar photospheres but different mantles. The stars are assigned different spectral types because the empirically selected lines used for determining spectral type in class O are sensitive primarily to conditions in the mantle of the star and not to conditions in the photosphere. Questions concerning the reasons for the differences regarding the mantles are also explored.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 874-891
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    Absorption features in the 5-8 micron spectra of protostars (1984)
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    Publication Date: 2011-08-19
    Description: High signal-to-noise ratio spectra in the range of 5-8 microns of four sources embedded in molecular clouds are examined using low-temperature laboratory measurements of the 5-8-micron spectra of simple molecules and their mixtures. The absorption, apparent in all four sources, is characterized by highly distinct features ranging from two relatively narrow bands at 6.0 and 6.8 microns in W33A to a broad, shallow, and partially structured feature extending from 5.2 to 7.8 microns in Mon R2-IRS2, BN, and NGC2264. The first feature (W33A) is explained by the OH bending mode in H2O and the CH deformation modes in saturated hydrocarbons; while the second feature (Mon R2-IRS2-type) is explained by the presence of a mixture of saturated and unsaturated hydrocarbons possibly containing strongly electronegative groups.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 697-706
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    Self-absorption of high-energy Gamma-rays in Cygnus X-3 (1984)
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    Publication Date: 2011-08-19
    Description: Absorption of high-energy gamma-rays from Cyg X-3 in its own photon field by the reaction gamma + gamma yields e(+) + e(-) is considered. It is found that gamma rays with an energy around 10 to the 12th eV are attenuated, and the observed flux has to be corrected. Gamma rays with energy greater than 10 to the 15th eV which are observed are not affected by the photon field.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 338-340
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    Monte Carlo shock-like solutions to the Boltzmann equation with collective scattering (1984)
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    Publication Date: 2011-08-19
    Description: The results of Monte Carlo simulations of steady state shocks generated by a collision operator that isotropizes the particles by means of elastic scattering in some locally defined frame of reference are presented. The simulations include both the back reaction of accelerated particles on the inflowing plasma and the free escape of high-energy particles from finite shocks. Energetic particles are found to be naturally extracted out of the background plasma by the shock process with an efficiency in good quantitative agreement with an earlier analytic approximation (Eichler, 1983 and 1984) and observations (Gosling et al., 1981) of the entire particle spectrum at a quasi-parallel interplanetary shock. The analytic approximation, which allows a self-consistent determination of the effective adiabatic index of the shocked gas, is used to calculate the overall acceleration efficiency and particle spectrum for cases where ultrarelativistic energies are obtained. It is found that shocks of the strength necessary to produce galactic cosmic rays put approximately 15 percent of the shock energy into relativistic particles.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 286; 691-701
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    The collapse of the cores of slowly rotating isothermal clouds (1984)
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    Publication Date: 2011-08-19
    Description: A generalized model which accounts for the effects of initially uniform and slow rotation is defined for the spherical collapse of a singular isothermal sphere such as protosolar and binary nebulae. An initial unstable equilibrium state is described for a sound speed of 0.35 km/sec and a rotation rate of 10 to the -14th/sec for the molecular cloud surrounding the accreting core. The total angular momentum and mass of the inner cloud is set equal to solar system values. The evolution of the collapse is traced by applying a perturbation analysis to the similarity solution for a nonrotating condition, and matched asymptotic expansions solve the hydrodynamic equations. The model is concluded a valid tool for studying star and nebular disk formation.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 286; 529-551
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    Evidence for a supersonic turbulent velocity gradient in the outer photosphere of the supergiant alpha Cygni (A2Ia) (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The balloon-borne UV Stellar Spectrometer's high resolution, near-UV spectra of the supergiant Alpha Cyg are subjected to analysis in order to determine the average microturbulent line-of-sight velocity component. A value of 15.0 + or - 0.5 km/sec is obtained, which is close to the 13.7 km/sec local sound velocity, and is consistent with the view that shock waves are the dominant structure in the outer photosphere of Deneb, so that shock wave dissipation determines the thermal structure of the photosphere.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 141; 2, De
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    Vibrational and rotational excitation of CO in comets Nonequilibrium calculations (1984)
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    Publication Date: 2011-08-19
    Description: Ultraviolet observations of atomic carbon in cometary comae show that carbon-bearing compounds must comprise a significant fraction (approximately equal to or greater than 10 percent) of the volatiles. One likely source is CO. This compound is an important constituent of at least some cometary nuclei, even though it may not be the ultimate source of atomic carbon in all comets. Feldman (1983) has suggested that the relative abundance of CO may be one of the few fundamental characteristics which distinguish one comet from another. The present investigation is, therefore, concerned with the vibrational and rotational excitation of the CO molecule in cometary comae. Two previously neglected factors are taken into account in the study. The fractional populations of CO as solutions to time-dependent differential equations are derived, and a nonisothermal and cold kinetic temperature profile for the inner coma is considered.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 285; 858-869
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    The ultraviolet variability of early-type supergiants (1984)
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    Publication Date: 2011-08-19
    Description: Four early-type supergiants - HD 79186 (B5 Ia), HD 96919 (B9 Ia), HD 105056 (ON9.7 Iae), and HD 148379 (B2 Iae) - have been observed with the low-resolution spectrographs of IUE in the large aperture on 14 days. The behavior of the ultraviolet fluxes with time is studied. The light from all four stars seems to vary. Typically the dispersion about the mean magnitude at any wavelength corresponds to + or - 0.085, + or - 0.080, + or - 0.101, and + or - 0.106 mag, respectively. These amplitudes exceed the typical uncertainty in an IUE measurement of flux by about a factor of 3; they are somewhat larger than the variations known in the visible wavelength range. There are insufficient data to investigate periodicity in the observed light changes. The effective temperatures and angular diameters of the stars have been estimated using the present ultraviolet photometry, published UBV and uvby photometry, and the model-atmosphere fluxes reported by Kurucz in 1979. The program stars have dimensions typical for their spectral types. A brief discussion is given of possible causes of the variability of hot supergiants.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 285; 668-673
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    Modification to shock fitting program (1984)
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    Publication Date: 2011-08-19
    Description: A modified form of the Lepping-Argentiero single spacecraft, shock normal determination procedure is presented. The modified method incorporates a simple predictor-corrector algorithm which allows a faster convergence rate and the use of average values of the parameters for the starting vector.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 11004-11
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  • 86
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    Large-scale interplanetary magnetic fields - Voyager 1 and 2 observations between 1 AU and 9.5 AU (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The large-scale radial and temporal variations of the interplanetary magnetic field strength B observed by Voyagers 1 and 2 are discussed. Two components of the magnetic field strength were considered: (1) an average component, B sub zero, based on solar rotation averages, and (2) a fluctuation component, delta B, expressed by 10- or 24-hour averages of B normalized by the best-fit average field for the corresponding time and distance. Observations of the sector structure, interfaces, and shocks are presented to further describe magnetic field strength.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 10659-10
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    Shot noise limited detection of OH using the technique of laser-induced fluorescence (1984)
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    Publication Date: 2011-08-19
    Description: Nearly shot-noise limited detection of OH using the technique of laser-induced fluorescence is reported. A LIDAR configuration is used to excite fluoresence in a large volume and a narrow-bandwidth interference filter provides spectral discrimination. This arrangement alleviates the effect of ozone interference and facilitates image processing at relatively close distances. The detection limit is determined mainly by the short-noise of the solar background. Ground-based measurements in Dearborn indicate a detection limit of better than 1 x 10 to the 6th power OH/cubic cm over a forty-minute acquisition period. Under favorable conditions, a comparable detection limit was also observed for airborne measurements.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 23; 4076-408
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    Cyclotron emission near stellar mass black holes (1984)
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    Publication Date: 2011-08-19
    Description: Cyclotron emission in the inner regions of an accretion disk around a matter accreting black hole can be appreciable. In the case of the X-ray source Cyg X-1, cyclotron emission may provide the soft photons needed for 'Comptonization' to produce high energy X-rays. The inverse correlation between the fluxes of high energy and low energy X-rays during the 'high' and 'low' states of Cyg X-1, may be understood as a result of the variation of the rate of accretion and the Compton scattering of the cyclotron photons. In the case of the X-ray source GX 339-4, the observed optical flux during the high states does not seem to be due to cyclotron emission, but probably due to reprocessing of high energy X-rays by the outer regions of the disk.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 139; 2, Oc
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  • 89
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    Submillimeter wavelength survey of the galactic plane from l = -5 deg to l = +62 deg - Structure and energetics of the inner disk (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Observational results are presented from a new large-scale survey of the first quadrant of the galactic plane at wavelengths of 150, 250, and 300 microns, with a 10 x 10 arcmin beam. The emission detected in the survey arises from compact sources, most of which are identified with known peaks of 5 GHz or CO emission, or both, and from an underlying diffuse background with a typical angular width of about 0.9 deg (FWHM) which accounts for most of the emission. A total of 80 prominent discrete sources are identified and characterized, of which about half have not previously been reported at far-infrared wavelengths. The total infrared luminosity within the solar circle is about 1 to 2 x 10 to the 10th solar luminosity, and is probably emitted by dust that resides in molecular clouds.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 285; 74-88
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  • 90
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    The variable component of the NGC 4151 IUE spectrum - Evidence for an expanding spherical emission shell (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The profile of the forbidden line of C III (1909) is the same in two pseudo-trailed, low-resolution SWP spectra of the nucleus of the Seyfert galaxy NGC 4151 obtained with the IUE in November 1980 and December 1982, respectively. In the 1980 spectrum, the C III forbidden line profile is also very nearly the same as that of the resonance line C IV (1550). In the 1982 spectrum, the continuum is 5 times higher and C IV is both much broader and much brighter. In the difference spectrum, which is interpreted to be the spectrum of a time-variable component, C IV (1550) is the only strong emission feature. The profile of this line closely resembles that of a spherical shell surrounding a less dense gas uniformly expanding from a central opaque object. From values of the profile parameters and from the observed time variability of the object, it is inferred that the shell has a radius of about 10 to the 15th cm, a mass of 0.25 solar mass, an expansion velocity of 13,000 km/s, and an electron density of 10 to the 11th per cu cm. From the line profile and the continuum, it is inferred that the opaque central source has approximate radius of 10 to the 14th cm and temperature 23,000 K.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 285; 69-73
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  • 91
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    Gamma rays from atomic and molecular gas in the large complex of clouds in Orion and Monoceros (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A comparison of COS-B gamma-ray observations of the large complex of interstellar clouds in Orion and Monoceros with the Columbia CO and Berkeley H I surveys of this region reveals a good correlation between gamma-ray emission and total gas distribution. The observed gamma-ray emission is explainable in terms of interactions of cosmic rays that are uniformly distributed in this region with the interstellar gas. The correlation is used as the basis of a calibration of the ratio between H2 column density and the integrated CO line intensity; the value of (2.6 + or - 1.2) X 10 to the 20th mol/sq cm K km s thereby obtained is consistent with the value derived from a similar analysis for the inner galaxy.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 139; 1, Oc
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  • 92
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    Response characteristics of laser diffraction particle size analyzers - Optical sample volume extent and lens effects (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The response characteristics of laser diffraction particle sizing instruments were studied theoretically and experimentally. In particular, the extent of optical sample volume and the effects of receiving lens properties were investigated in detail. The experimental work was performed with a particle size analyzer using a calibration reticle containing a two-dimensional array of opaque circular disks on a glass substrate. The calibration slide simulated the forward-scattering characteristics of a Rosin-Rammler droplet size distribution. The reticle was analyzed with collection lenses of 63 mm, 100 mm, and 300 mm focal lengths using scattering inversion software that determined best-fit Rosin-Rammler size distribution parameters. The data differed from the predicted response for the reticle by about 10 percent. A set of calibration factor for the detector elements was determined that corrected for the nonideal response of the instrument. The response of the instrument was also measured as a function of reticle position, and the results confirmed a theoretical optical sample volume model presented here.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering (ISSN 0091-3286); 23; 610-619
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  • 93
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    On the orbit improvement results obtained by referring old cometary observations to the SAO Star Catalog (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An algorithm is presented for the automatic reduction to the SAO Star Catalog of old micrometer cometary observations of the type comet minus star. Results of a numerical test are presented showing the distinct influence of such a reduction on orbit determination results.
    Keywords: ASTROPHYSICS
    Type: JPL Cometary Astrometry; p 203-206
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  • 94
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    Scale lengths in quasi-parallel shocks (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A review was carried out of ISEE and Voyager spacecraft magnetometer data to determine if quasi-parallel bow shocks are really broad, disordered regions. The key parameter was the deceleration scale (thickness, Lp) across which random energy would need to increase and a localized electrostatic field (E) would be present. Lp would define the breadth of the shock and be associated with a plasma deceleration. The ISEE 1 satellite collected data on the electron density, bulk speed, magnetic intensity, and electron temperature in November 1977 during five traverses of the bow shock. Similar data were gathered from an interplanetary shock wave in 1981. The evidence supported the concept of a plasma deceleration across a thin layer (Lp) in both types of shocks. The layers were about 50 times (interplanetary) and 20 times (earth) thinner than surrounding magnetic fluctuation regions. It is asserted that the regions of deceleration, although much thinner, are the actual shocks and not the entire regions of magnetic fluctuations.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 7545-755
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  • 95
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    Identification of the SiCC radical toward IC +10216 - The first molecular ring in an astronomical source (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: In the radio spectrum of the envelope of the evolved carbon star IRC +10216, the fraction of lines from exotic molecules seldom or never observed in the terrestrial laboratory is exceptionally high. At least 20 lines have not been identified, and it is not known whether one, two, or a number of new molecules are involved. It is shown in the present investigation that nine of the previously unidentified lines in IRC +10216 are produced by SiCC, a radical long known to exist in stellar atmospheres. The true ground-state geometry of this radical has only been obtained recently on the basis of an elegant two-photon ionization experiment in a supersonic molecular beam. Information regarding the molecular geometry and lower rotational levels of SiCC is presented in a graph. The intensities of the SiCC lines confirm the assignments, yield new data on the temperature and density in the envelope of IRC +10216, and indicate that the amount of SiCC there is substantial.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 283; L45-L48
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  • 96
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    Far-infrared and submillimeter survey of the galactic plane from l = 11.5 deg to l = 17.5 deg (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Medium resolution (11 min) maps of the galactic plane are presented from l = 11.5 deg to l = 17.5 deg at wavelengths of 93 microns, 154 microns, and 190 microns. The maps are interpreted in terms of the temperature and spatial structure of diffuse far-infrared/submillimeter sources associated with evolved H II regions and a continuous ridge of galactic emission. The emission regions are found to be more extended at the longer wavelengths which implies that there must be a range of dust temperatures in the sources. The properties of the galactic ridge are similar to those of the sources.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 283; 566-572
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  • 97
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    Mass extinctions and missing matter (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The possible influence of 'invisible matter' on the solar system's comet halo, and therefore on quasi-periodic cometary bombardment of the earth and consequent mass extinctions, is briefly addressed. Invisible matter consisting of small or cold interstellar molecular clouds could significantly modulate the comet background flux, while invisible matter consisting of a large population of old, dead stars with a relatively small galactic concentration probably could not. It is also shown that the downward force exerted by the Galaxy will perturb the halo, but will not produce any periodicity.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 311; 17
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  • 98
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    The remarkable infrared galaxy Arp 220 = IC 4553 (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: IRAS observations of the peculiar galaxy Arp 220 = IC 4553 show that it is extremely luminous in the far-infrared, with a total luminosity of 2 x 10 to the 12th solar luminosities. The infrared-to-blue luminosity ratio of this galaxy is about 80, which is the largest value of the ratio for galaxies in the UGC catalog, and places it in the range of the 'unidentified' infrared sources recently reported by Houck et al. in the IRAS all-sky survey. Other observations of Arp 220, combined with the luminosity in the infrared, allow either a Seyfert-like or starburst origin for this luminosity.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 283; L1-L4
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  • 99
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    183 GHz water line variation - An energetic outburst in Orion KL (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Observations of the 3(13)-2(20) transition of water vapor in the direction of Ori MC1 in 1980 February show a 50 percent flux increase and an apparent additional red shift of approximately 2 km/s relative to the line observed in 1977 December. From a detailed examination of the amplitude and frequency calibration, it appears unlikely that the effect is due to systematic error. The increase is attributed to the appearance of a new component at a velocity of 12 km/s with respect to the local standard of rest. The new component also has broad wings. Increased emission from a region in the high-velocity core of Ori MC1 can be due either to additional far-IR radiation to pump the 1983 GHz transition or to a change in the physical conditions in the gas. Statistical equilibrium calculations using the large-velocity-gradient formalism were carried out to develop a model for the emission. The calculations support a model in which the gas in the region of enhanced emission is hotter than the dust. The temporal coincidence between the 183 GHz increase and the 22 GH1 water maser outburst suggests a common, impulsive cause, which has heated the gas in a part of the HV source, enhancing the emission in both transitions.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 283; 106-116
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  • 100
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    Remarks on a vibronic origin for the diffuse band spectrum (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: It has been demonstrated that the diffuse band spectrum could not originate as a series of vibronic transitions from atomic impurities in interstellar MgO grains as has recently been proposed since laboratory spectra of such materials show no evidence for such complex structure. Furthermore, recent observational evidence indicates that the extinction feature at 160 nm in the standard interstellar extinction curve upon which the identification of interstellar MgO was founded is actually the result of a calibration error in the original observational data.
    Keywords: ASTROPHYSICS
    Type: Astrophysics and Space Science (ISSN 0004-640X); 103; 2, Au
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