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  • SOLAR PHYSICS  (42)
  • SPACECRAFT INSTRUMENTATION  (3)
  • 1
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    The soft x ray telescope for Solar-A (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The Solar-A satellite being prepared by the Institute for Sapce and Astronautical Sciences (ISAS) in Japan is dedicated to high energy observations of solar flares. The Soft X Ray Telescope (SXT) is being prepared to provide filtered images in the 2 to 60 A interval. The flight model is now undergoing tests in the 1000 foot tunnel at MSFC. Launch will be in September 1991. Earlier resolution and efficiency tests on the grazing incidence mirror have established its performance in soft x rays. The one-piece, two mirror grazing incidence telescope is supported in a strain free mount separated from the focal plane assembly by a carbon-epoxy metering tube whose windings and filler are chosen to minimize thermal and hygroscopic effects. The CCD detector images both the x ray and the concentric visible light aspect telescope. Optical filters provide images at 4308 and 4700 A. The SXT will be capable of producing over 8000 of the smallest partial frame images per day, or fewer but larger images, up to 1024 x 1024 pixel images. Image sequence with two or more of the five x ray analysis filters, with automatic exposure compensation to optimize the charge collection by the CCD detector, will be used to provide plasma diagnostics. Calculations using a differential emission measure code were used to optimize filter selection over the range of emission measure variations and to avoid redundancy, but the filters were chosen primarily to give ratios that are monotonic in plasma temperature.
    Keywords: SOLAR PHYSICS
    Type: NASA, Goddard Space Flight Center, Max '91 Workshop 2: Developments in Observations and Theory for Solar Cycle 22; p 158-172
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  • 2
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    Results from the X-ray polychromator on SMM (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Observations of the soft X-ray emitting plasma by means of the X-Ray Polychromator (XRP) on the Solar Maximum Mission satellite are described. The scientific advances achieved by use of the XRP are in the areas of: (1) flare morphology, (2) spectroscopy and plasma diagnostics, (3) chromospheric evaporation and the physics of flare loops, (4) studies of the microwave emission mechanisms of active regions, (5) the fluorescent excitation of Fe II K-alpha radiation, (6) measurement of variations of calcium abundance for X-ray plasmas, and (7) soft X-ray observations of spray transients. The findings in each of these areas are discussed.
    Keywords: SOLAR PHYSICS
    Type: Societa Astronomica Italiana, Memorie (ISSN 0037-8720); 55; 4 19; 673-684
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  • 3
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    Fluorescent excitation of photospheric Fe K-alpha emission during solar flares (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The Bent Crystal Spectrometer on the NASA Solar Maximum Mission satellite provides high spectral and temporal resolution observations of the Fe K-alpha lines. Analyses have been conducted of spectra from almost 50 solar flares that occurred during 1980. These data strongly support fluorescent excitation of photospheric iron by photons of E greater than 7.11 keV emitted by the hot coronal plasma produced during the flare. After comparison of the data with a model, the observed K-alpha line widths are discussed along with estimates of the size of the emitting region, the height of the coronal source and the photospheric iron abundance.
    Keywords: SOLAR PHYSICS
    Type: (ISSN 0273-1177)
    Format: text
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  • 4
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    Direct evidence for chromospheric evaporation in a well-observed compact flare (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Observations of the solar flare of May 7, 1980 using several Solar Maximum Mission instruments are presented as an investigation of the phenomenon of chromospheric evaporation. The total amount of plasma at temperatures greater than 2 x 10 to the 6th K were determined from the X-ray data, and the amount of plasma that was evaporated from the chromosphere was determined from the H-alpha data. The H-alpha profiles indicate that for the flare as a whole, at the time of peak soft X-ray emission measure, the number of atoms evaporated from the chromosphere was 7 x 10 to the 37th. The soft X-ray emission measure of 1 x 10 to the 49th/cu cm, coupled with the flare volume estimate of 10 to the 26th cu cm, indicates that there were 3 x 10 to the 37th electrons in the soft X-ray plasma with temperatures greater than 2 x 10 to the 6th K. These results indicate that enough material had been evaporated from the chromosphere to account for the X-ray plasma. Taken together, the H-alpha, soft X-ray, and hard X-ray images indicate that chromospheric evaporation is driven both by flare-accelerated electrons during the impulsive phase and by conduction during the thermal phase.
    Keywords: SOLAR PHYSICS
    Type: (ISSN 0273-1177)
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  • 5
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    Observations of the limb solar flare on 1980 April 30 with the SMM X-ray polychromator (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 244
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  • 6
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    X-ray spectra of solar flares obtained with a high-resolution bent crystal spectrometer (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Preliminary results obtained for three solar flares with the bent crystal spectrometer on the SMM are presented. Resonance and satellite lines of Ca XIX and XVIII and Fe XXV and XXIV are observed together with the Fe XXVI Lyman-alpha line. Plasma properties are deduced from line ratios and evidence is presented for changes of line widths coincident with the occurrence of a hard X-ray impulsive burst. Fe K-alpha spectra from a disk center and a limb flare agree with the predictions of a fluorescence excitation model. However, a transient Fe K-alpha burst observed in a third flare may be explained by the collisional ionization of cool iron by energetic electrons.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 244
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  • 7
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    X-ray line widths and coronal heating (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Preliminary results of spectroscopy and imaging of a solar active region and flare plasma in soft X-ray emission lines are presented. Observed X-ray line widths in a nonflaring active region are broader than the Doppler width corresponding to the local electron temperature. An analysis of 41 soft X-ray flares within a single active region reveals a preference for flares to occur at locations that already show enhanced X-ray emission and to favor magnetic complexity over high gradient. However, flares do not appear to be directly responsible for the heating and X-ray production of the active regions.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 244
    Format: text
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  • 8
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    Solar Maximum Mission experiment - Early results from the soft X-ray polychromator experiment (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: It is pointed out that the X-ray polychromator experiment has been in operation on the Solar Maximum Mission satellite for more than three months. Using a number of different modes, the polychromator is observing flares and active regions in the wavelength range 1-23 A. These modes include polychromatic imaging, high resolution line profiles, high dispersion spectra, and light curves with high time-resolution. Data are described and some of the early analysis and interpretation is presented. All the interpretations are based on simple approximate methods; it is noted, however, that in most cases more elaborate and reliable methods are close to being applied.
    Keywords: SOLAR PHYSICS
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  • 9
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    Analysis of X-ray and EUV spectra of solar active regions (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Data acquired by two flights of an array of six Bragg crystal spectrometers on an Aerobee rocket to obtain high spatial and spectral resolution observations of various coronal features at soft X-ray wavelengths (9-23A) were analyzed. The various aspects of the analysis of the X-ray data are described. These observations were coordinated with observations from the experiments on the Apollo Telescope Mount and the various data sets were related to one another. The Appendices contain the published results, abstracts of papers, computer code descriptions and preprints of papers, all produced as a result of this research project.
    Keywords: SOLAR PHYSICS
    Type: NASA-CR-161364
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  • 10
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    Large-aperture high-resolution X-ray collimator for the Solar Maximum Mission (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A description is presented of a flight-qualified large-aperture 12 x 12-arcsec angular resolution multigrid X-ray collimator developed for the Solar Maximum Mission (SMM) flat crystal spectrometer. This collimator, designed for the 1.4-22.4-A wavelength range, utilizes an optical bench/metering structure to align and support prealigned grid subassemblies. The optical bench is a lightweight, rigid, and stable aluminum honeycomb structure. The grids are of a compound and bimetallic design, having 63.5-micron square holes on an 88.9-micron spacing in 8-micron thick gold, which is in turn supported by a 76-micron thick Invar grid having 600-micron square holes on a 739-micron spacing. The small apertures in the gold provide the 12-arcsec collimation with the Invar grids providing wide angle off-axis blocking out to an approximately 35 arcmin view angle. The collimator has seven individual channels, four of a 5.1- x 10-cm area and three of a 1.3- x 10-cm area. Laboratory measurements gave an average angular resolution of 12.5 arcsec FWHM with 0.259 transmission for the large-area channels and 12.0 arcsec and 0.200 transmission for the small-area channels. A thermal filter composed of two layers of approximately 1000-A thick aluminum prevents solar heating of the front collimator grids by absorbing longer wavelength radiation while passing most of the X radiation in the band of interest.
    Keywords: SPACECRAFT INSTRUMENTATION
    Type: Applied Optics; 19; Sept. 1
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