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  • 1
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    Diffraction limited infrared images of the binary star T Tauri (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: High-resolution images of T Tau and its infrared companion have been reconstructed from near- and midinfrared data collected at the Hale 5-m telescope. The near-infrared (1-5 microns) results were obtained by 2D speckle imaging and the midinfrared (10-20 microns) results were derived from shift-and-add procedures applied to slit scans. The spectral energy distributions of the separated components were constructed from 1- to 20-micron data collected in less than half a year (September 1990 to January 1991). The spectral energy distribution of the optical component (T Tau N) is interpreted as containing two distinct constituents, a photosphere and a surrounding disk of circumstellar material. Measurements at a number of infrared wavelengths over the period December 1985 to January 1991 show a 2-mag color-independent change in the brightness of the infrared component (T Tau S). It is proposed that this may have been caused by an increase in accretion onto T Tau S and model the spectral energy distribution of T Tau S as being dominated by an accretion disk.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 102; 2066-207
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  • 2
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    SPACE: the SPectroscopic, All-Sky Cosmic Explorer (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: We describe the scientific motivations, the mission concept and the instrumentation of SPACE, a class-M mission proposed for concept study at the first call of the ESA Cosmic-Vision 2015-2025 planning cycle. SPACE aims at producing the largest three-dimensional evolutionary map of the Universe over the past 10 billion years by taking near-IR spectra and measuring redshifts of more than half a billion galaxies at 0 〈 z 〈 2 down to AB approximately 23 over 37r sr of the sky. In addition, SPACE will also target a smaller sky field, performing a deep spectroscopic survey of millions of galaxies to AB approximately 26 and at 2 〈 z 〈 l0+. Owing to the depth, redshift range, volume coverage and quality of its spectra, SPACE will reveal with unique sensitivity most of the fundamental cosmological signatures, including the power spectrum of density fluctuations and its turnover, the baryonic acoustic oscillations imprinted when matter and radiation decoupled, the distance-luminosity relation of cosmological supernovae, the evolution of the cosmic expansion rate, the growth rate of cosmic large-scale structure, the large scale distribution of galaxies. The datasets from the SPACE mission will represent a long lasting legacy that will be data mined for many years to come.
    Keywords: Astrophysics
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  • 3
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    Moderate resolution spectroscopy for the Space Infrared Telescope Facility (SIRTF) (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A conceptual design for an IR spectrometer capable of both low resolution (lambda/Delta-lambda = 50; 2.5-200 microns) and moderate resolution (1000; 4-200 microns) has been developed. This instrument will allow the spectroscopic study in the infrared of objects ranging from within the solar system to distant galaxies. The spectroscopic capability provided by this instrument for SIRTF will give astronomical orders of magnitude greater sensitivity for the investigation of faint objects than has been previously available.
    Keywords: SPACECRAFT INSTRUMENTATION
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  • 4
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    Optical properties of grains in molecular clouds and accretion disks (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-01-25
    Description: A baseline model of the composition and abundances of grains and gases in molecular cloud cores and accretion disks around young stars is defined by employing: a wide range of astronomical data and theory; the composition of primitive bodies in the solar system; and solar elemental abundances. It is proposed that in the coldest portions of these objects the major grain species include amorphous olivine, amorphous orthopyroxene, volatile and refractory organics, water ice, troilite, and metallic iron. Using a combination of laboratory measurements of optical constants and asymptotic theory, values of the real and imaginary indices of refraction of these grain species over a wavelength range that runs from the vacuum UV to the radio domain are derived. Auxiliary information for these grain species, such as their vaporization temperatures bulk densities, and their fractional abundances by mass. The above information on grain properties in molecular cloud cores and accretion disks is used to estimate the Rosseland mean opacity of the grains in both environments and the IR and microwave opacity of grains in accretion disks.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1990; p 560
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  • 5
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    Recent progress on molecular hydrogen in Orion (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The H2 emission from the Orion Molecular Cloud is, by an order of magnitude, the brightest known example of H2 emission, offering a means by which to estimate quantities connected with the mass flow. The size, temperature, velocity, and intensity of the lines can be used to infer the mass loss rate, the rate at which momentum is yielded to the cloud through masss loss, and the energy dissipation rate as the cloud is disrupted internally. Attention is accordingly given to the most recent observational results, with respect to morphology, extinction, level populations, and excitation temperature. The estimates concerning the mass loss phenomenon derived from H2 observations yield approximately the same numbers of those inferred from CO and H2O maser observations.
    Keywords: ASTROPHYSICS
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  • 6
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    High-velocity outflow sources in molecular clouds - The case for low-mass stars (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 267; April 15
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  • 7
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    Molecular hydrogen emission from W51 (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The detection of emission from the v = 1 approaches 0 S(1) quadrupole transition of H2 toward the cluster of intense infrared and H2O maser sources in W51 (north) is reported. The apparent luminosity of this line in W51 (north) is only about 4% of the luminosity of the same line toward the Kleinmann-Low infrared cluster in Orion; however, additional line-of-sight extinction and spatial extent of the source may account for the lower apparent power in W51. Similarity in the infrared and H2O properties of these clusters is addressed. The implications of the H2 emission for mass loss in the W51 region is discussed and some proposed models of radiation-driven mass outflow from pre-main sequence stars are briefly considered.
    Keywords: SPACE RADIATION
    Type: NASA-CR-164608 , CRSR-775
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  • 8
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    Simultaneous far-infrared, near-infrared, and radio observations of OH/IR stars (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Simultaneous far-infrared, near-infrared, and radio observations have been made of five infrared stars which show OH maser emission at 1612 MHz. These stars have very thick circumstellar dust shells and are not seen optically. The data permit a direct comparison of the far-infrared and maser emission from these sources, which strongly supports the hypothesis that the maser emission is pumped by 35 micron photons. A comparison with data obtained at earlier epochs suggests that the maser emission is saturated. The infrared and radio data are used together with estimates of the source distances to determine the luminosities and mass loss rates for these objects. The luminosities lie in the range 2000-30,000 solar luminosities and are consistent with either Mira variable or M supergiant classifications for the underlying stars. The estimated mass loss rates lie between 0.000005-0.00007 solar mass/year.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
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  • 9
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    Molecular hydrogen emission in NGC 7027 (1980)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The spatial distribution of the emission in the v = 1-0 S(1) line of H2 in the planetary nebula NGC 7027 is presented. The excited H2 molecules do not fill the same volume as the ionized gas and most likely reside near the outer edge of the nebula. The spatial resolution of the data, 5 arcsec, is insufficient to define the location of the molecules precisely. An upper limit to the strength of the v = 2-1 S(1) line is given; it is low enough to preclude simple ultraviolet fluorescence as the source of excitation. A simple shock model can fit the line ratio data, however, and there is enough energy in the expanding nebula to sustain such a shock. A rough estimate of 1-4 solar masses for the mass in the molecular cloud surrounding NGC 7027 is derived.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 85; July 198
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  • 10
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    High-spectral-resolution observations of the 7.7-micron feature in HD 44179 (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Observations of the moon and HD 44179 were obtained in the wavelength range of 7.5-8.5 microns at a resolving power of approximately 800. The spectrum of the moon shows absorptions caused by telluric methane. Use of the moon as a calibrator is effective in removing these atmospheric lines. The spectrum of HD 44179 shows that the 7.7-micron emission feature does not break up into discrete, resolved emission features. Instead, it must be a broad, apparently continuous, emission feature.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 94
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