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  • 1
    Electronic Resource
    Electronic Resource
    Infrared Spectroscopy of Comet Hale-Bopp (1997)
    Springer
    Earth, moon and planets 78 (1997), S. 71-80 
    Details
    ISSN: 1573-0794
    Keywords: Infrared ; spectroscopy ; composition ; comets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract High resolution (λ/δλ ∼ 20,000) spectra of comet C/1995 O1 (Hale-Bopp) in the 2–5 μm region were obtained during UT 2–5 March 1997 using CSHELL at the NASA Infrared Telescope Facility (IRTF) on Mauna Kea. The heliocentric and geocentric distances of the comet were ∼1.1 AU and ∼1.5 AU,respectively. We detected emission lines of the gas-phase molecules H2O, 4, C2H6, C2H2, HCN, and CO and derived absolute production rates and relative abundances for all species. We also used the 2-dimensional nature of the CSHELL data to investigate the spatial distribution of the molecules and find evidence that CO was derived at least partly from an extended source in the coma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006227530238
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  • 2
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    A sensitive upper limit on the methane abundance in Comet Levy (1990c) (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Results are presented on a ground-based search for fluorescent emission from CH4 at 3.3 microns in a newly discovered long-period comet, Comet Levy (1990c). It was found that the upper limit to the CH4 abundance in Comet Levy is similar to the Comet Halley CH4 abundance estimated from lower resolution IR spectra by Kawara et al. (1988). The Comet Levy CH4 abundance is significantly lower than the abundance derived by Larson et al. (1989) from a possible detection of CH4 in Comet Wilson.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 372; L113-L11
    Format: text
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  • 3
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    Vibrational and rotational excitation of CO in comets Nonequilibrium calculations (1984)
    In:  Other Sources
    Details
    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
    Format: text
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  • 4
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    Limit on the CH4/CO ratio in Comet Levy (1990c) and comparisons with other comets (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Near-infrared observations of comet Levy (1900c) were made on UT 4.3 and 5.3 Sep. 1990 from the United Kingdom Infrared Telescope on Mauna Kea. A scanning Fabry-Perot interferometer in combination with a cooled grating spectrometer was used to make a sensitive search for fluorescent emission from the v zub 3 band of CH4 near lambda approx. 3.3 microns. If CH4 is a parent molecule released directly from the nucleus, then the 3 sigma limit on its abundance is CH4/H2O approx. less than 0.0031, assuming that the kinetic temperature of the inner coma is approx. 50 K and that the CH4 spin species are equilibrated at a temperature approx. greater than 50 K. Since International Ultraviolet Explorer (IUE) observations of CO in Levy indicate that CO/H2O approx. 0.04 (Feldman et al.), researchers find that CH4/CO approx. less than 0.1. Infrared spectroscopic searches for CH4 in Comet Halley also yielded no positive detections; the more sensitive upper limit from the latter observations is CH4/H2O approx. less than 0.002. Since CO/H2O approx. 0.05 in Halley (not including the extended source of CO), the upper limits on the CH4/CO ratios are almost identical for comets Levy and Halley. A marginal infrared detection of the CH4 v sub 3 band in comet Wilson yielded CH4/H2O approx. 0.01 to 0.05 (Larson et al.), but there was no positive detection of CO. If the identification of the feature in the infrared spectrum of comet Wilson is correct, then that would indicate a very high CH4/CO ratio in this comet.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Abstracts for the International Conference on Asteroids, Comets, Meteors 1991; p 233
    Format: application/pdf
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  • 5
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    An attempt to detect mass loss from Alpha Lyrae with the VLA (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The interpretation of the infrared excess from Alpha Lyrae as seen by the Infrared Astronomy Satellite in terms of thermal emission from a circumstellar shell of large particles follows from the recognition that small dust grains would be removed from the vicinity of the star by radiation pressure and Poynting-Robertson drag. However, this explanation is viable only if there is no resupply of small grains via mass loss from Alpha Lyr itself. Radio-continuum observations were used to constrain the stellar mass loss to less than 3.4 x 10 to the -10th solar mass/yr. The observations thus support the conclusion that the infrared excess is due to residual solid matter from the prestellar nebula.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 294; 646-648
    Format: text
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  • 6
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    Observations of CO emission from a dense cloud associated with the supernova remnant IC 443 (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 54; 3, Fe; Feb. 197
    Format: text
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  • 7
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    The molecular complexes in Orion (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Line emission from CO at 2.6 mm is observed over an area of 28 square degrees in the Orion region. Most of the emission comes from two giant molecular complexes, roughly associated with Ori B and Ori A. The latter provides the best example of a giant molecular complex at the end of a sequence of OB association subgroups of decreasing age. This complex is apparently rotating with an angular velocity 4.5 by 10 to the -15th power per sec, but in a direction opposed to the Galactic rotation. The apparently denser parts of the cloud are rotating at a somewhat greater angular velocity. The total mass of the molecular gas derived from the observations is 200,000 solar masses, implying that roughly half the matter in this region is in the form of molecular hydrogen.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 215
    Format: text
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  • 8
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    Vibrationally excited silicon monoxide masers (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Published data on a select group of SiO maser sources have been analyzed for velocity variations as a function of phase. No apparent correlation was found to a level of about 2 km/s. This places constraints on the location of the maser molecules. Such a correlation should be present at some level. The implications for future high resolution infrared measurements are discussed.
    Keywords: ASTROPHYSICS
    Type: PB81-233744 , Symposium on Interstellar molecules; Aug 06, 1979 - Aug 10, 1979; Mont Tremblant, Quebec; Canada
    Format: text
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