SOFIA infrared spectrophotometry of comet C/2012 K1 (Pan-STARRS)
- Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street, SE, Minneapolis, MN 55455 (United States)
- Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States)
- Center for Astrophysics and Space Sciences, University of California, San Diego, Dept 0424, 9500 Gilman Drive, La Jolla, CA 92093-0424 (United States)
- NASA Ames Research Center, MS 245-3, Moffett Field, CA 94035-0001 (United States)
- Department of Physics, University of Cincinnati, Cincinnati, OH 45221 (United States)
- The Aerospace Corporation, Los Angeles, CA 90009 (United States)
- USRA-SOFIA Science Center, NASA Ames Research Center, Moffett Field, CA 94035 (United States)
We present pre-perihelion infrared 8–31 μm spectrophotometric and imaging observations of comet C/2012 K1 (Pan-STARRS), a dynamically new Oort Cloud comet, conducted with NASA's Stratospheric Observatory for Infrared Astronomy facility (+FORCAST) in 2014 June. As a “new” comet (first inner solar system passage), the coma grain population may be extremely pristine, unencumbered by a rime and insufficiently irradiated by the Sun to carbonize its surface organics. The comet exhibited a weak 10 μm silicate feature ≃1.18 ± 0.03 above the underlying best-fit 215.32 ± 0.95 K continuum blackbody. Thermal modeling of the observed spectral energy distribution indicates that the coma grains are fractally solid with a porosity factor D = 3 and the peak in the grain size distribution, a{sub peak} = 0.6 μm, large. The sub-micron coma grains are dominated by amorphous carbon, with a silicate-to-carbon ratio of 0.80{sub −0.20}{sup +0.25}. The silicate crystalline mass fraction is 0.20{sub −0.10}{sup +0.30}, similar to with other dynamically new comets exhibiting weak 10 μm silicate features. The bolometric dust albedo of the coma dust is 0.14 ± 0.01 at a phase angle of 34.°76, and the average dust production rate, corrected to zero phase, at the epoch of our observations was Afρ ≃ 5340 cm.
- OSTI ID:
- 22882741
- Journal Information:
- Astrophysical Journal, Vol. 809, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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