R. Stevenson¹, J. M. Bauer^1,2, E. A. Kramer³, T. Grav⁴, A. K. Mainzer¹ and J. R. Masiero¹

¹Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, MS 183-427, Pasadena, CA 91109, USA
²Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA
³Department of Physics, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, USA
⁴Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719-2395, USA

Comet 17P/Holmes underwent a massive outburst in 2007 October, brightening by a factor of almost a million in under 48 hr. We used infrared images taken by the Wide-Field Infrared Survey Explorer mission to characterize the comet as it appeared at a heliocentric distance of 5.1 AU almost 3 yr after the outburst. The comet appeared to be active with a coma and dust trail along the orbital plane. We constrained the diameter, albedo, and beaming parameter of the nucleus to 4.135 ± 0.610 km, 0.03 ± 0.01, and 1.03 ± 0.21, respectively. The properties of the nucleus are consistent with those of other Jupiter family comets. The best-fit temperature of the coma was 134 ± 11 K, slightly higher than the blackbody temperature at that heliocentric distance. Using Finson–Probstein modeling, we found that the morphology of the trail was consistent with ejection during the 2007 outburst and was made up of dust grains between 250 μm and a few cm in radius. The trail mass was ~1.2–5.3 × 10¹⁰ kg.

Reference
Stevenson R, Bauer JM, Kramer EA, Grav T, Mainzer AK and Masiero JR (2014) Lingering Grains of Truth around Comet 17P/Holmes. The Astrophysical Journal 787:116.
[doi:10.1088/0004-637X/787/2/116]

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