Near-infrared polarimetry and photometry of recent comets

Michael S. Kelley, Chick E Woodward, Terry J Jones, William T. Reach, Jeff Johnson

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

We present near-infrared (2.2 μm) imaging polarimetry and near-infrared photometry for recent comets. The 2.2 μm polarization as a function of phase angle is 1%-2% higher than typical comet visual narrowband red polarization. This implies a general, but weak, trend to higher polarization at wavelengths longer than 0.7 μm. As found with visual narrowband red polarimetry, comets appear to divide into a high- and a low-polarization class at 2.2 μm as well. The high-polarization class is characterized by moderate to strong mid-infrared silicate emission, while the low-polarization class is characterized by weak to absent silicate emission. In contrast to C/1995 O1 (Hale-Bopp) and some other dusty comets, no significant grain population radial gradient is seen in any of the polarization maps for the six comets in our sample with near-infrared imaging polarimetry. Our analysis of previously published Hale-Bopp data shows that the polarization at 40° phase angle varies by only about a factor of 1.6 from 0.3 to 2.2 μm and is nearly flat from 0.7 to 2.2 μm. Any model of comet dust must reproduce this weak wavelength dependence.

Original languageEnglish (US)
Pages (from-to)2398-2405
Number of pages8
JournalAstronomical Journal
Volume127
Issue number4 1780
DOIs
StatePublished - Apr 1 2004

Keywords

  • Comets: general
  • Comets: individual: (10P/Tempel, 19P/Borrelly, C/1995 O1 (Hale-Bopp))
  • Infrared: solar system

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