Authors

T. J. Jones; D. Stark; C. E. Woodward; M. S. Kelley; L. Kolokolova; D. Clemens;A. Pinnick

Comments

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Abbreviated Journal Title

Astron. J.

Keywords

comets : individual (73P); techniques : polarimetric; DEEP IMPACT; IMAGING POLARIMETRY; WAVELENGTH DEPENDENCE; COMET 2P/ENCKE; AGGREGATE PARTICLES; LIGHT-SCATTERING; HALLEYS COMA; PHASE ANGLES; HALE-BOPP; POLARIZATION; Astronomy & Astrophysics

Abstract

We report imaging polarimetry of segments B and C of the Jupiter-family comet 73P/Schwassmann-Wachmann 3 in the I and H bandpasses at solar phase angles of approximately 35 degrees and 85 degrees. The level of polarization was typical for active comets, but larger than expected for a Jupiter-family comet. The polarimetric color was slightly red (delta P/delta lambda = +1.2 +/- 0.4) at a phase angle of similar to 35 degrees and either neutral or slightly blue at a phase angle of similar to 85 degrees. Observations during the closest approach from 2006 May 11-13 achieved a resolution of 35 km at the nucleus. Both segments clearly depart from a 1/rho surface brightness for the first 50-200 km from the nucleus. Simulations of radiation-driven dust dynamics can reproduce some of the observed coma morphology, but only with a wide distribution of initial dust velocities (at least a factor of 10) for a given grain radius. Grain aggregate breakup and fragmentation are able to reproduce the observed profile perpendicular to the Sun-comet axis, but fit the observations less well along this axis (into the tail). The required fragmentation is significant, with a reduction in the mean grain aggregate size by about a factor of 10. A combination of the two processes could possibly explain the surface brightness profile of the comet.

Journal Title

Astronomical Journal

Volume

135

Issue/Number

4

Publication Date

1-1-2008

Document Type

Article

Language

English

First Page

1318

Last Page

1327

WOS Identifier

WOS:000254655300017

ISSN

0004-6256

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