2010MNRAS.402.2744J

Comet 17P/Holmes was observed for linear polarization using the optical polarimeter mounted on the 1.2-m telescope atop Gurushikhar peak near Mt. Abu during the period 2007 November-December. Observations were conducted through the International Halley Watch narrow-band (continuum) filters. During the observing run, the phase angle was near 13° at which the comet showed negative polarization. On the basis of the observed polarization data, we find comet 17P/Holmes to be a typical comet with usual dust characteristics. We note that radial rate of change of brightness in coma in red band is higher than that in blue band; it has decreased by a factor of 3.6 and 2.5, respectively, in red and blue bands during the November-December run, indicating relative increase in the abundance of smaller dust particles outward. Radial brightness variation seen near the nucleus on November 6 is indicative of the presence of a blob or shocked region beyond 10arcsec from the nucleus which has gradually smoothened by December 13. The brightness distribution is found steeper during November 5-7 as compared to that on December 13.