Photometry of the Kreutz Comets 1996-2005 (original) (raw)

2008

Abstract

We present the results of our photometric study of the Kreutz group of sungrazing comets observed by SOHO-LASCO from 1996-2005. We extend the work of Biesecker et al. (2002), expanding the sample from 141 to more than 900 comets. The Kreutz comets seen by SOHO are produced by fragmentation from the more massive members of the family which include Ikeya-Seki (C/1965 S1 = 1965f) and C/1882 R1. None of the SOHO observed Kreutz comets have survived perihelion due to both their small size (we infer sizes less than 50 meters in radius) and perihelion distances below 2 solar radii. Kreutz comets typically brighten at a rate near r-7.3 when first entering the SOHO field of view (at distances near 30 solar radii), then rapidly transition to brightening at a rate near r-3.8 from 16-24 solar radii. We find that they do not have a bimodal distance of peak brightness as previously reported by Biesecker et al. (2002), but instead peak between 10-14 solar radii, suggesting there is a continuum, perhaps due to compositional variations, rather than two distinct subpopulations. Inside of 10 solar radii but prior to perihelion, the comets fade rapidly and disappear by 6 solar radii. We derive nuclear sizes of up to 50 meters in radius, with a cumulative size distribution of N(>R) R-2.2 for comets larger than 5 meters in radius. This size distribution cannot explain the six largest members of the family seen from the ground, suggesting that either the family is not collisionally evolved or that the distribution is not uniform around the orbit. The total mass of the distribution up to the largest expected size ( 500 meters) is 4x1014 g, much less than the estimated mass of the largest ground observed members. This research was supported by NASA Planetary Atmospheres grants NAG513295 and NNG06GF29G.

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