Spectacular Post-Perihelion Tails of Bright Kreutz Sungrazers

Abstract

A vast majority of bright comets between the late 2nd century and the early 18th century, moving in potentially Kreutz orbits according to Hasegawa & Nakano (2001), was first sighted between 2 and 16 days after perihelion, thanks to the spectacular tails that they were then displaying. In this paper I examine the basic properties of the post-perihelion tails of the three brightest Kreutz sungrazers of the 19th and 20th centuries -- the Great March Comet of 1843 (C/1843 D1), the Great September Comet of 1882 (C/1882 R1), and Ikeya-Seki (C/1965 S1). As the pre-perihelion tail of a sungrazer sublimates completely at perihelion, the development of its post-perihelion tail starts from scratch. In the early days after perihelion, the tail length grows rapidly on account of the plasma component. At some point the dust takes over, reaching a peak length weeks later. As the geocentric distance continues to increase and the surface brightness to decline, the tail's shortening sets in. The dust tails of Ikeya-Seki and the 1843 sungrazer contained grains subjected to solar radiation pressure accelerations not exceeding 0.6-0.7 the solar gravitational acceleration, the dust tail of the 1882 sungrazer was more complex. For weeks this comet appeared like a comet in a comet, a result of disintegration of a distant companion near perihelion. Evening Kreutz sungrazers are found to have longer tails than morning ones because of geometry. Other issues are discussed and extensive sets of tail data are provided.