Formation and Evolution of the Stream of SOHO Kreutz Sungrazers. I. History and Preliminary Investigations

The nearly continuous stream of miniature comets dominated by the Kreutz sungrazers has been an unexpected bonanza for cometary science initiated by the launch of the Solar and Heliospheric Observatory (SOHO) in 1995. Over the nearly 30 years since the time, no serious attempt has been made to formulate a self-consistent model for the formation and evolution of this stream of Kreutz comets -- the goal of the present two-part investigation. Part I describes historical highlights of the research that has been relevant to the problem of SOHO sungrazers (including the major contributions by Hubbard, Kreutz, and Marsden) and furnishes preliminaries of diagnostic value that are intended to facilitate, and provide critical information for, the work in Part II. Formerly noted issues, such as the high frequency of close pairs in the SOHO database, are proposed to be products of a broader process of swarming, seen in both the nodal longitude and time. I present examples of tight swarms revealed by high arrival rates of the SOHO Kreutz sungrazers, primarily from Population I.