Lalande 21185 - Claims of A Planetary System

Claims of A Planetary System

In 1951 Peter van de Kamp and his student, Sarah Lippincott, claimed the astrometric detection of a planetary system using photographic plates taken with the 24-in refractor telescope at Swarthmore College's Sproul Observatory. In 1960, Sarah Lippincott repeated the 1951 claim of a planetary system, only this time having different parameters. She used the original photographic plates and new plates taken with the same telescope. Photographic plates from this observatory, taken at the same time, were used by Van de Kamp for his erroneous claim of a planetary system for Barnard's Star. The photographic plates made with the Sproul 24-in refractor, and used for these and other studies, were later shown to be flawed. The claims of planetary companions for both stars were refuted in 1974 with astrometric measurements made by George Gatewood of the Allegheny Observatory.

In 1996 the same George Gatewood prominently announced at an AAS meeting and to the popular press the discovery of multiple planets in this system, detected by astrometry. The initial report of a planet was based on a very delicate analysis of the star's position over the years which suggested reflex orbital motion due to one or more companions. Gatewood claimed that such companions would usually appear more than 0.8 arc second from the M dwarf itself. However a paper by Gatewood published only a few years earlier and subsequent searches by others, using coronagraphs and multifilter techniques to reduce the scattered-light problems from the star, have yet to positively identify any such companions and so his claim remains unconfirmed and is now in doubt.