Are periodic mass extinctions driven by a distant solar companion?
“. Nature 308 (5961): 713715 Davis, M.; Hut, P., Muller, R.A. (1984). “Extinction of species by periodic comet showers”. Nature 308 (5961): 715717] This hypothesis proposes that the sun may have an as yet undetected companion star in a highly elliptical orbit that periodically disturbs comets in the Oort cloud, causing a large increase in the number of comets visiting the inner solar system with a consequential increase in impact events on Earth. This became known as the Nemesis (or, more colorfully, Death Star) hypothesis. If it does exist, the exact nature of Nemesis is uncertain. Richard A. Muller suggests that the most likely object is a red dwarf with magnitude between 7 and 12, while Daniel P. Whitmire and Albert A. Jackson argue for a brown dwarf. See this site:– http://muller.lbl.gov/pages/lbl-nem.htm Muller.lbl.gov If a red dwarf, it would undoubtedly already exist in star catalogs, but its true nature would only be detectable by measuring its parallax; due to orbiting the Su
