Nemesis (hypothetical star)

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While looking up the name for a new operation, I found this whole study on hypothetical stars that are kinda interesting. 

Nemesis is a hypothetical red dwarf or brown dwarf, originally postulated in 1984 to be orbiting the Sun at a distance of about 95,000 AU (1.5 light-years), somewhat beyond the Oort cloud, to explain a perceived cycle of mass extinctions in the geological record, which seem to occur more often at intervals of 26 million years. As of 2012, more than 1800 brown dwarfs have been identified. There are actually fewer brown dwarfs in our cosmic neighborhood than previously thought. Rather than one star for every brown dwarf, there may be as many as six stars for every brown dwarf. The majority of solar-type stars are single. The previous idea stated half or perhaps most stellar systems were binary, trinary, or multiple-star systems associated with clusters of stars, rather than the single-star systems that tend to be seen most often. In a 2017 paper, Sarah Sadavoy and Steven Stahler argued that the Sun was likely part of a binary system at the time of its formation, leading them to suggest "there probably was a Nemesis, a long time ago". Such a star would have separated from this binary system over four billion years ago, meaning it could not be responsible for the more recent perceived cycle of mass extinctions, Douglas Vakoch told Business Insider, adding that "If the sun really was part of a binary star system in its early days, its early twin deserves a benign name like Companion, rather than the threatening Nemesis."