Groombridge 1830 is also known as HR 4550, HD 103095, and Gl 451. Nearby dim yellow subdwarf star. It was first mentioned in Groombridge's catalog of circumpolar stars. It was found to have the highest proper motion of any star by Argelander in 1842 (replacing 61 Cygni), and is now known to have the third highest. It is likely a halo star, and has not evolved onto the main sequence despite its old age 5 or 10 billion years old. Being a halo star that does not follow the rotation of the galaxy explains its high proper motion. It is part of the Groombridge 1830 Moving Group, which consists of several other subdwarf stars. Van de Kamp recorded a flare which he assumed was a dim companion star. It has since been found to undergo superflares.