Almost eight years of observations using the Hubble Space Telescope, the Fred Lawrence Whipple Observatory in Arizona, and Roque de Los Muchachos Observatory in the Canary Islands, Spain, provided sufficient evidence of a second star’s ‘wake’ in the guise of a high-density trail of gas in Betelgeuse’s bloated atmosphere.

A small companion star has been confirmed, revealed by the wake it leaves as it plows through the red giant’s atmosphere. Ignoring interference from the occasional dusty sneeze, Betelgeuse’s light seems to vary according to two distinct cycles. One lasts about 400 days and has been linked to internal pulsations. The second, however, lasts around 2,100 days, and has been much harder to account for. The leading hypothesis suggests a small, dim companion star on a tight orbit around the red giant, with observations culminating in a likely detection last July. Now, Betelgeuse’s buddy has finally been confirmed, several months after its proposed name, Siwarha, was accepted. The study ‘Betelgeuse: Detection of the Expanding Wake of the Companion Star‘ has been accepted for publication in The Astrophysical Journal.

NASA Hubble Helps Detect ‘Wake’ of Betelgeuse’s Elusive Companion Star