Steven Stahler, a UC Berkeley research astronomer, and Sarah Sadavoy, a NASA Hubble fellow at the Smithsonian Astrophysical Observatory, have posted findings on Arxiv which indicate that all sun-like stars were probably born as binary pairs. The research has been accepted for publication in Monthly Notices of the Royal Astronomical Society. The findings indicate that the Sun was born with a twin, which has wandered off somewhere in the neighborhood, within the Milky Way.
Many stars are part of multiple star systems, including our nearest stellar neighbour, Alpha Centauri, which is a triple star system. Astronomers have sought an explanation for multiple star systems for a long time. The researchers looked for clues in stellar nurseries and observed the Perseus cloud, a region with a lot of young stars. The survey showed that all of the widely separated binary systems in the cloud were made up of very young stars. A widely separated binary is a pair of stars more than 500 astronomical units (AU) apart, a single AU is the average distance between the Sun and the Earth.
Stars form inside dense cores, which are oval shaped. Mathematical models indicate that the dense cores collapse into at least two stars because of the oval shapes. The study indicates that nearly all stars are born in a litter. Stahler explains, "As the egg contracts, the densest part of the egg will be toward the middle, and that forms two concentrations of density along the middle axis. These centers of higher density at some point collapse in on themselves because of their self-gravity to form Class 0 stars."
According to the research, solitary low mass sun-like stars are not the way they were created, but are the result of binary stars that have broken up. Although astronomers have long suspected that stars were born in litters, there have been no direct observations so far to support the hypothesis. The new data and mathematical models are just the start and more research needs to be done to understand the exact process of star birth.