Our Sun Was Likely Born in Binary System, Losing Its Twin Star Later

A new analysis from the University of California-Berkeley, in collaboration with Smithsonian Astrophysical Observatory at Harvard University, revealed that our sun -- like other stars in the universe -- was born in a multi-star system and most likely lost its twin along the way.

The new analysis, published in the journal Monthly Notices of the Royal Astronomical Society, showed that all sun-like stars are born with companions. In the case of our sun, its companion star was dubbed Nemesis. Though never been found, the current study suggests that Nemesis is just out there, probably mixed with all the other stars in our galaxy.

"Our work is a step forward in understanding both how binaries form and also the role that binaries play in early stellar evolution," said Sarah Sadavoy, a NASA Hubble fellow at the Smithsonian Astrophysical Observatory and first author of the study, in a press release. "We now believe that most stars, which are quite similar to our own sun, form as binaries."

For their analysis, the researchers looked into the cloud of gas and young stars in the Perseus molecular cloud, which is about 600 light-years away from Earth and about 50 light-years long. All stars form in molecular clouds.

Using the Very Large Array, a collection of radio dishes in New Mexico, astronomers have completed a survey of all the young stars inside the molecular cloud. These young stars were less than about four million years old.

Based on their observations, the researchers found that nearly all the stars in the Perseus molecule cloud were gravitationally bounded. The researchers noted that protostars, or the egg-like objects in the gas cloud could require a common center of gravity with a companion star in order to accumulate mass.

The researchers observed that about 60 percent of the young stars loss their companion star as time pass by. It is possible that the companion stars drifted away from their partners, gaining distance that can severe their gravitational pull with each other. This might also be the case for our sun and Nemesis.