New 3D atlas of all binary stars within 3,000 light years of Sun

Using data from Europe’s Gaia satellite, astronomers have now compiled a 3D map of every binary star within 3,000 light years of the the Sun — 1.3 million — including many widely spaced binaries that were previously not identified.

The one-of-a-kind atlas, created by Kareem El-Badry, an astrophysics Ph.D. student from the University of California, Berkeley, should be a boon for those who study binary stars — which make up at least half of all sunlike stars — and white dwarfs, exoplanets and stellar evolution, in general. Before Gaia, the last compilation of nearby binary stars, assembled using data from the now-defunct Hipparcos satellite, included about 200 likely pairs. “This is just a massive increase in sample size,” said El-Badry. “And it is an increase in what kinds of evolutionary phases we find the binaries in. In our sample, we have 17,000 white dwarfs alone. This is a much bigger census.”

The data has also shown that the bulk of these binaries are made up of twins, stars similar in mass, something that is surprising and as yet unexplained, especially for binaries where the stars are widely separated.

Scientists discover exoplanets orbiting both stars of binary system

Worlds without end: Scientists have discovered a stellar binary system which has giant exoplanets orbiting each of the system’s stars.

The twin stars studied by the group are called HD 133131A and HD 133131B. The former hosts two moderately eccentric planets, one of which is, at a minimum, about 1 and a half times Jupiter’s mass and the other of which is, at a minimum, just over half Jupiter’s mass. The latter hosts one moderately eccentric planet with a mass at least 2.5 times Jupiter’s.

The two stars themselves are separated by only 360 astronomical units (AU). One AU is the distance between the Earth and the Sun. This is extremely close for twin stars with detected planets orbiting the individual stars. The next-closest binary system that hosts planets is comprised of two stars that are about 1,000 AU apart.