The Sun is an unusual star in several ways. It’s the only star known to support life. It’s in the top 10 percent of the most-massive stars in the galaxy. And it’s in the minority in another way: it moves through the galaxy alone.
Like all stars, the Sun probably was born in a cluster – a group of hundreds or thousands of stars. But the Sun’s birth cluster fell apart, with the stars going their own ways.
Most stars hang on to one or more of their siblings. Most of them form binaries – two stars bound by their gravity. Others form systems of three stars or more – all the way up to seven. The heavier a star, the more likely it is to have companions. For stars like the Sun, the odds are about 50-50.
The Sun has no companions today. But it could have in the distant past. In its crowded nursery, close encounters with other stars could have pulled the Sun and any possible companions away from each other.
Astronomers haven’t found any long-lost binary “twin” of the Sun. But they have found some stars that could have been born in the same cluster. A great example is HD 162826. Astronomers at McDonald Observatory found that its composition and motion are very close matches to the Sun’s.
HD 162826 rises above Vega, the brightest star of Lyra. They’re in the northeast in late evening. But you need binoculars to see this likely sibling to the Sun.
More about binaries tomorrow.
Script by Damond Benningfield