Researchers at the University of Texas have identified a star that formed in the same star cluster as our Sun. Dubbed HD 162826, the star is 15 percent more massive than the Sun and resides 110 light-years away. It's hoped the discovery of this "sibling" will help us understand more about where and how the solar system originated, and might also point us to the best candidates for finding extraterrestrial life.
Circa 4.5 billion years ago, a large collapsing cloud of gas inside an interstellar cloud gave birth to our Sun, along with a cluster of other stars. As the collapse phase ended, a supernova "contaminated" the cloud with a cocktail of barium and yttrium, giving the cluster a unique chemical signature. The star cluster has since broken up, and those stars are now spread out across the entire length of the Milky Way, along with hundreds of billions of other stars.
Now, a team led by Ivan Ramirez at the University of Texas has combined information on trajectory and chemical signature of several candidates to identify one such star. HD 162826, a "sibling" of our Sun, is a relatively modest 110 light-years away and can be seen with low-power binoculars, near the star Vega, in the Hercules constellation.
As luck would have it, astronomers with the McDonald Observatory in West Texas have been studying the star for over 15 years. Among other things, we know that the star doesn't have any Jupiter-sized planets orbiting it, but might have smaller, Earth-sized planets in its system.
This is important because Ramirez and colleagues say that there is a heightened chance that the Sun's "siblings" are hosting life within their planetary systems. When the stars were still in a dense cluster, violent collisions could have knocked off planetary chunks and asteroids may have traveled between solar systems, perhaps bringing the building blocks of life along with them.
In about a month's time, the Gaia spacecraft will wrap up its commissioning phase and start surveying the skies, collecting the accurate distance and trajectory of one billion stars in our galaxy. This will inundate astronomers with avalanches of data, allowing them to vastly expand their search for more solar siblings. The job of sifting through this data will be made more efficient by the methods that Ramirez and colleagues used in their search. When more have been found, we will be much closer to understanding exactly when and where our Sun formed and how life started within the solar system.
The research will appear in the June issue of The Astrophysical Journal.
Source: University of Texas
