Call it stars reunited. It should now be possible to find the lost siblings of our own Sun.
Most relatively massive stars are born in broods, or clusters, rather than alone. And the Sun appears to be no different 鈥� meteorites show evidence of a supernova that exploded near the infant Sun, and the orbits of icy bodies in the outer solar system appear to have been shaped by a close encounter with one of the Sun鈥檚 siblings.
Advertisement
But over the last few billion years, these stars have gone their separate ways, blending in among the galaxy鈥檚 myriad background stars.
of the University of Amsterdam in the Netherlands suggests a way to find them. He estimated the size and mass of the cluster of stars that spawned our Sun 4.6 billion years ago.
By taking into account various factors, such as the fact that close stellar encounters did not prevent the formation of our solar system, he calculated that the cluster measured 5 to 20 light years across, and weighed in at between 500 and 3000 solar masses.
Chemical relations
Using that information, he calculated the likely escape velocities of the Sun鈥檚 siblings as they drifted apart. He found that a few percent of the siblings should still be in our cosmic vicinity, in the constellations Cygnus and Vela, both within 300 light years (see this illustration). 鈥淚t鈥檚 pretty straightforward,鈥� he says. 鈥淔or some reason, no one thought about doing this analysis before.鈥�
Searching existing catalogues for stars with the same orbital characteristics through the galaxy and the same chemical makeup as the Sun might uncover lost relatives, Portegies Zwart says. Europe鈥檚 upcoming mission , slated for launch in late 2011, might be able to track them down, as it will map the position and motion of a billion nearby stars.
However, of the Harvard-Smithsonian Center for Astrophysics thinks Portegies Zwart may be too optimistic. Passing molecular clouds may have thrown the siblings out much faster and farther than expected, he says.
Journal reference:
