Stars like the sun may end up alone but they are born in stellar nurseries, with a thousand — or a hundred thousand — siblings. Over time, the family disbands, victims of gravitational nudges and other tidings after 4.5 billion years of life in the cosmos.
Astronomers have been on the hunt for solar siblings as part of a quest to learn more about how and where the sun was born and perhaps why our star became host to a life-bearing planet. This week, astronomers believe they have found the sun’s ‘long-lost brother’ – a stellar body born from the same gas cloud as our own star. The researchers claim there is even a ‘small’ chance that this solar sibling could host planets that harbour life. But even if its solar system proves barren, the discovery could help scientists find other stellar twins that may help shed light on how our sun formed.
The star, known as HD 162826, is about 15 percent bigger than the sun and located about 110 light-years away in the constellation Hercules.
Solar sibling HD 162826 is not visible to the naked eye, but can be seen with low-power binoculars near the bright star Vega.
Scientists matched the star’s chemistry — telltale concentrations of the rare elements barium and yttrium proved particularly useful — with the sun’s chemical components. They also tracked HD 162826’s past orbits around the center of the Milky Way to discover its link with the sun.
Out of 30 potential sibling stars, “only the star HD 162826 satisfies both our dynamical and chemical criteria for being a true sibling of the sun,”.
‘We want to know where we were born,’ Professor Ivan Ramirez from the University of Texas at Austin said.
‘If we can figure out in what part of the galaxy the sun formed, we can constrain conditions on the early solar system. That could help us understand why we are here.’
In their earliest days, collisions could have knocked chunks off of planets, and these fragments could have travelled between solar systems. These may have been responsible for bringing primitive life to Earth. Or, fragments from Earth could have transported life to planets orbiting solar siblings.
Once many more solar siblings have been identified, astronomers will be one step closer to knowing where and how the sun formed. To reach that goal, the dynamics specialists will make models that run the orbits of all known solar siblings backward in time to find where they intersect: their birthplace.