Identified: the Sun's sibling

Find could help narrow the search for extraterrestial life

Credit: Ivan Ramirez/Tim Jones/McDonald Observatory

The star can easily be seen with low-power binoculars

One of the Sun’s ‘long-lost siblings’ has been found by a team of researchers. They say the star was almost certainly born in the same cloud of gas and dust as our own over 4.5 billion years ago.

The star, HD 162826, is located 110 lightyears away and is 15 per cent more massive than the Sun. Located in the constellation of Hercules, the star can easily be seen with binoculars, not too far from Vega.

According to most current theories, the Sun began its life in a cluster with thousands of other stars. In the billions of years since, the cluster broke up and while some stars remained close to home, others were scattered far throughout the galaxy.

The team began searching for these distant relations by identifying 30 potential candidates and obtaining high-resolution spectroscopy of them, to gain a deep understanding of their chemical makeup. Next the researchers traced the stars’ orbits backwards to find out where they had been and where they were going. Combining both the chemical and dynamical information, the team found there was one candidate that most likely originated from the same place as our Sun: HD 162826.

But the identification of one star is not the end of the team’s work. With new telescopes such as Gaia imaging billions of stars, the number of potential candidates could increase 10,000 times over. The search for this one star will speed up the hunt for more members of our stellar family tree as scientists now know what to look for.

“We’ve learned not to invest a lot of time in analysing every detail in every star,” says Ivan Ramirez of the University of Texas at Austin, who led the team. “Instead we’ll concentrate on certain key chemical elements that are going to be very useful.”

After identifying more of our stellar relatives, astronomers aim to work out where and how the Sun first formed. By tracing back the orbits of every solar sibling and finding where they intersect, researchers will finally be able to find the Sun’s birthplace in the Galaxy.

It’s also hoped that such stars could be key candidates in the search for extraterrestrial life. During the early days within the stellar nursery, collisions would have knocked chunks off the infant planets in orbit around these stars. The fragments could have travelled between planetary systems, potentially carrying a few microbial hitchhikers with them and seeding life on other worlds. Ramirez says the chance of such an occurance is “small, but not zero,” and so far no planets have been spotted orbiting around HD 162826.

“We want to know where we were born,” says Ramirez. “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.” 


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