Track Down the Sun’s Newfound Sister

This artwork shows a star like our sun with an orbiting planet in the foreground. Illustration courtesy Gabriel Perez Diaz, Instituto de Astrofisica  de Canarias (MultiMedia Service)

Alone no more, a long-lost sibling to the sun appears to have been found 110 light-years from us. Astronomers think it will allow them to trace our stellar ancestry.

Dubbed HD 162826, the familiar-looking yellow star is thought to have been born in the same ancient gas cloud  as the sun. The same gas cloud most likely gave birth to many other stars.

“The idea is that the sun was born in a cluster with a thousand or a hundred thousand stars. This cluster, which formed more than 4.5 billion years ago, has since broken up,” said lead author of a new study, Iván Ramírez, astronomer at the University of Texas at Austin.

“A lot of things can happen in that amount of time.”

Ramírez and his team analyzed the past and future paths of 23 possible solar sibling candidates found by researchers over the years. They also looked at the chemical fingerprints of each star to help identify their pedigree. By using these two different techniques, the scientists were able to narrow it down to one confirmed sibling—HD 16826. (See “Mystery Deepens Over Where Sun Was Born.”)

But if the sun was indeed part of a much larger stellar family, where are they all now?

While a few like HD 16826 hung around our local galactic neighborhood, astronomers believe that most may have drifted away into other, much more distant parts of the Milky Way galaxy.

If more solar siblings could be tracked down, hopes are that by studying them we could unlock some of the mysteries surrounding not just how and where our solar system was born, but also why it is so hospitable to life.

“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,” explained Ramírez.

He believes that there is a small  chance that early on, the sun and its siblings may have cross contaminated each other’s planetary systems with life.

“So it could be argued that solar siblings are key candidates in the search for extraterrestrial life,” said Ramírez.

But for now, future space telescope surveys such as Europe’s Gaia mission would be required to find many more of the sun’s family to investigate the hypothesis.

The work will be published June 1 in The Astrophysical Journal.

See For Yourself

Until those future space telescopes start peering at the cosmos, seeing the sun’s sibling for yourself will have to suffice.

Located in the northern springtime constellation Hercules, HD 162826, also known as HR 6669, is not a really a naked-eye star at magnitude 6.6, but is easily seen through binoculars from anywhere in the Northern Hemisphere.

This skychart shows the general location of the sun's new sibling (HR 6669) located in the Hercules constellation now rising in the east late nights in May. Credit: SkySafari

This sky chart shows the general location of the sun’s new sibling (HR 6669) located in the Hercules constellation now rising in the east late nights in May. Image courtesy of SkySafari
This finder chart shows the specific location of the sun's new sibling (HR 6669) between the two faint naked-eye stars in Hercules constellation. Credit: SkySafari
This finder chart shows the specific location of the sun’s new sibling (HR 6669) between the two faint naked-eye stars in Hercules constellation. Image courtesy of SkySafari

To find the star, first turn to the constellation, Hercules. The star sits along an imaginary line connecting the elbow and hand of the mythical figure of Hercules, embodied in the constellation. Specifically, it sits about a third of the way up along the line between the very faint stars, Theta Herculis and Iota Herculis. (See National Geographic’s star pictures.)

Luckily Vega—one of the brightest stars in the entire sky—is also nearby, providing a convenient guidepost for tracking down the sun’s newfound sibling. The sun-like star is perched about 10 degrees above right to Vega. That separation is equal to about the width of a fist held at an arm’s length.

As Hercules himself might say, happy hunting! A search will reward you with the opportunity to gaze upon a star that looks exactly like our own sun, as seen from the depths of space.

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Changing Planet

Meet the Author
Andrew Fazekas, aka The Night Sky Guy, is a science writer, broadcaster, and lecturer who loves to share his passion for the wonders of the universe through all media. He is a regular contributor to National Geographic News and is the national cosmic correspondent for Canada’s Weather Network TV channel, space columnist for CBC Radio network, and a consultant for the Canadian Space Agency. As a member of the Royal Astronomical Society of Canada, Andrew has been observing the heavens from Montreal for over a quarter century and has never met a clear night sky he didn’t like.