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Astronomers Discover Sun's 'Sibling'


Solar sibling HD 162826 is not visible to the unaided eye, but can be seen with low-power binoculars near the bright star Vega in the night sky. (Ivan Ramirez)

Solar sibling HD 162826 is not visible to the unaided eye, but can be seen with low-power binoculars near the bright star Vega in the night sky. (Ivan Ramirez)

Scientists say they have found what they’re calling the “first sibling” of the Sun.

Astronomer Ivan Ramirez of the University of Texas led a team which looked at two important “genetic” traits between the two stars.

Born of the same cloud of gas and dust as the Sun some 4.6 billion years ago, HD 162826 is a relative next door neighbor, 110 light-years away in the constellation Hercules.

HD 162826 is not visible to the naked eye, but can be seen with a pair of binoculars, scientists say.

It’s about 15 percent more massive than the Sun and has a slightly hotter surface temperature, researchers said.

To determine HD 162826’s relation to the Sun, the Texas scientists looked at stars in what is called the solar neighborhood, some 300-350 light years across.

They then determined which stars were on similar orbits around the center of the Milky way.

“The idea is we wanted to know where the star has been in the past,” Ramirez told VOA. “We had to turn the clock back.”

Finding 30 candidates which had been following a similar path around the galaxy as the Sun, scientists performed a chemical analysis of 23 of them using high-resolution spectroscopy.

Using both methods, the researchers arrived at the conclusion that HD 162826 is the Sun’s sibling.

One key result of this survey, they said, was to narrow down the elements to determine a possible relation among stars; highly variable chemical elements are influenced by where in the galaxy the star formed, Ramirez said.

“You can concentrate on certain key chemical elements that are going to be very useful,” Ramirez said in a statement, adding that the “elements barium and yttrium [are] particularly useful.”

How many other siblings could the Sun have?

“Based on this one detection, there could be a few hundred more siblings,” Ramirez said. “But they’re all going to be tiny stars that we can’t see so we can’t do a detailed chemical analysis.”

So far, no exoplanets have been observed orbiting HD 162826, but that doesn’t mean they’re not there.

It just means there are no massive, Jupiter-like planets in that system, Ramirez said.

“Most likely it has exoplanets,” Ramirez said. “We see planets everywhere and there’s no reason for it not to have them.”

He said there is a “small, but not zero” chance that solar siblings could host planets that support life.

“It could be argued that solar siblings are key candidates in the search for extraterrestrial life,” Ramirez said in a statement.

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