New star provides picture of Sun’s future


Graphic: fig1.jpg

Pictured is an artist’s rendering of CoRoT Sol 1 and a chronology of the Sun’s evolution based on data from the Subaru Telescope and the CoRoT space mission. The illustration indicates how CoRoT Sol 1’s discovery will greatly improve our understanding of how the Sun may evolve and allows astronomers to test current theories of solar evolution against an observed, evolved solar twin. (Credit: do Nascimento et al.)

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By COLIN M. STEWART

Tribune-Herald staff writer

Consider it a 6.7 billion-year-old crystal ball for astronomers.

A newly discovered star in the furthest reaches of the Milky Way may help scientists peering through the Subaru Telescope atop Mauna Kea to better understand and predict the behavior of the very important star right in Earth’s front yard — the Sun.

Dubbed CoRoT (Convection, Rotation and planetary Transits) Sol 1, the star is considered a “solar twin” of the Sun, having the same mass and chemical composition, according to a release from the Subaru Telescope. At 2.2 billion years older than the Sun, CoRoT Sol 1 provides an important look at how our sun may age.

“The mass and chemical composition of a star are the main characteristics that determine its evolution,” reads an article on the Subaru Telescope website. “Studying stars with the same mass and composition as the Sun, the so-called ‘solar twins,’ can give us more information about our own Sun; solar twins of various ages offer snapshots of the Sun’s evolution at different phases.”

Using the Subaru Telescope’s 8.2-meter mirror and its high dispersion spectrograph, which can identify up to 100 different elements on far-away bodies, a team of Japanese and Brazilian astronomers led by Jose Dias do Nascimento of the Department of Theoretical and Experimental Physics at the Universidad Federal do Rio Grande do Norte, Brazil, determined the star’s age to be 6.7 billion years. Meanwhile, information about the star’s rotation — 29 days, plus or minus five days — was provided by measurements taken by the CoRoT space telescope.

“In two billion years’ time, about the solar twin’s actual age, the Sun’s radiation may increase and make the Earth’s surface so hot that liquid water can no longer exist there in its natural state,” Nascimento said of his team’s findings.

Subaru Telescope spokeswoman Suzanne G. Frayser said Monday that the discovery shows just how much the science of astronomy has to offer.

“If you consider that we’re talking about objects that are billions of years old, and being able to find an object out there in this huge, star-studded galaxy of ours with billions and billions of stars … I find that fascinating,” she said. “It’s amazing that we have the technology and the expertise to do that.”

The discovery came after the team narrowed down a list of possible solar twin candidate stars from a sample of 150,000. That list was further narrowed down to three stars, which were analyzed in close detail by the Subaru spectrograph. Two of the stars were discarded as not matching the Sun, but CoRoT Sol 1 appeared to be a likely match, although it was more evolved.

CoRoT Sol 1 is the first solar twin to be discovered by the CoRoT satellite, and the furthest solar twin from the Sun, according to the team’s scientific paper, available at arxiv.org. Only about two dozen solar twins have so far been identified throughout the universe. In contrast to other solar twins, which are relatively bright, CoRoT Sol 1 is more than 200 times fainter than the brightest solar twin known. It is located in the constellation Unicorn (Monoceros).

Going forward, the team plans to continue its research into the Sun and how it compares with other suns in the galaxy.

“They intend to describe (the Sun’s) rotation evolution by finding solar twins representing a broad range of stellar ages and then placing the Sun within this context,” the Subaru release states.

Email Colin M. Stewart at cstewart@hawaiitribune-herald.com.

 

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