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Vega

StarDate: 
June 1, 2016

When it comes to understanding a star, it’s all a matter of perspective. The angle at which you view the star makes a big difference in what you know about it.

Consider Vega, one of the brightest stars in the northern sky. It’s low in the northeast at nightfall, and climbs high overhead later on.

For a long time, astronomers thought the star was about three times as massive as the Sun, and perhaps no more than a hundred million years old. So when they discovered a cloud of dust grains around Vega, they thought it might be the raw material for planets.

But a decade ago, they found that they were seeing Vega from a completely different angle than thought. It turns out that we’re looking almost directly down on one of the star’s poles. That perspective makes it more difficult to measure Vega’s details.

Once they knew the correct angle, astronomers determined that the star rotates so fast that it’s almost ripping itself apart. They also found that it’s a bit smaller than thought, but a good bit older.

Yet even today, there’s uncertainty about its age. A study a few years ago placed the age at about 455 million years. But another study just a few years later gave the age as 700 million years. Either way, that means the dust around Vega can’t be the material for a newly forming planetary system. Instead, it’s probably debris from collisions between asteroids or other bodies that have already taken shape — perhaps including fully grown planets.

Script by Damond Benningfield

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