Tuesday, September 16, 2008

First picture of a planet around a sun-like star?

A team of University of Toronto astronomers took what might be the first picture of an extra-solar planet — a planet around a sun other than our own — orbiting a star very similar to our own.

Astronomers have photographed other extra-solar planets, but they were all orbiting brown dwarfs, which are very small, very cold stars. Because they don't radiate much light, it's easier to spot (with optical telescopes) the planets that might orbit them.

In this case, the object was photographed orbiting the star with the catchy name 1RSX J160929.1-210524. This is a very young star. So young, in fact, that the planet has not yet cooled. This means it is radiating its own energy, making it possible to see. The star is a little smaller than our sun, and the planet is about the size of Jupiter, but much hotter (about 1500ºC, compared to Jupiter's temperature of -110ºC).

The star is 500 light years away. Scientists believe it will be another two years before we know for certain that it's moving along with the star, hence the reason why it's still open to conjecture as to whether or not the smaller object is a planet and whether or not it belongs to that star.

An additional interesting point is that the planet is 330 AU out from the star. An AU is an astronomical unit, equal to the distance from the Earth to the sun. Neptune is about 30 AU from our sun, so this planet is 10 times the distance from its star as Neptune is from the sun, which isn't a situation that fits the current solar system models.

This is going to be an interesting object to pay attention to. Meanwhile, the picture is available at the Gemini Observatory web site. Just follow this link: http://www.gemini.edu/sunstarplanet.

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