Astronomers see exoplanet orbiting its parent star!

By PHIL PLAIT - BAD ASTRONOMY BLOG
Added: Fri, 11 Jun 2010 02:43:04 UTC

This is extremely cool news: astronomers have, for the first time, directly seen an exoplanet orbiting its star from one side to the other!

This makes me happy scientifically, of course, but also for personal reasons. Let me tell you a story. Two, in fact…

1) [Story the First] Beta Pic: the star, the planet, the disk

The star in question is Beta Pictoris (or just Beta Pic to its friends), a very young star — it’s only a few million years old, compared to the Sun’s advanced age of 4.56 billion — with about twice the Sun’s mass and 9 times its brightness. As stars go, Beta Pix is pretty close, just 63 light years away, and is easily bright enough to be seen with the unaided eye from the southern hemisphere.

In the above picture, taken using one of the European Southern Observatory’s ginormous 8.2 meter units of the Very Large Telescope, Beta Pic is represented by the dot in the center. The star is so bright its light swamps everything around it, so the star itself has been blocked by a piece of metal inside the camera that took the shot (that’s the reason for the dark circle in the center of the picture). This allows us to see much fainter stuff near the star.

This picture is actually a composite of three separate observations. The outer part with the blue fuzzy stuff was observed in 1996, and I’ll get back to that in a sec. The good stuff is in the center: two images of the planet, called Beta Pic b, are superposed in the picture; it was observed in 2003 (left blob), then again in late 2009 (right blob). Observations taken just months before in 2008 and 2009 observation didn’t show the blob at all — it must have been too close to the star to be seen clearly — indicating this really is a planet orbiting the star, and not just some background object like a star or galaxy. In other words, astronomers have captured the motion of the planet as it physically moved from one side of the star to the other!
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TAGGED: SPACE, TECHNOLOGY