Friday, February 10, 2017

ALMA observations of HD 163296 reveal the presence of two planets.

ALMA observations of HD 163296 reveal the presence of two planets.:

HD 163296 is a very young star about 400 light-years from Earth. That’s pretty close as these kinds of objects go, making it a ripe target for astronomers to observe. And by young I do mean young; it’s only about 4 million years old—the Sun is literally a thousand times older than that!—so astronomers chomp at the bit to observe it. It’s a perfect opportunity to see how stars form.

And not just stars, but planets! We’ve known for a while that HD 163296 has a dusty disk surrounding it, and that this is exactly the sort of thing we expect planets to form in. And now new observations show pretty convincing evidence that this baby star has at least two baby planets orbiting it!

The image above reveals the disk around HD 163296 as observed by ALMA, the Atacama Large  Millimeter/submillimeter Array. ALMA sees “colors” of light well outside what our eyes can, wavelengths longer even than infrared. Warm dust around a star emits this kind of light, and the image above shows just that. You can easily see the dust is not just in a disk, but in a set of rings around the star.

Using physics and math, we can predict that forming planets will carve gaps just like that in the disk, their gravity drawing in the material around them as they grow. And there those gaps are!

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