Astrometry Finds Planet

It seems that astrometry has finally succeeded at detecting a planet. A star and its planets perform a complex dance as they move through space. In astrometry planet hunting one looks for a planet by looking for the “wobble” of a star as it moves across the sky. This is contrast with the two other methods used to detect planets around stars, which use radial velocity or transits to detect the planets. Now it seems that a team from JPL has used a series of measurements over 12 years to detect a Jupiter sized planet tugging on its star, VB 10. The wobble in this case is a movement of about one sixth of an arcsecond per year. Very cool.

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    … The newfound exoplanet, called VB 10b, is about 20 light-years away in the constellation Aquila. It is a gas giant, with a mass six times that of Jupiter’s, and an orbit far enough away from its star to be labeled a “cold Jupiter” similar to our own. In reality, the planet’s own internal heat would give it an Earth-like temperature.
    The planet’s star, called VB 10, is tiny. It is what’s known as an M-dwarf and is only one-twelfth the mass of our sun, just barely big enough to fuse atoms at its core and shine with starlight. For years, VB 10 was the smallest star known — now it has a new title: the smallest star known to host a planet. In fact, though the star is more massive than the newfound planet, the two bodies would have a similar girth….
    Because the star is so small, its planetary system would be a miniature, scaled-down version of our own. For example, VB 10b, though considered a cold Jupiter, is located about as far from its star as Mercury is from the sun. Any rocky Earth-size planets that might happen to be in the neighborhood would lie even closer in.

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