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A long-proposed tool for hunting planets has netted its first catch - a Jupiter-like planet orbiting one of the smallest stars known. The technique, astrometry, was first attempted 50 years ago to search for exoplanets: It involves measuring the precise motions of a star on the sky as an unseen planet tugs the star back and forth. But the method requires very precise measurements over long periods of time, and until now, has failed to turn up any real exoplanets (false alarms aside). Two JPL astronomers have, for the past 12 years, been mounting an astrometry instrument to a telescope at the Palomar Observatory.
After careful, intermittent observations of 30 stars, the team has identified a new exoplanet around one of them: the first ever to be discovered around a star using astrometry.
The finding confirms that astrometry could be a powerful planet-hunting technique for both ground- and space-based telescopes. For example, a similar technique would be used by SIM Lite, a NASA concept for a space-based mission that is currently being explored. The newfound exoplanet, 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 VB 10 is tiny: an M-dwarf 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 actually 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. The planet is considered an exciting discovery because it shows that planets can be found around extremely light-weight stars: a hint that nature likes to form planets, even around stars very different from the sun.
You can find Daniel Fischers Cosmic Mirror here. |
