The planet that is getting eaten up (WASP-12b)

The planet that is getting eaten up (WASP-12b)

Size comparison of WASP-12b (right) with Jupiter.


The planet is so close to WASP-12 that the star's tidal forces are distorting the planet into an egg shape and pulling away itsatmosphere at a rate of about 10?7MJ(about 189quadrilliontonnes) per year.The so-called "tidal heating", and the proximity of the planet to its star, combine to bring the surface temperature to more than2,500 K(2,200C).

On May 20, 2010, theHubble Space Telescopespotted WASP-12b being "consumed" by its star. Scientists had been aware that stars could consume planets; however, this was the first time such an event had been observed so clearly. NASA has estimated that the planet has 10 million years left of its life.

The Hubble Space Telescope observed the planet by using itsCosmic Origins Spectrograph(COS). The Hubble Telescope observations have confirmed predictions published inNaturein February 2009 by Peking University's Shu-lin Li. The planet's atmosphere has ballooned to be nearly three times the radius of Jupiter, while the planet itself has 40% more mass than Jupiter.


Carbon content

Recent evidence indicates that WASP-12b has an enhanced carbon-to-oxygen ratio, significantly higher than that of the Sun, indicating that it is a carbon-rich gas giant. The C/O ratio compatible with observations is about 1, while the solar value is 0.54. The C/O ratios suggest that carbon-rich planets may have formed in the star system.One of the researchers behind that study commented that "with more carbon than oxygen, you would get rocks of pure carbon, such as diamond or graphite".

The published study states: "Although carbon-rich giant planets like WASP-12b have not been observed, theory predicts myriad compositions for carbon-dominated solid planets. Terrestrial-sized carbon planets, for instance, could be dominated by graphite or diamond interiors, as opposed to the silicate composition of Earth."These remarks have led the media to pick on the story,some even calling WASP-12b a "diamond planet".

The carbon content of the planet is located within its atmosphere, in the form of carbon monoxide and methane. The study appears in the journalNature.

This artist's concept shows the searing-hot gas planet WASP-12b (orange orb) and its star.

Candidate satellite

Russian astronomers studying a curve of change of shine of the planet observed splashes of light indicative of anextrasolar moonorbiting the planet.

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