WASP-12b
Encyclopedia
WASP-12b is an extrasolar planet
orbiting the star
WASP-12
, discovered by the SuperWASP
planetary transit
survey. Its discovery was announced on April 1, 2008. Due to its extremely close orbit to its star, it has one of the lowest densities for exoplanets ('inflated' by the flux of energy from the star). The planet takes only a little over a day to orbit the star, in contrast to 365 days for the Earth
to orbit the Sun
. Its distance from the star is only 1/44 the Earth’s distance from the Sun, with the eccentricity
the same as Jupiter
's.
at a rate of about 10−7 MJ
(about 189 quadrillion
tonnes) per year. The so-called "tidal heating", and the proximity of the planet to its star, combine to bring the surface temperature to more than 2500 kelvins (2,226.9 °C).
On 20 May 2010, the Hubble Space Telescope
spotted WASP-12b being consumed by its star. Despite scientists already being aware that stars can consume planets, this is the first time such an event has been spotted 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 its Cosmic Origins Spectrograph
(COS). The Hubble Telescope observations have confirmed predictions published in Nature
in 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.
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 journal Nature
.
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...
orbiting the star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
WASP-12
WASP-12
WASP-12 is a magnitude 11 yellow dwarf star located approximately 800 light-years away in the constellation Auriga. WASP-12 has a mass and radius similar to the Sun- Planetary system :...
, discovered by the SuperWASP
SuperWASP
SuperWASP is an international academic organisation performing an ultra-wide angle search for transiting extrasolar planets with the aim of covering the entire sky down to ~15th magnitude.-Equipment:...
planetary transit
Astronomical transit
The term transit or astronomical transit has three meanings in astronomy:* A transit is the astronomical event that occurs when one celestial body appears to move across the face of another celestial body, hiding a small part of it, as seen by an observer at some particular vantage point...
survey. Its discovery was announced on April 1, 2008. Due to its extremely close orbit to its star, it has one of the lowest densities for exoplanets ('inflated' by the flux of energy from the star). The planet takes only a little over a day to orbit the star, in contrast to 365 days for the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
to orbit the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. Its distance from the star is only 1/44 the Earth’s distance from the Sun, with the eccentricity
Orbital eccentricity
The orbital eccentricity of an astronomical body is the amount by which its orbit deviates from a perfect circle, where 0 is perfectly circular, and 1.0 is a parabola, and no longer a closed orbit...
the same as Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
's.
Description
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 its atmosphereAtmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...
at a rate of about 10−7 MJ
Jupiter mass
Jupiter mass , is the unit of mass equal to the total mass of the planet Jupiter . Jupiter mass is used to describe masses of the gas giants, such as the outer planets and extrasolar planets. It is also used in describing brown dwarfs....
(about 189 quadrillion
Quadrillion
Quadrillion may mean either of the two numbers :* 1,000,000,000,000,000 – for all short scale countries; increasingly common meaning in English language usage* 1,000,000,000,000,000,000,000,000 – for all...
tonnes) per year. The so-called "tidal heating", and the proximity of the planet to its star, combine to bring the surface temperature to more than 2500 kelvins (2,226.9 °C).
On 20 May 2010, the Hubble Space Telescope
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
spotted WASP-12b being consumed by its star. Despite scientists already being aware that stars can consume planets, this is the first time such an event has been spotted 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 its Cosmic Origins Spectrograph
Cosmic Origins Spectrograph
The Cosmic Origins Spectrograph is a science instrument that was installed on the Hubble Space Telescope during Servicing Mission 4 in May 2009. It is designed for ultraviolet spectroscopy of faint point sources with a resolving power of ≈1,550–24,000...
(COS). The Hubble Telescope observations have confirmed predictions published in Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
in 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 a significantly enhanced carbon-to-oxygen ratio 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 journal Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
.
See also
- SuperWASPSuperWASPSuperWASP is an international academic organisation performing an ultra-wide angle search for transiting extrasolar planets with the aim of covering the entire sky down to ~15th magnitude.-Equipment:...
- BPM 37093BPM 37093BPM 37093 is a variable white dwarf star of the DAV, or ZZ Ceti, type, with a hydrogen atmosphere and an unusually high mass of approximately 1.1 times the Sun's. It is about 50 light-years from Earth, in the constellation Centaurus, and vibrates; these pulsations cause its luminosity to vary...
, a "diamond star" - Midnight, a fictional diamond planet from the eponymous Doctor Who episodeMidnight (Doctor Who)"Midnight" is the tenth episode of the fourth series of British science fiction television series Doctor Who. It was first broadcast on BBC One on 14 June 2008. The episode placed much more emphasis on the role of David Tennant as the Tenth Doctor than in the rest of the fourth series, with the...
External links
- SuperWASP Wide Angle Search for Planets: The Planets, SuperWASPSuperWASPSuperWASP is an international academic organisation performing an ultra-wide angle search for transiting extrasolar planets with the aim of covering the entire sky down to ~15th magnitude.-Equipment:...
. - Star-hugging planet is hottest and fastest found, New Scientist.
- BBC News - Hubble spots a planet-eating star
- WASP-12b in transit (lightcurve)