How Hot Is WASP-12b?
WouterUsing the transit method, the Hubble Space Telescope observed the transiting exoplanet WASP-12b, which orbits close to its host star. The star is a 12th-magnitude F dwarf located in southeastern Auriga. Its age is estimated at about two Gyr.
The planet is about the same size as Jupiter and is a “hot Jupiter” – a gaseous planet that orbits very close to its host star. These planets are heated to very high temperatures and are sometimes called “VJs” or “very hot Jupiters”.
The orbital radius of WASP-12b is about three times that of its host star, and its radius is nearly two times the radius of Jupiter. It completes an orbit around its host star in less than a day. The planet’s orbit is circular, and its average orbital velocity is about 232 kilometers per second. The planet has a tidal lock, which means it orbits around the star in the same way it is pulled toward the star.
The planet has an average albedo of about 0.064. Its night side is about 900 degrees cooler than its day side. This is due to the planet’s atmosphere. When the planet orbits close to the star, its atmosphere is vaporized, and the gases escape into space. This causes the planet to reflect very little light.
The planet is doomed. It is likely to collide with the host star in the near future. Its orbital period is the shortest of any planet in the SuperWASP catalogue.
