page_title: CoRoT-7b
section_title: Characteristics
hierarchical_section_title: CoRoT-7b / Characteristics
caption_attribution_description: English: The exoplanet Corot-7b is so close to its Sun-like host star that it must experience extreme conditions. This planet has a mass five times that of Earth’s and is in fact the closest known exoplanet to its host star, which also makes it the fastest — it orbits its star at a speed of more than 750 000 kilometres per hour. The probable temperature on its “day-face” is above 2000 degrees, but minus 200 degrees on its night face. Theoretical models suggest that the planet may have lava or boiling oceans on its surface.
context_page_description: CoRoT-7b is an exoplanet orbiting around the star CoRoT-7, in the constellation Monoceros, at 489 light years from Earth. It was first detected photometrically by the French-led CoRoT mission and reported in February 2009. Until the announcement of Kepler-10b in January 2011, it was the smallest exoplanet to have its diameter measured, at 1.58 times that of the Earth, and the first potential extrasolar terrestrial planet to be found. The planet has a very short orbital period, revolving around its host star in about 20 hours.
  Combination of the planet's diameter derived from transit data with the planet's mass derived from radial velocity measurements, meant that the density of CoRoT-7b was about the same as that of Earth and, therefore, that CoRoT-7b was a terrestrial planet like Earth and was not a gas giant like Jupiter. The radial velocity observations of CoRoT-7 also detected a second super-Earth, CoRoT-7c, which has a mass 8.4 times that of Earth and orbits every 3.7 days at a distance of 6.9 million km.
context_section_description: Although CoRoT-7b's mass remains uncertain, with a range between 2 and 8 Earth masses, its radius and orbital period are well known from CoRoT photometry: it orbits very close to its star (1/23rd the distance from the Sun to Mercury) with an orbital period of 20 hours, 29 minutes, and 9.7 seconds and has a radius of 1.58 Earth radii. CoRoT-7b had the shortest orbit of any planet known at the time of its discovery.
  Due to the high temperature, it may be covered in lava. The composition and density of the planet, though weakly constrained, make CoRoT-7b a probably rocky planet, like Earth. It could belong to a class of planets that are thought to contain up to 40% water (in the form of ice and/or vapor) in addition to rock.  However, the fact that it formed so close to its parent star may mean that it is depleted of volatiles. A strong possibility exists that the planet's rotation is tidally locked to the orbital period, so that temperatures and geologic conditions on the sides of the planet facing towards and away from the star may be dramatically different. Theoretical work suggests that CoRoT-7b could be a chthonian planet (the remains of a Neptune-like planet from which much of the initial mass has been removed due to close proximity to its parent star). Other researchers dispute this, and conclude CoRoT-7b was always a rocky planet and not the eroded core of a gas or ice giant, due to the young age of the star system.
  Any departure from circularity of its orbit (due to the influence of host star and neighboring planets) could generate intense volcanic activity similar to that of Io, via tidal heating.
  A detailed study of the extreme properties of CoRoT-7b has been published, concluding that, despite the mass uncertainty, the planet is Earth-like in composition. The extreme proximity to the star should prevent the formation of a significant atmosphere, with the dayside hemisphere as hot as the tungsten filament of an incandescent bulb, resulting in the formation of a lava ocean. The researchers propose to name this new class of planets, CoRoT-7b being the first of them, "lava-ocean planets".
caption: Artist’s impression of CoRoT-7b.
  Credit: ESO/L. Calçada.
exif: {"Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop 7.0", "Image DateTime": "2009:12:30 14:52:09", "Image ExifOffset": "156", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "294", "Thumbnail JPEGInterchangeFormatLength": "3165", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "3000", "EXIF ExifImageLength": "2000"}