An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, initially detected in 1988, was confirmed in 2003. As of 26 August 2023, there are 5,502 confirmed exoplanets in 4,064 planetary systems, with 876 systems having more than one planet. The James Webb Space Telescope (JWST) is expected to discover more exoplanets, and also much more about exoplanets, including composition, environmental conditions and potential for life.
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk. Planets grow in this disk by the gradual accumulation of material driven by gravity, a process called accretion. The Solar System has at least eight planets: the terrestrial planets Mercury, Venus, Earth and Mars, and the giant planets Jupiter, Saturn, Uranus and Neptune. These planets each rotate around an axis tilted with respect to its orbital pole. All planets of the Solar System other than Mercury possess a considerable atmosphere, and some share such features as ice caps, seasons, volcanism, hurricanes, tectonics, and even hydrology. Apart from Venus and Mars, the Solar System planets generate magnetic fields, and all except Venus and Mercury have natural satellites. The giant planets bear planetary rings, the most prominent being those of Saturn.
CoRoT was a space telescope mission which operated from 2006 to 2013. The mission's two objectives were to search for extrasolar planets with short orbital periods, particularly those of large terrestrial size, and to perform asteroseismology by measuring solar-like oscillations in stars. The mission was led by the French Space Agency (CNES) in conjunction with the European Space Agency (ESA) and other international partners.
Hot Jupiters are a class of gas giant exoplanets that are inferred to be physically similar to Jupiter but that have very short orbital periods. The close proximity to their stars and high surface-atmosphere temperatures resulted in their informal name "hot Jupiters".
Any planet is an extremely faint light source compared to its parent star. For example, a star like the Sun is about a billion times as bright as the reflected light from any of the planets orbiting it. In addition to the intrinsic difficulty of detecting such a faint light source, the light from the parent star causes a glare that washes it out. For those reasons, very few of the exoplanets reported as of April 2014 have been observed directly, with even fewer being resolved from their host star.
CoRoT-2b is the second extrasolar planet to be detected by the French-led CoRoT mission, and orbits the star CoRoT-2 at a distance of 700 light years from Earth towards the constellation Aquila. Its discovery was announced on 20 December 2007. After its discovery via the transit method, its mass was confirmed via the radial velocity method.
This page describes exoplanet orbital and physical parameters.
CoRoT-7b is an exoplanet orbiting the star CoRoT-7 in the constellation of Monoceros, 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 exoplanet has a very short orbital period, revolving around its host star in about 20 hours.
CoRoT-2 is a yellow dwarf main sequence star a little cooler than the Sun. This star is located approximately 700 light-years away in the constellation of Aquila. The apparent magnitude of this star is 12, which means it is not visible to the naked eye but can be seen with a medium-sized amateur telescope on a clear dark night.
CoRoT-7 is a binary star system. The primary, CoRoT-7A is a G-type main sequence star, slightly smaller, cooler, and younger than the Sun. It has an apparent magnitude of 11.67, fainter than Proxima Centauri, the nearest star to the Sun. This star is approximately 520 light-years away from the Solar System in the constellation Monoceros.
CoRoT-6 is a magnitude 13.9 star located in the Ophiuchus constellation.
A lava planet is a type of terrestrial planet, with a surface mostly or entirely covered by molten lava. Situations where such planets could exist include a young terrestrial planet just after its formation, a planet that has recently suffered a large collision event, or a planet orbiting very close to its star, causing intense irradiation and tidal forces.
CoRoT-21b is a transiting exoplanet reportedly found by the CoRoT space telescope in 2011. Planetary parameters were published in 2012.
CoRoT-19b is a transiting exoplanet found by the CoRoT space telescope in 2011.
CoRoT-23b is a transiting Hot Jupiter exoplanet found by the CoRoT space telescope in 2011.
HAT-P-23 is a G-type main-sequence star about 1200 light-years away. It has a rapid rotation for its advanced age of 4 billion years, and exhibits a strong starspot activity. The star may be in the process of being spun up by the giant planet on close orbit. The star is enriched in heavy elements, having about 140% amount of metals compared to solar abundance.
HAT-P-21 is a G-type main-sequence star about 910 light-years away. The star has amount of metals similar to solar abundance. The survey in 2015 has failed to detect any stellar companions. The star is rotating rapidly, being spun up by the tides of giant planet on close orbit.
HAT-P-16 is a F-type main-sequence star about 740 light-years away. The star has a concentration of heavy elements slightly higher than solar abundance, and low starspot activity. The survey in 2015 have failed to find any stellar companions to it. The spectral analysis in 2014 have discovered the HAT-P-16 has a carbon to oxygen molar ratio of 0.58±0.08, close to Sun`s value of 0.55.
HD 42618 is a well-studied star with an exoplanetary companion in the equatorial constellation of Orion. With an apparent visual magnitude of 6.85 it is too faint to be readily visible to the naked eye. This system is located at a distance of 79.6 light years from the Sun based on parallax measurements. It has a relatively high proper motion, traversing the celestial sphere at an angular rate of 0.321″ per year. HD 42618 is drifting closer with a radial velocity of −53.5 km/s and is predicted to come as near as 42.6 light-years in around 297,000 years.
