Discovery | |
---|---|
Discovered by | Mayor et al. |
Discovery site | La Silla Observatory, Chile |
Discovery date | June 16, 2008 |
radial velocity, using HARPS | |
Orbital characteristics | |
0.07990.07590.0839 AU | |
Eccentricity | 0.0500.13 [1] |
9.61849.61359.6234 [1] d | |
Semi-amplitude | 2.452.172.75 [1] |
Star | HD 40307 |
HD 40307 c is an extrasolar planet orbiting the star HD 40307, located 42 light-years away in the direction of the southern constellation of Pictor. The planet was discovered by the radial velocity method, using the HARPS apparatus, in June 2008. Of the six proposed planets in the HD 40307 star system, it is the third-largest, and has the second-closest orbit from the star. [1] The planet is of interest as this star has relatively low metallicity, supporting a hypothesis that different metallicities in protostars determine what kind of planets they will form.
Like the other two exoplanets, HD 40307 b and HD 40307 d, orbiting the star HD 40307, HD 40307 c was discovered by measuring variations in the radial velocity of HD 40307 caused by the star's orbit around the center of mass of the planetary system. These measurements were made by the High Accuracy Radial Velocity Planet Searcher spectrograph apparatus (HARPS) at the La Silla Observatory in Chile's Atacama Desert. [2] The discovery of planets in the HD 40307 system was announced in an astrophysics convention that took place in Nantes, France in mid-June 2008. [2]
HD 40307 c is the third-most massive planet in the system, with a lower mass bound 6.8 times the mass of the Earth. [1] The planet orbits HD 40307 at about 0.08 astronomical units (AU), as compared to the Earth's distance from the Sun at 1 AU; as a result, one year on the planet constitutes approximately 9.6 Earth days. Analysis of the radial velocity data used to detect the planet does not yield a statistically significant deviation from a circular orbit. [3]
The star around which the planet HD 40307 orbits has a low metallicity, unusual when compared to other planet-bearing stars. This supports a hypothesis concerning the possibility that the metallicity of stars during their births may determine whether a protostar's accretion disk forms gas giants or terrestrial planets. [3]
HD 40307 c has not been observed directly and likely does not transit. [1] More specific characteristics (such as surface temperature, composition and radius) cannot be determined. [4]
HD 40307 c has a small mass of at least 6.9 times Earth's, so it was first assumed terrestrial. Later in 2009 a study stated that if HD 40307 c is terrestrial, tidal heating would destabilise it, in a manner greater than this process crushes the Jovian moon Io. Such restrictions as bind terrestrial planets would not restrict ice giant planets like Neptune or Uranus. HD 40307 c might be a sub-Neptune. [5]
Since the same tides are predicted to result in the destruction of larger natural satellites of planets located close to their parent star, [6] it is unlikely that HD 40307 c hosts any satellites.
The planet was named "Problemland" in the Xkcd strip "Exoplanet Names" in August, 2013. [7]
HD 114386 is a star with a pair of orbiting exoplanets in the southern constellation of Centaurus. It has an apparent visual magnitude of 8.73, which means it cannot be viewed with the naked eye but can be seen with a telescope or good binoculars. Based on parallax measurements, the system is located at a distance of 91 light years from the Sun. It is receding with a radial velocity of 33.4 km/s. The star shows a high proper motion, traversing the celestial sphere at an angular rate of 0.318 arcsec yr−1.
HD 102195 is an orange-hued star in the zodiac constellation of Virgo with a confirmed exoplanet companion. With an apparent visual magnitude of 8.07, the star is too faint to be seen with the naked eye. The distance to HD 102195 can be estimated from its annual parallax shift of 34.06 mas, yielding 95.8 light years. It is moving further away from the Earth with a heliocentric radial velocity of 1.85 km/s. This is a high proper motion star and a possible member of the η Cha stellar kinematic group.
Mu Arae c, also known as HD 160691 c, formally named Dulcinea, is an extrasolar planet orbiting the star Mu Arae of the constellation Ara. It was the first 'hot Neptune' to be discovered.
A Super-Earth or super-terran is a type of exoplanet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively. The term "super-Earth" refers only to the mass of the planet, and so does not imply anything about the surface conditions or habitability. The alternative term "gas dwarfs" may be more accurate for those at the higher end of the mass scale, although "mini-Neptunes" is a more common term.
HD 219828 is a star with two exoplanetary companions in the constellation of Pegasus. With an apparent visual magnitude of 8.04, it is an eighth magnitude star that is too dim to be readily visible to the naked eye. The star is located at a distance of approximately 237 light years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −24 km/s.
This page describes exoplanet orbital and physical parameters.
HD 181433 is a star with a system of orbiting exoplanets located in the southern constellation of Pavo. With an apparent visual magnitude of 8.40, it is too faint to be visible to the naked eye. It lies at a distance of 88 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of +40 km/s. The system shows a high proper motion, traversing the celestial sphere at an angular rate of 0.340 arcsec yr−1.
HD 40307 is an orange (K-type) main-sequence star located approximately 42 light-years away in the constellation of Pictor, taking its primary name from its Henry Draper Catalogue designation. It is calculated to be slightly less massive than the Sun. The star has six known planets, three discovered in 2008 and three more in 2012. One of them, HD 40307 g, is a potential super-Earth in the habitable zone, with an orbital period of about 200 days. This object might be capable of supporting liquid water on its surface, although much more information must be acquired before its habitability can be assessed.
HD 40307 b is an extrasolar planet orbiting the star HD 40307, located 42 light-years away in the direction of the southern constellation Pictor. The planet was discovered by the radial velocity method, using the European Southern Observatory's HARPS apparatus, in June 2008. It is the second smallest of the planets orbiting the star, after HD 40307 e. The planet is of interest as this star has relatively low metallicity, supporting a hypothesis that different metallicities in protostars determine what kind of planets they will form.
HD 40307 d is an extrasolar planet orbiting the star HD 40307, located 42 light-years from Earth in the direction of the southern constellation Pictor. The planet was discovered by the radial velocity method, using the HARPS apparatus in June 2008. It is the most massive of the six proposed planets in the system. The planet is of interest as this star has relatively low metallicity, supporting a hypothesis that different metallicities in protostars determine what kind of planets they will form.
HD 47186 is a star with a pair of orbiting exoplanets in the southern constellation of Canis Major. The system is located at a distance of 122 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of 4.2 km/s. Although it has an absolute magnitude of 4.64, at the distance of this system the apparent visual magnitude is 7.63; too faint to be seen with the naked eye. It has a high proper motion, traversing the celestial sphere at an angular rate of 0.272″·yr−1.
HD 171238 is a star with an orbiting exoplanet in the southern constellation of Sagittarius. It is located at a distance of 145 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of 21 km/s. The star has an absolute magnitude of 5.15, but at the distance of this system it is too faint to be viewed with the naked eye, having an apparent visual magnitude of 8.61.
An exoplanet is a planet located outside the Solar System. The first evidence of an exoplanet was noted as early as 1917, but was not recognized as such until 2016; no planet discovery has yet come from that evidence. What turned out to be the first detection of an exoplanet was published among a list of possible candidates in 1988, though not confirmed until 2003. The first confirmed detection came in 1992, with the discovery of terrestrial-mass planets orbiting the pulsar PSR B1257+12. The first confirmation of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet was found in a four-day orbit around the nearby star 51 Pegasi. Some exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods, such as the transit method and the radial-velocity method. As of 24 July 2024, there are 7,026 confirmed exoplanets in 4,949 planetary systems, with 1007 systems having more than one planet. This is a list of the most notable discoveries.
HD 20781 is a star which is part of a wide binary system with HD 20782. The companion star has a very large angular separation of 252 arcsec, corresponding to 9080 AU at the distance of HD 20782. Both stars possess their own planetary systems in S type orbits, with a total of five known planets around both stars. This is the first known example of planets being found orbiting both components of a wide binary system. HD 20781 has no noticeable starspot activity.
A Mini-Neptune is a planet less massive than Neptune but resembling Neptune in that it has a thick hydrogen-helium atmosphere, probably with deep layers of ice, rock or liquid oceans.
HD 40307 g is an exoplanet candidate suspected to be orbiting in the habitable zone of HD 40307. It is located 42 light-years away in the direction of the southern constellation Pictor. The planet was discovered by the radial velocity method, using the European Southern Observatory's HARPS apparatus by a team of astronomers led by Mikko Tuomi at the University of Hertfordshire and Guillem Anglada-Escude of the University of Göttingen, Germany.
HD 40307 e is an extrasolar planet candidate suspected to be orbiting the star HD 40307. It is located 42 light-years away in the direction of the southern constellation Pictor. The planet was discovered by the radial velocity method, using the European Southern Observatory's HARPS apparatus by a team of astronomers led by Mikko Tuomi at the University of Hertfordshire and Guillem Anglada-Escude of the University of Göttingen, Germany.
HD 40307 f is an extrasolar planet orbiting the star HD 40307. It is located 42 light-years away in the direction of the southern constellation Pictor. The planet was discovered by the radial velocity method, using the European Southern Observatory's HARPS apparatus by a team of astronomers led by Mikko Tuomi at the University of Hertfordshire and Guillem Anglada-Escude of the University of Göttingen, Germany. The existence of planet was confirmed in 2015.
HD 109271 is a wide binary star system in the constellation of Virgo. The brighter member of the binary has a pair of orbiting exoplanets. With an apparent visual magnitude of 8.05, it cannot be seen with the naked eye. Parallax measurements made by Gaia put the star at a distance of 181 light-years away from the Sun, but it is drifting closer with a radial velocity of −5 km/s. The system shows a high proper motion, traversing the celestial sphere at an angular rate of 0.232 arcsec yr−1.