HD 40307 c

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HD 40307 c
Discovery
Discovered by Mayor et al.
Discovery site La Silla Observatory, Chile
Discovery dateJune 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 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.

    Contents

    Discovery

    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]

    Orbit and mass

    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]

    Characteristics

    A Trio of Super-Earths (artist's impression).jpg
    A Trio of Super-Earths (artist's impression).jpg
    HD 40307 c. Artist impression

    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.

    Trivia

    The planet was named "Problemland" in the Xkcd strip "Exoplanet Names" in August, 2013. [7]

    See also

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    <span class="mw-page-title-main">HD 40307</span> Star in the constellation Pictor

    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.

    <span class="mw-page-title-main">Discoveries of exoplanets</span> Detecting planets located outside the Solar System

    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 1 May 2023, there are 5,366 confirmed exoplanets in 3,962 planetary systems, with 856 systems having more than one planet. This is a list of the most notable discoveries.

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    <span class="mw-page-title-main">Mini-Neptune</span> Planet smaller than Neptune with a gas atmosphere

    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.

    <span class="mw-page-title-main">HD 40307 g</span> Exoplanet candidate in the constellation of Pictor

    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.

    K2-32 is a G9-type main sequence star slightly smaller and less massive than the sun. Four confirmed transiting exoplanets are known to orbit this star. A study of atmospheric escape from the planet K2-32b caused by high-energy stellar irradiation indicates that the star has always been a very slow rotator.

    References

    1. 1 2 3 4 5 6 Tuomi, Mikko; Anglada-Escudé, Guillem; Gerlach, Enrico; Jones, Hugh R. A.; Reiners, Ansgar; Rivera, Eugenio J.; Vogt, Steven S.; Butler, R. Paul (17 December 2012). "Habitable-zone super-Earth candidate in a six-planet system around the K2.5V star HD 40307". Astronomy & Astrophysics. 549: A48. arXiv: 1211.1617 . Bibcode:2013A&A...549A..48T. doi:10.1051/0004-6361/201220268. S2CID   7424216.
    2. 1 2 Mayor; et al. (2008-06-16). "Trio of 'super-Earths' discovered". BBC News. Retrieved 2008-06-16.
    3. 1 2 M. Mayor; S. Udry; C. Lovis; F. Pepe; D. Queloz; W. Benz; J.-L. Bertaux; F. Bouchy; C. Mordasini; D. Segransan (2009). "The HARPS search for southern extra-solar planets. XIII. A planetary system with 3 Super-Earths (4.2, 6.9, & 9.2 Earth masses)". Astronomy and Astrophysics. 493 (2): 639–644. arXiv: 0806.4587 . Bibcode:2009A&A...493..639M. doi:10.1051/0004-6361:200810451. S2CID   116365802.
    4. Characterizing Extrasolar Planets, Timothy M. Brown, chapter 3, Extrasolar Planets: XVI Canary Islands Winter School of Astrophysics, edited by Hans Deeg, Juan Antonio Belmonte, and Antonio Aparicio, Cambridge, UK: Cambridge University Press, 2007, ISBN   0-521-86808-4.
    5. Barnes, R.; Jackson, B.; Raymond, S.; West, A.; Greenberg, R. (2009). "The HD 40307 Planetary System: Super-Earths or Mini-Neptunes?". The Astrophysical Journal . 695 (2): 1006–1011. arXiv: 0901.1698 . Bibcode:2009ApJ...695.1006B. doi:10.1088/0004-637X/695/2/1006. S2CID   18849636.
    6. Barnes, J.; O'Brien, D. (2002). "Stability of Satellites around Close-in Extrasolar Giant Planets". The Astrophysical Journal . 575 (2): 1087–1093. arXiv: astro-ph/0205035 . Bibcode:2002ApJ...575.1087B. doi:10.1086/341477. S2CID   14508244.
    7. "Exoplanet Names".