Friday, 18 December 2015

Welcome to Dagon: The International Astronomical Union announces official names for 31 exoplanets.

In the past two decades a series of astronomical surveys have discovered around 2000 planets in other star systems. This has been of great interest not just to the scientific community, but also to the wider community. However naming conventions for such planets have been developed for working astrophysicists, and are less than friendly to a wider audience, with planets taking the name of the star they orbit, plus a lower case letter, b for the first planet discovered, c for the second etc. (note this number reflects the order in which planets are discovered, not the position of a planet within a stellar system). This is made more complex by the fact that only the brightest stars (and often only the brightest stars visible from the Northern Hemisphere) have names at all, others having numbers, which may derive from the constellation in which they are located (for example Alpha Centauri is the brightest star in the Centaur constellation), or from a stellar catalog, giving it a name that has no relationship to its position in the sky.

With this in mind the International Astronomical Union, the body which is responsible for naming celestial objects, launched a competition on 12 August 2015 to find names for the planets and unnamed stars of 20 stellar systems, in which the general public were asked to vote for names proposed by a variety of bodies including amateur astronomical associations, schools, universities and planetariums. The results of this competition were announced on 17 December, with names being given to 14 stars and 31 planets in 19 stellar systems (one system, Tau Boötis, was removed from the competition as the wining name was judged not to conform to International Astronomical Union rules on naming, and will be included in a later competition).

The first system renamed is 14 Andromedae, an orange giant star with a mass 2.2 times the mass of the sun 258 light years from our Solar System in the constellation of Andromeda. This is orbited every 186 days by a giant planet (14 Andromedae b) with a mass 5.33 times the time of Jupiter at a distance of 0.83 AU (i.e. 83% of the distance at which the Earth orbits the Sun). The star in this system is renamed Veritate and the planet Spe.

The second system renamed is 18 Delphini a yellow giant star 238 light years from our Solar System in the constellation of Delphinus. This is orbited every 993 days by a planet with a mass 10.3 times that of the Sun at a distance of 2.6 AU. The star in this system is renamed Musica and the planet Arion.

The third system renamed is 42 Draconis, an orange giant star with a mass roughly the same as out Sun but about 22 times its mass, 315 light years from our Solar System in the constellation of Draco. This is orbited every 479 days by a planet with a mass 3.88 times that of Jupiter at a distance of 1.19 AU. The star in this system is renamed Fafnir and the planet Orbitar.

The fourth system renamed is 47 Ursae Majoris, a yellow dwarf star similar to our Sun, 46 light years from Earth in the constellation of Ursa Major. This is orbited by two known planets, 47 Ursae Majoris b, 2.53 Jupiter mass planet orbiting every 1078 days at a distance of 2.1 AU, and 47 Ursae Majoris c, a 0.54 Jupiter mass planet orbiting every 2391 days at a distance of 3.6 AU (a third planet, Ursae Majoris d, has also been proposed). The star in this system is renamed Chalawan, while Ursae Majoris b is renamed Taphao Thong and Ursae Majoris c is named Taphao Kaew.

The fifth system renamed is 51 Pegasi, another Sun-like yellow dwarf star 50.9 light years from our Solar System in the constellation of Pegasus. This is orbited every 4.23 days by a 0.47 Jupiter mass planer at a distance of 0.53 AU. The star in this system is renamed Helvetios and the planet Dimidium.

The sixth system renamed is 55 Cancri, binary system with a yellow dwarf star similar to our Sun orbited by a smaller red dwarf at a distance of over 1000 AU, 41 light years from our Solar System in the constellation of Cancer. The principle star in this system, 55 Cancri A, is surrounded by a system of five planets; 55 Cancri b, which has a mass 0.825 times that of Jupiter and orbits every 15 days at a distance of 0.11 AU, 55 Cancri c, which has a mass 0.17 times that of Jupiter and orbits every 44 days at a distance of 0.24 AU, 55 Cancri d, which has a mass 8.82 times that of Jupiter and orbits every 5169 days at a distance of 5.74 AU, 55 Cancri e which has a mass 8.63 times that of the Earth orbits every 0.74 days at a distance of 0.016 AU and 55 Cancri f which has a mass 1.55 times that of Jupiter and orbits every 260 days at a distance of 0.78 AU.  The principle star in this system is renamed Copernicus, while 55 Cancri b is renamed Galileo, 55 Cancri c is renamed Brahe, 55 Cancri d is renamed Lippershey, 55 Cancri e is renamed Janssen and 55 Cancri f is renamed Harriot.

The seventh system renamed is Epsilon Tauri; in this instance the star, an orange giant 147 light years from the Solar System in the constellation of Taurus, is not renamed as it has an official name (Ain) already, but the planet, which has a mass 7.6 times that of our Sun and orbits every 595 days at a distance of 1.93 AU, is renamed Amateru.

The next system renamed is Iota Draconis, an orange giant star with 1.8 times the mass of the Sun and over 12 times its radius, 101 light year from the Solar System in the constellation of Draco. This star also has  name, Edasich, but again the planet, which has a mass 12.6 times that of Jupiter and orbits every 511 days at a distance of 1.27 AU, is renamed Hypatia.

The ninth system renamed is Epsilon Eridani, an orange dwarf star 10.5 light years from our Solar System in the constellation of Eridanus. This is orbited every 2502–2630 days by a 1.55 Jupiter mass planet at a distance of 3.38–3.50 AU; a second planet, an asteroid belt and an outer dust belt have also been proposed. The star in this system is renamed Ran, and the confirmed planet AEgir.

The tenth system renamed is Gamma Cephei, a binary star system comprising an orange subgiant star with a red dwarf companion orbiting at about 20 AU, 67.5 light years from Earth in the constellation of Cephus. This system already has an official name, Errai, but its planet, a 1.6 Jupiter mass body orbiting the principle star every 903 days at a distance of 2 AU, is renamed Tadmor.

The eleventh system renamed is Piscis Austrini, better known as Fomalhaut, a  young blue-white dwarf star 25 light years from Earth in the constellation of Aquarius. The name Fomalhaut is retained for this star, but its planet, a body of unknown size with an estimated orbital period of 1700 orbiting at about 177 AU is renamed Dagon.

Hubble Space Telescope image of the Fomalhaut System showing the passage of the planet now named Dagon. The system is surrounded by numerous clouds of dust and gas, as is typical for young star systems. NASA/ESA/Wikipedia.

The twelfth system renamed is HD 104985, a yellow giant star 317 light years from Earth in the constellation of Camelopardalis, with an 8.3 Jupiter mass planet orbiting every 200 days at a distance of 0.95 AU. The star in this system is renamed Tonatiuh and the planet Meztli.

The thirteenth system renamed is HD 149026, a yellow subgiant star 260 light years from Earth in the constellation of Hercules. This star has a 0.36 Jupiter mass planet orbiting every 2.88 days at a distance of 0.042 AU. The star in this system is renamed Ogma and the planet Smertrios.

The fourteenth system renamed is HD 81688 (or 41 Lyncis) a subgiant star 280 light years from Earth in the constellation of Ursa Major (it was formerly in the constellation of Lynx, hence the designation 'Lyncis'). This star has a 2.7 Jupiter mass planer orbiting every 184 days at a distance of 0.81 AU. The star in this system is named Intercrus, and the planet Arkas.

The fifteenth system renamed is Mu Arae, a yellow dwarf star similar to the Sun and 50 light years from our Solar Sytem in the constellation of Ara. This star has a system of four known planets, Mu Arae b, which has a mass 1.68 times that of Jupiter which orbits every 643 days at a distance of 1.5 AU, Mu Arae c, which has a mass 0.033 times that of Jupiter and which orbits every 9.64 days at a distance of 0.09 AU, Mu Arae d, which has a mass of 0.52 AU and which orbits every 311 days at a distance of 0.92 AU and Mu Arae e, which has a mass 1.81 times that of Jupiter and which orbits every 4206 days at a distance of 5.23 AU. The star in this system is renamed Cervantes, Mu Arae b is renamed Quijote, Mu Arae c is renamed Dulcinea, Mu Arae d is renamed Rocinante and Mu Arae e is renamed Sancho.

The sixteenth system renamed is Beta Geminorum, otherwise known as Pollux, a giant star 33.8 light years from Earth in the constellation of Gemini. This star has a well used name, and is therefore not renamed, but it has a planet with a mass 2.3 times that of Jupiter which orbits every 590 days at a distance of 1.64 AU, which is renamed Thestias.

The seventeenth system renamed is PSR 1257+12, a pulsar (highly magnetized rotating neutron stat) thought to have a mass about 1.5 times that of the Sun but a radius 0.02% of the Sun's, 2300 light years from our Solar System in the constellation of Virgo. This was the first system other than our own in which planets were discovered, with three planets, PSR 1257+12 b, which has a mass 0.02 times that of the Earth and which orbits every 25 days at a distance of 0.19 AU, PSR 1257+12 c, which has a mass 4.3 times that of the Earth and which orbits every 67 days at a distance of 0.36 AU, and PSR 1257+12 d, which has a mass 3.9 times that of the Earth and orbits every 98 days at a distance of 0.46 AU. The star in this renamed Lich, while PSR 1257+12 b becomes Draugr, PSR 1257+12 c becomes Poltergeist and PSR 1257+12 d becomes Phobetor.

The eighteenth system renamed is Upsilon Andromedae, a yellow-white dwarf star with a mass 1.27 times that of the Sun 44 light years from our Solar System in the constellation of Andromeda, with a red dwarf companion orbiting at about 750 AU. The primary star of this system has four known planets, Upsilon Andromedae Ab, which has a mass 62% of that of Jupiter and which orbits every 4.62 days at a distance of 0.0595 AU, Upsilon Andromedae Ac which has a mass 1.8 times that of Jupiter and which orbits every 241 days at a distance of 0.832 AU, Upsilon Andromedae Ad which has a mass 3.75 times that of Jupiter and which orbits every 1276 days at a distance of 2.53 AU, and Upsilon Andromedae Ae, which has a mas 96% of that of Jupiter and orbits every 3848 days at a distance of 5.25 AU. There is some doubt about the outermost of these planets, but if correct then Upsilon Andromedae Ae is the closest known analogue to Jupiter in another stellar system, both in terns of mass and orbit. The primary star in this system is renamed Titawin, while the inner three planets are named Saffar (Upsilon Andromedae Ab), Samh (Upsilon Andromedae Ac) and Majriti (Upsilon Andromedae Ad).

The final system renamed is Xi Aquilae, a red giant star 184 light years from our Solar System in the constellation of Aquila, with a 2.8 Jupiter mass planet orbiting every 137 days at a distance of 0.68 AU. The star in this system is renamed Libertas and the planet Fortitudo.

See also...

http://sciencythoughts.blogspot.co.uk/2015/11/the-possibility-of-earth-mass-planet-in.htmlThe possibility of an Earth-mass planet in the habitable zone of the Kepler-68 system.      The Kepler Space Telescope has located many multi-planet systems since its inception, which combined with discoveries made by other planet-hunting missions has enabled scientists to begin to construct models of planetary systems orbiting other stars. This is particularly complicated where not all planets are visible to the space telescope, which is only capable...
http://sciencythoughts.blogspot.co.uk/2015/11/generating-free-oxygen-in-atmosphere-of.htmlGenerating free oxygen in the atmosphere of exoplanets without the presence of life.           In the past two decades over a thousand planets have been found orbiting stars other than our own, many of which appear to be small rocky planets in the habitable zones of their stars (i.e. the zone in which such a...
http://sciencythoughts.blogspot.co.uk/2015/11/j1604217-213028-young-star-in-upper.htmlJ160421.7-213028: A young star in the Upper Scorpius Association with a possible massive planet within a protoplanetary disk. J160421.7-213028 is a young star roughly 145 parsecs (473 light years) from Earth, which forms part of the Upper Scorpius Association, making it five to ten million years old. Observations of the star with the Submillimeter Array and Atacama Large Millimeter/submillimeter Array have shown that the...
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