In astronomy, stars have a variety of different stellar designations and names, including catalogue designations, current and historical proper names, and foreign language names.
Only a tiny minority of known stars have proper names; all others have only designations from various catalogues or lists, or no identifier at all. Hipparchus in the 2nd century BC enumerated about 850 naked-eye stars. Johann Bayer in 1603 listed about twice this number. Only in the 19th century did star catalogues list the naked-eye stars exhaustively. The Bright Star Catalogue, which is a star catalogue listing all stars of apparent magnitude 6.5 or brighter, or roughly every star visible to the naked eye from Earth, contains 9,096 stars. [1] The most voluminous modern catalogues list on the order of a billion stars, out of an estimated total of 200 to 400 billion in the Milky Way.
Proper names may be historical, often transliterated from Arabic or Chinese names. Such transliterations can vary so there may be multiple spellings. A smaller number of names have been introduced since the Middle Ages, and a few in modern times as nicknames have come into popular use, for example Sualocin for α Delphini and Navi for γ Cassiopeiae.
The International Astronomical Union (IAU) has begun a process to select and formalise unique proper names for the brighter naked-eye stars and for other stars of popular interest. To the IAU, name refers to the (usually colloquial) term used for a star in everyday speech, while "designation is solely alphanumerical" and used almost exclusively in official catalogues and for professional astronomy. Many of the names and some of the designations in use today were inherited from the time before the IAU existed. Other designations are being added all the time. As of the start of 2019, the IAU had decided on a little over 300 proper names, mostly for the brighter naked-eye stars. [2]
Several hundred of the brightest stars had traditional names, most of which derived from Arabic, but a few from Latin. [3] There were a number of problems with these names, however:
In 2016, the IAU organized a Working Group on Star Names (WGSN) [4] to catalog and standardize proper names for stars. The WGSN's first bulletin dated July 2016 [5] included a table of 125 stars comprising the first two batches of names approved by the WGSN (on 30 June and 20 July 2016) together with names of stars (including four traditional star names: Ain, Edasich, Errai and Fomalhaut) reviewed and adopted by the IAU Executive Committee Working Group on Public Naming of Planets and Planetary Satellites during the 2015 NameExoWorlds campaign [6] and recognized by the WGSN. Further batches of names were approved on 21 August, 12 September, 5 October and 6 November 2016. These were listed in a table of 102 stars included in the WGSN's second bulletin dated November 2016. [7] The next additions were done on 1 February 2017 (13 new star names), 30 June 2017 (29), 5 September 2017 (41), 17 November 2017 (3) and 1 June 2018 (17). All 330 names are included in the current List of IAU-approved Star Names, last updated on 1 June 2018 (with a minor correction posted on 11 June 2018). [2]
In practice, names are only universally used for the very brightest stars (Sirius, Arcturus, Vega, etc.) and for a small number of slightly less bright but "interesting" stars (Algol, Polaris, Mira, etc.). For other naked eye stars, the Bayer or Flamsteed designation is often preferred.
In addition to the traditional names, a small number of stars that are "interesting" can have modern English names. For instance, two second-magnitude stars, Alpha Pavonis and Epsilon Carinae, were assigned the proper names Peacock and Avior respectively in 1937 by Her Majesty's Nautical Almanac Office during the creation of The Air Almanac, a navigational almanac for the Royal Air Force. Of the fifty-seven stars included in the new almanac, these two had no traditional names. The RAF insisted that all of the stars must have names, so new names were invented for them. [8] These names have been approved by the IAU WGSN. [2]
The book Star Names: Their Lore and Meaning by R. H. Allen (1899) [9] has had effects on star names:
A few stars are named for individuals. These are mostly names in common use that were taken up by the scientific community at some juncture. The first such case (discounting characters from mythology) was Cor Caroli (α CVn), named in the 17th century for Charles I of England. The remaining examples are mostly named after astronomers, the best known are probably Barnard's Star (which has the highest known proper motion of any star and is thus notable even though it is far too faint to be seen with the naked eye), Kapteyn's Star and recently Tabby's Star.
The International Astronomical Union has held two NameExoWorlds contests to give proper names to exoplanets and their host stars, in 2014/5 and 2019. [10] [11] As a result, several stars were named after people, including Cervantes for Mu Arae, Copernicus for 55 Cancri A, [6] [12] and Rosalíadecastro (HD 149143) after the writer Rosalía de Castro.
In the absence of any better means of designating a star, catalogue designations are generally used. Many star catalogues are used for this purpose; see star catalogues.
The first modern schemes for designating stars systematically labelled them within their constellation.
Full-sky star catalogues detach the star designation from the star's constellation and aim at enumerating all stars with apparent magnitude greater than a given cut-off value.
Variable stars that do not have Bayer designations are assigned designations in a variable star scheme that superficially extends the Bayer scheme with uppercase Latin letters followed by constellation names, starting with single letters R to Z, and proceeding to pairs of letters. Such designations mark them as variable stars. Examples include R Cygni, RR Lyrae, and GN Andromedae. (Many variable stars also have designations in other catalogues.)
When a planet is detected around a star, the star is often given a name and number based on the name of the telescope or survey mission that discovered it and based on how many planets have already been discovered by that mission e.g. HAT-P-9, WASP-1, COROT-1, Kepler-4, TRAPPIST-1.
Star naming rights are not available for sale via the IAU or any other scientific body. Rather, star names are selected on a non-commercial basis by a small number of international organizations of astronomers, scientists, and registration bodies, who assign names consisting usually of a Greek letter followed by the star's constellation name, or less frequently based on their ancient traditional name. [15]
However, there are a number of non-scientific "star-naming" companies that offer to assign personalized nicknames to stars within their own private catalogs. [16] These names are used only by that company and are only available for viewing on their web site or on purchased items. Names by commercial entities are not recognized by the astronomical community, or by competing star-naming companies. [17] The New York City Department of Consumer Affairs has issued violation notices against companies which claimed to sell stars or the naming rights to them. [18] [19] A survey conducted by amateur astronomers discovered that just over half of consumers would still want to "name a star" with a non-scientific star-naming company even though they have been warned or informed such naming is not recognized by the astronomical community. [20]
A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. The brighter stars were assigned their first systematic names by the German astronomer Johann Bayer in 1603, in his star atlas Uranometria. Bayer catalogued only a few stars too far south to be seen from Germany, but later astronomers supplemented Bayer's catalog with entries for southern constellations.
A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the modern constellations visible from southern England. They are named for John Flamsteed who first used them while compiling his Historia Coelestis Britannica.
A star catalogue is an astronomical catalogue that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the years, and this article covers only some of the more frequently quoted ones. Star catalogues were compiled by many different ancient people, including the Babylonians, Greeks, Chinese, Persians, and Arabs. They were sometimes accompanied by a star chart for illustration. Most modern catalogues are available in electronic format and can be freely downloaded from space agencies' data centres. The largest is being compiled from the spacecraft Gaia and thus far has over a billion stars.
In ancient times, only the Sun and Moon, a few stars, and the most easily visible planets had names. Over the last few hundred years, the number of identified astronomical objects has risen from hundreds to over a billion, and more are discovered every year. Astronomers need to be able to assign systematic designations to unambiguously identify all of these objects, and at the same time give names to the most interesting objects, and where relevant, features of those objects.
All stars but one can be associated with an IAU constellation. IAU constellations are areas of the sky. Although there are only 88 IAU constellations, the sky is actually divided into 89 irregularly shaped boxes as the constellation Serpens is split into two separate sections, Serpens Caput to the west and Serpens Cauda to the east.
Denebola is the second-brightest individual star in the zodiac constellation of Leo. It is the easternmost of the bright stars of Leo. It has the Bayer designation Beta Leonis or β Leonis, which are abbreviated Beta Leo or β Leo. Denebola is an A-type main sequence star with 75% more mass than the Sun and 15 times the Sun's luminosity. Based on parallax measurements from the Hipparcos astrometry satellite, the star is at a distance of 36 light-years from the Sun. Its apparent visual magnitude is 2.14, making it readily visible to the naked eye. Denebola is a Delta Scuti type variable star, meaning its luminosity varies very slightly over a period of a few hours.
Epsilon Carinae, officially named Avior, is a binary star in the southern constellation of Carina. At apparent magnitude +1.86 it is one of the brightest stars in the night sky, but is not visible from most of the northern hemisphere. The False Cross is an asterism formed of Delta Velorum, Kappa Velorum, Iota Carinae and ε Carinae. It is so called because it is sometimes mistaken for the Southern Cross, causing errors in astronavigation.
Epsilon Tauri or ε Tauri, formally named Ain, is an orange giant star located approximately 146 light-years from the Sun in the constellation of Taurus. An exoplanet is believed to be orbiting the star.
41 Arietis is a triple star system in the northern constellation of Aries. With an apparent visual magnitude of 3.63, this system is readily visible to the naked eye. It has an annual parallax shift of 19.69 mas, which indicates it is at a distance of 166 light-years from the Sun.
Beta1 Sagittarii, Latinized from β1 Sagittarii, is a binary star system in the zodiac constellation of Sagittarius, next to the southern constellation border with Telescopium. The brighter primary is named Arkab Prior, the traditional name of the system. It is visible to the naked eye with a combined apparent visual magnitude of +4.01. Based upon an annual parallax shift of 10.40 mas as seen from Earth, it is located roughly 310 light-years from the Sun. At Beta1 Sagittarii's distance, the visual magnitude is diminished by an extinction factor of 0.17 due to interstellar dust.
Kappa Serpentis, Latinised from κ Serpentis, is a single, red-hued star in the constellation Serpens, in its head. It has the proper name Gudja and the Flamsteed designation 35 Serpentis. This star is visible to the naked eye with an apparent visual magnitude of +4.09. It is located approximately 383 light years from the Sun, based on parallax, and is drifting closer with a radial velocity of −38 km/s.
Xi Andromedae, officially named Adhil, is a solitary star in the northern constellation of Andromeda. It has an apparent magnitude of +4.9. Based on parallax measurements obtained during the Gaia mission, it lies at a distance of roughly 223 light-years from the Sun.
14 Andromedae, abbreviated 14 And, also named Veritate, is a single, orange-hued giant star situated approximately 247 light-years away in the northern constellation of Andromeda. It is dimly visible to the naked eye with an apparent visual magnitude of 5.22. The star is moving closer to the Earth with a heliocentric radial velocity of −60 km/s. In 2008 an extrasolar planet was discovered to be orbiting the star.
38 Boötis is a single star in the northern constellation of Boötes, located approximately 157 light years from the Sun. It has the traditional name Merga and the Bayer designation h Boötis; 38 Boötis is the star's Flamsteed designation. This object is visible to the naked eye as a dim, yellow-white hued star with an apparent visual magnitude of 5.76. It is moving closer to the Earth with a heliocentric radial velocity of −4.5 km/s.
Beta Piscium or β Piscium, formally named Fumalsamakah, is a blue-white hued star in the zodiac constellation of Pisces. Its apparent magnitude is 4.40, meaning it can be faintly seen with the naked eye. Based on parallax measurements taken during the Hipparcos mission, it is about 410 light-years distant from the Sun.
λ Ophiuchi, Latinized as Lambda Ophiuchi, is a triple star system in the equatorial constellation of Ophiuchus. It has the traditional name Marfik, which now applies exclusively to the primary component. The system is visible to the naked eye as a faint point of light with an apparent visual magnitude of 3.82. It is located approximately 173 light-years from the Sun, based on its parallax, but is drifting closer with a radial velocity of –16 km/s.
31 Lyncis is the fourth-brightest star in the constellation of Lynx. It has the traditional name Alsciaukat, pronounced. The orange-hued star is visible to the naked eye with a baseline apparent visual magnitude of +4.25. It is a single star located about 380 light years away from the Sun, based on parallax, and is moving further away with a heliocentric radial velocity of +25 km/s.
Theta Columbae, also named Elkurud, is a solitary star in the southern constellation of Columba. It is faintly visible to the naked eye, having an apparent visual magnitude of 5.02. Based upon parallax measurements taken during the Hipparcos mission, it is roughly 720 light-years distant from the Sun. At its present distance, the visual magnitude of the star is reduced by an interstellar extinction factor of 0.11. It is currently moving away from the Sun with a radial velocity of 45.3 km/s. The star made its closest approach about 4.7 million years ago when it underwent perihelion passage at a distance of 10.9 ly (3.33 pc).
The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education, Outreach and Heritage.
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