Stellar designation

Designations of stars (and other celestial bodies) is mediated by the International Astronomical Union (IAU). Many of the star names in use today were inherited from the time before the IAU existed. Other names, mainly for variable stars (including novae and supernovae), are being added all the time.

Approximately 10,000 stars are visible to the naked eye.[1] Pre-modern catalogues listed only the brightest of these. Hipparchus in the 2nd century BC enumerated about 850 stars. Johann Bayer in 1603 listed about twice this number. Only a minority of these have proper names; all others are designated by numbers from various catalogues. Only in the 19th century did star catalogues list the naked-eye stars exhaustively. 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

Several hundred of the brightest stars have traditional names, most of which derive from Arabic, but a few from Latin.[2]

There are a number of problems with these names, however:

In practice, the traditional 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 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 Barnard's star 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. See stars named after people.

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 classical names. The RAF insisted that all of the stars must have names, so new names were invented for them.[3]

The book Star Names: Their Lore and Meaning by R.H.Allen (1899)[4] has had effects on star names:

A few stars are named for individuals. These are mostly unofficial names that became official at some juncture. The first such case (discounting characters from Greek mythology) was Cor Caroli (α CVn), named in the 17th century for Charles I of England. The remaining examples are mostly stars named after astronomers or astronauts.

Catalogue numbers

In the absence of any better means of designating a star, catalogue numbers are generally used. Many star catalogues are used for this purpose; see star catalogues.

By constellation

The first modern schemes for designating stars systematically labelled them within their constellation.

Full-sky catalogues

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 designations

Variable stars that do not have Bayer designations are assigned designations in a variable star scheme that superficially extends the Bayer scheme. Such designations mark them as variable stars. (Many variable stars also have designations in other catalogues.)

Exoplanet searches

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.

Sale of star names

There are a number of companies that sell naming rights to obscure stars for commemorative purposes. These sales of star names are not recognised by astronomers, nor by any international scientific or registration body. As a result, a single star can potentially be named independently by multiple companies or multiple times by the same company.[5]

See also

References

  1. Under average conditions, about 5,600 stars brighter than magnitude +6 are visible to the naked eye; theoretically, under perfect conditions, about 45,000 stars brighter than magnitude +8 would be visible.
  2. The NASA in 1971 compiled a "technical memorandum" collecting a total of 537 named stars. Rhoads, J. W.,Technical Memorandum 33-507 – A Reduced Star Catalog Containing 537 Named Stars, NASA-CR-124573 (1971).
  3. Sadler, Donald H. (2008). "A Personal History of H.M. Nautical Almanac Office" (PDF). United Kingdom Hydrographic Office. Retrieved 2010-09-26.
  4. Richard Hinckley Allen (1963-06-01). Star Names: Their Lore and Meaning. Dover Publications. ISBN 978-0486210797.
  5. Andersen, Johannes. "Buying Stars and Star Names". International Astronomical Union. Retrieved 2013-06-04.

External links

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