
A Bayer designation is a
stellar designation
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 ...
in which a specific
star
A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...
is identified by a
Greek
Greek may refer to:
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group
*Greek language, a branch of the Indo-European language family
**Proto-Greek language, the assumed last common ancestor of all kno ...
or
Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
letter followed by the
genitive
In grammar, the genitive case ( abbreviated ) is the grammatical case that marks a word, usually a noun, as modifying another word, also usually a noun—thus indicating an attributive relationship of one noun to the other noun. A genitive can ...
form of its parent constellation's Latin name. The original list of Bayer designations contained 1564 stars. The brighter stars were assigned their first systematic names by the German
astronomer
An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...
Johann Bayer
Johann Bayer (; 1572 – 7 March 1625) was a German lawyer and uranographer (celestial cartographer). He was born in Rain in 1572. In 1592, aged 20, he began his study of philosophy and law at the University of Ingolstadt, after which he ...
in 1603, in his star atlas ''
Uranometria
is a star atlas produced by Johann Bayer. It was published in Augsburg in 1603 by Christoph Mang (''Christophorus Mangus'') under the full title (from Latin: ''Uranometria, containing charts of all the constellations, drawn by a new method an ...
''. Bayer catalogued only a few stars too far south to be seen from Germany, but later astronomers (including
Nicolas-Louis de Lacaille
Abbé Nicolas-Louis de Lacaille (; 15 March 171321 March 1762), formerly sometimes spelled de la Caille, was a kingdom of France, French astronomer and geodesist who named 14 out of the IAU designated constellations, 88 constellations. From 1750 ...
and
Benjamin Apthorp Gould
Benjamin Apthorp Gould (September 27, 1824 – November 26, 1896) was a pioneering American astronomer. He is noted for creating the ''Astronomical Journal'', discovering the Gould Belt, and for founding of the Argentine National Observatory and ...
) supplemented Bayer's catalog with entries for southern constellations.
Scheme
Bayer assigned a lowercase
Greek letter
The Greek alphabet has been used to write the Greek language since the late 9th or early 8th century BC. It was derived from the earlier Phoenician alphabet, and is the earliest known alphabetic script to systematically write vowels as wel ...
(alpha (α), beta (β), gamma (γ), etc.) or a Latin letter (A, b, c, etc.) to each star he catalogued, combined with the Latin name of the star's parent constellation in
genitive
In grammar, the genitive case ( abbreviated ) is the grammatical case that marks a word, usually a noun, as modifying another word, also usually a noun—thus indicating an attributive relationship of one noun to the other noun. A genitive can ...
(possessive) form. The constellation name is frequently abbreviated to a standard three-letter form. For example,
Aldebaran
Aldebaran () is a star in the zodiac constellation of Taurus. It has the Bayer designation α Tauri, which is Latinized to Alpha Tauri and abbreviated Alpha Tau or α Tau. Aldebaran varies in brightness from an apparent vis ...
in the constellation
Taurus
Taurus is Latin for 'bull' and may refer to:
* Taurus (astrology), the astrological sign
** Vṛṣabha, in vedic astrology
* Taurus (constellation), one of the constellations of the zodiac
* Taurus (mythology), one of two Greek mythological ch ...
(the Bull) is designated ''α Tauri'' (abbreviated ''α Tau'', pronounced ''Alpha Tauri''), which means "Alpha of the Bull".
Bayer used Greek letters for the brighter stars, but the Greek alphabet has only twenty-four letters, while a single constellation may contain fifty or more stars visible to the naked eye. When the Greek letters ran out, Bayer continued with Latin letters: uppercase ''A'', followed by lowercase ''b'' through ''z'' (omitting ''j'' and ''v'', but ''o'' was included), for a total of another 24 letters.
Bayer did not label "permanent" stars with uppercase letters (except for ''A'', which he used instead of ''a'' to avoid confusion with ''α''). However, a number of stars in southern constellations have uppercase letter designations, like
B Centauri The Bayer designations b Centauri and B Centauri are distinct. Due to technical limitations, both designations link here. For the star
* b Centauri, see HD 129116
* B Centauri, see HD 102964
See also
* β Centauri
Beta Centau ...
and
G Scorpii
G Scorpii (abbreviated G Sco), also named Fuyue, is a giant star in the constellation of Scorpius. It has an apparent magnitude of +3.19. It is approximately 126 light-years from the Sun.
Nomenclature
''G Scorpii'' is the star's Bayer ...
. These letters were assigned by later astronomers, notably Lacaille in his ''Coelum Australe Stelliferum'' and Gould in his ''Uranometria Argentina''. Lacaille followed Bayer's use of Greek letters, but this was insufficient for many constellations. He used first the lowercase letters, starting with ''a'', and if needed the uppercase letters, starting with ''A'', thus deviating somewhat from Bayer's practice. Lacaille used the Latin alphabet three times over in the large constellation
Argo Navis
Argo Navis (the Ship Argo), or simply Argo, is one of Ptolemy's 48 constellations, now a grouping of three IAU constellations. It is formerly a single large constellation in the southern sky. The genitive is "Argus Navis", abbreviated "Arg". ...
, once for each of the three areas that are now the constellations of
Carina
Carina may refer to:
Places
Australia
* Carina, Queensland, a suburb in Brisbane
* Carina Heights, Queensland, a suburb in Brisbane
* Carina, Victoria, a locality in Mildura
Serbia
* Carina, Osečina, a village in the Kolubara District
...
,
Puppis
Puppis ("poop deck, stern") is a constellation in the southern sky. It was originally part of the Former constellations, traditional constellation of Argo Navis (the ship of Jason and the Argonauts), which was divided into three parts, the other ...
and
Vela. That was still insufficient for the number of stars, so he also used uppercase Latin letters such as
N Velorum and
Q Puppis The Bayer designation
A Bayer designation is a stellar designation in which a specific star is identified by a Greek alphabet, Greek or Latin letter followed by the genitive case, genitive form of its parent constellation's Latin name. The origina ...
. Lacaille assigned uppercase letters between R and Z in several constellations, but these have either been dropped to allow the assignment of those letters to variable stars or have actually turned out to be variable.
Order by magnitude class
In most constellations, Bayer assigned Greek and Latin letters to stars within a constellation in rough order of
apparent brightness
Apparent magnitude () is a measure of the brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction of the object's light cau ...
, from brightest to dimmest. The order is not necessarily a precise labeling from brightest to dimmest: in Bayer's day stellar brightness could not be measured precisely. Instead, stars were traditionally assigned to one of six magnitude classes (the brightest to first magnitude, the dimmest to sixth), and Bayer typically ordered stars within a constellation by class: all the first-magnitude stars (in some order), followed by all the second-magnitude stars, and so on. Within each magnitude class, Bayer made no attempt to arrange stars by relative brightness.
[ See p. 192.] As a result, the brightest star in each class did not always get listed first in Bayer's order—and the brightest star overall did not necessarily get the designation "Alpha". A good example is the constellation
Gemini
Gemini most often refers to:
* Gemini (constellation), one of the constellations of the zodiac
* Gemini (astrology), an astrological sign
Gemini may also refer to:
Science and technology Space
* Gemini in Chinese astronomy, the Gemini constellat ...
, where
Pollux is Beta Geminorum and the slightly dimmer
Castor
Castor most commonly refers to:
*Castor (star), a star in the Gemini constellation
*Castor, one of the Dioscuri/Gemini twins Castor and Pollux in Greco-Roman mythology
Castor or CASTOR may also refer to:
Science and technology
*Castor (rocket s ...
is Alpha Geminorum.
In addition, Bayer did not always follow the magnitude class rule; he sometimes assigned letters to stars according to their location within a constellation, or the order of their rising, or to historical or mythological details. Occasionally the order looks quite arbitrary.
Of the 88 modern constellations, there are at least 30 in which Alpha is not the brightest star, and four of those lack a star labeled "Alpha" altogether. The constellations with no Alpha-designated star include
Vela and
Puppis
Puppis ("poop deck, stern") is a constellation in the southern sky. It was originally part of the Former constellations, traditional constellation of Argo Navis (the ship of Jason and the Argonauts), which was divided into three parts, the other ...
—both formerly part of
Argo Navis
Argo Navis (the Ship Argo), or simply Argo, is one of Ptolemy's 48 constellations, now a grouping of three IAU constellations. It is formerly a single large constellation in the southern sky. The genitive is "Argus Navis", abbreviated "Arg". ...
, whose Greek-letter stars were split among three constellations.
Canopus
Canopus is the brightest star in the southern constellation of Carina (constellation), Carina and the list of brightest stars, second-brightest star in the night sky. It is also Bayer designation, designated α Carinae, which is Rom ...
, the former α Argus, is now α Carinae in the modern constellation
Carina
Carina may refer to:
Places
Australia
* Carina, Queensland, a suburb in Brisbane
* Carina Heights, Queensland, a suburb in Brisbane
* Carina, Victoria, a locality in Mildura
Serbia
* Carina, Osečina, a village in the Kolubara District
...
.
Norma's Alpha and Beta were reassigned to
Scorpius
Scorpius is a zodiac constellation located in the Southern celestial hemisphere, where it sits near the center of the Milky Way, between Libra to the west and Sagittarius to the east. Scorpius is an ancient constellation whose recognition pred ...
and re-designated
N and
H Scorpii respectively, leaving Norma with no Alpha.
Francis Baily
Francis Baily (28 April 177430 August 1844) was an English astronomer. He is most famous for his observations of " Baily's beads" during a total eclipse of the Sun. Baily was also a major figure in the early history of the Royal Astronomical S ...
died before designating an Alpha in
Leo Minor
Leo Minor is a small and faint constellation in the northern celestial hemisphere. Its name is Latin for "the smaller lion", in contrast to Leo, the larger lion. It lies between the larger and more recognizable Ursa Major to the north and Leo ...
, so it also has no Alpha. (The star
46 Leonis Minoris
46 Leonis Minoris (abbreviated 46 LMi), also named Praecipua , is the brightest star in the constellation of Leo Minor. It is of spectral class K0+III-IV and of magnitude 3.83. It is a red clump giant. Based upon parallax measurements, its ...
would have been the obvious candidate.)
Orion as an example
In
Orion
Orion may refer to:
Common meanings
* Orion (constellation), named after the mythical hunter
* Orion (mythology), a hunter in Greek mythology
Arts and media
Fictional entities Characters and species
* Orion (character), a DC Comics c ...
, Bayer first designated
Betelgeuse
Betelgeuse is a red supergiant star in the constellation of Orion (constellation), Orion. It is usually the List of brightest stars, tenth-brightest star in the night sky and, after Rigel, the second brightest in its constellation. It i ...
and
Rigel
Rigel is a blue supergiant star in the constellation of Orion. It has the Bayer designation β Orionis, which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori. Rigel is the brightest and most massive componentand ...
, the two 1st-magnitude stars (those of magnitude 1.5 or less), as Alpha and Beta from north to south, with Betelgeuse (the shoulder) coming ahead of Rigel (the foot), even though the latter is usually the brighter. (Betelgeuse is a variable star and can at its maximum occasionally outshine Rigel.)
Bayer then repeated the procedure for the stars of the 2nd magnitude, labeling them from ''gamma'' through ''zeta'' in "top-down" (north-to-south) order. Letters as far as Latin ''p'' were used for stars of the sixth magnitude.
Bayer's miscellaneous labels
Although Bayer did not use uppercase Latin letters (except ''A'') for "fixed stars", he did use them to label other items shown on his charts, such as neighboring constellations, "temporary stars", miscellaneous astronomical objects, or reference lines like the Tropic of Cancer.
In
Cygnus, for example, Bayer's fixed stars run through ''g'', and on this chart Bayer employs ''H'' through ''P'' as miscellaneous labels, mostly for neighboring constellations. Bayer did not intend such labels as catalog designations, but some have survived to refer to astronomical objects:
P Cygni
P Cygni (34 Cygni) is a variable star in the constellation Cygnus. The designation "P" was originally assigned by Johann Bayer in '' Uranometria'' as a nova. Located about 5,300 light-years (1,560 parsecs) from Earth, it is a hypergian ...
for example is still used as a designation for Nova Cyg 1600. Tycho's Star (
SN 1572
SN 1572 ('' Tycho's Star'', ''Tycho's Nova'', ''Tycho's Supernova''), or B Cassiopeiae (B Cas), was a supernova of Type Ia in the constellation Cassiopeia, one of eight supernovae visible to the naked eye in historical records. It appeared in e ...
), another "temporary star", appears as B Cassiopeiae. In charts for constellations that did not exhaust the Greek letters, Bayer sometimes used the leftover Greek letters for miscellaneous labels as well.
Revised designations
Ptolemy
Claudius Ptolemy (; , ; ; – 160s/170s AD) was a Greco-Roman mathematician, astronomer, astrologer, geographer, and music theorist who wrote about a dozen scientific treatises, three of which were important to later Byzantine science, Byzant ...
designated four stars as "border stars", each shared by two constellations:
Alpheratz
Alpheratz is a prominent star system in the constellation of Andromeda. Pronounced , it has the Bayer designation Alpha Andromedae, Latinised from α Andromedae, and abbreviated Alpha And or α And, respectively. Alpheratz is the ...
(in
Andromeda and
Pegasus
Pegasus (; ) is a winged horse in Greek mythology, usually depicted as a white stallion. He was sired by Poseidon, in his role as horse-god, and foaled by the Gorgon Medusa. Pegasus was the brother of Chrysaor, both born from Medusa's blood w ...
),
Elnath
Beta Tauri is the second-brightest star in the constellation of Taurus. It has the official name Elnath; ''Beta Tauri'' is the current Bayer designation, which is Latinised from β Tauri and abbreviated Beta Tau or β Tau. The original ...
(in
Taurus
Taurus is Latin for 'bull' and may refer to:
* Taurus (astrology), the astrological sign
** Vṛṣabha, in vedic astrology
* Taurus (constellation), one of the constellations of the zodiac
* Taurus (mythology), one of two Greek mythological ch ...
and
Auriga
Auriga is a constellation in the northern celestial hemisphere. It is one of the 88 modern constellations; it was among the 48 constellations listed by the 2nd-century astronomer Ptolemy. Its name is Latin for '(the) charioteer', associating i ...
),
Nu Boötis (
Nu1 and
Nu2)(in
Boötes
Boötes ( ) is a constellation in the northern sky, located between 0° and +60° declination, and 13 and 16 hours of right ascension on the celestial sphere. The name comes from , which comes from 'herder, herdsman' or 'plowman' (literally, 'o ...
and
Hercules
Hercules (, ) is the Roman equivalent of the Greek divine hero Heracles, son of Jupiter and the mortal Alcmena. In classical mythology, Hercules is famous for his strength and for his numerous far-ranging adventures.
The Romans adapted the Gr ...
) and
Fomalhaut
Fomalhaut (, ) is the brightest star in the southern constellation of Piscis Austrinus, the Southern Fish, and one of the brightest stars in the night sky. It has the Bayer designation Alpha Piscis Austrini, which is an alternative ...
(in
Piscis Austrinus
Piscis Austrinus is a constellation in the southern celestial hemisphere. The name is Latin for "the southern fish", in contrast with the larger constellation Pisces, which represents a pair of fish. Before the 20th century, it was also known as ...
and
Aquarius).
Bayer assigned the first three of these stars a Greek letter from both constellations: , , and . (He catalogued Fomalhaut only once, as
Alpha Piscis Austrini
Fomalhaut (, ) is the brightest star in the southern constellation of Piscis Austrinus, the Southern Fish, and one of the brightest stars in the night sky. It has the Bayer designation Alpha Piscis Austrini, which is an alternative ...
.) When the
International Astronomical Union
The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
(IAU) assigned definite boundaries to the constellations in 1930, it declared that stars and other celestial objects can belong to only one constellation. Consequently, the redundant second designation in each pair above has dropped out of use.
Bayer assigned two stars duplicate names by mistake: (duplicated as ) and (
Kappa1 and
Kappa2) (duplicated as ). He corrected these in a later atlas, and the duplicate names were no longer used.
Other cases of multiple Bayer designations arose when stars named by Bayer in one constellation were transferred by later astronomers to a different constellation. Bayer's Gamma and Omicron Scorpii, for example, were later reassigned from
Scorpius
Scorpius is a zodiac constellation located in the Southern celestial hemisphere, where it sits near the center of the Milky Way, between Libra to the west and Sagittarius to the east. Scorpius is an ancient constellation whose recognition pred ...
to
Libra
Libra generally refers to:
* Libra (constellation), a constellation
* Libra (astrology), an astrological sign based on the star constellation
Libra may also refer to:
Arts and entertainment
* ''Libra'' (novel), a 1988 novel by Don DeLillo
Musi ...
and given the new names
Sigma
Sigma ( ; uppercase Σ, lowercase σ, lowercase in word-final position ς; ) is the eighteenth letter of the Greek alphabet. In the system of Greek numerals, it has a value of 200. In general mathematics, uppercase Σ is used as an operator ...
and
Upsilon Librae.
(To add to the confusion, the star now known as
Omicron Scorpii was not named by Bayer but was assigned the designation o Scorpii (Latin lowercase 'o') by Lacaille—which later astronomers misinterpreted as omicron once Bayer's omicron had been reassigned to Libra.)
A few stars no longer lie (according to the modern constellation boundaries) within the constellation for which they are named. The
proper motion
Proper motion is the astrometric measure of changes in the apparent places of stars or other celestial objects as they move relative to the center of mass of the Solar System. It is measured relative to the distant stars or a stable referenc ...
of
Rho Aquilae, for example, carried it across the boundary into
Delphinus
Delphinus is a small constellation in the Northern Celestial Hemisphere, close to the celestial equator. Its name is the Latin version for the Greek word for dolphin (). It is one of the 48 constellations listed by the 2nd-century astronomer Pt ...
in 1992.
A further complication is the use of numeric superscripts to distinguish neighboring stars that Bayer (or a later astronomer) labeled with a common letter. Usually these are
double star
In observational astronomy, a double star or visual double is a pair of stars that appear close to each other as viewed from Earth, especially with the aid of optical telescopes.
This occurs because the pair either forms a binary star (i.e. a ...
s (mostly optical doubles rather than true
binary star
A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars us ...
s), but there are some exceptions such as the chain of stars
π1,
π2,
π3,
π4,
π5 and
π6 Orionis. The most stars given the same Bayer designation but with an extra number attached to it is
Psi Aurigae. (
ψ1,
ψ2,
ψ3,
ψ4,
ψ5,
ψ6,
ψ7,
ψ8,
ψ9,
ψ10, although according to the modern IAU constellation boundaries, ψ
10 lies in
Lynx
A lynx ( ; : lynx or lynxes) is any of the four wikt:extant, extant species (the Canada lynx, Iberian lynx, Eurasian lynx and the bobcat) within the medium-sized wild Felidae, cat genus ''Lynx''. The name originated in Middle Engl ...
).
See also
*
Flamsteed designation
A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the 88 modern constellations, modern constellations visible from southern England. They are named after John Flamsteed, au ...
*
Gould designation Gould designations for stars are similar to Flamsteed designations in the way that they number stars within a constellation in increasing order of right ascension. Each star is assigned an integer (starting at 1), followed by " G. " (or occasionall ...
*
Lists of constellations
The following lists of constellations are available:
* IAU designated constellations – a list of the current, or "modern", constellations
* Former constellations – a list of former constellations
* Chinese constellations – traditional Chines ...
*
Star catalogue
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 year ...
*
Stellar designations and names
In astronomy, stars have a variety of different stellar designations and names, including Star catalogue, catalogue designations, current and historical proper names, and foreign language names.
Only a tiny minority of known stars have named star ...
*
Table of stars with Bayer designations
*
Variable star designation
In astronomy, a variable-star designation is a unique identifier given to variable stars. It extends the Bayer designation format, with an identifying label (as described below) preceding the Latin genitive of the name of the constellation in whic ...
References
Notes
{{DEFAULTSORT:Bayer Designation
Astronomical catalogues
*