STAR NAMES
The naked-eye stars carry a huge number of names that range from
the intimately familiar to the hopelessly obscure, each one having
a different reason for being. Vega, the
fourth brightest star in the sky, has over 40 different names!
Star names are either of ancient origin, of more recent historical
origin, or are assigned by astronomical organizations under the
umbrella of the International Astronomical Union (the organization
of professional research astronomers). No private organizations
have the rights to name stars.
The best-known and most-familiar names are "popular names," real
names like those used for people. The oldest of all names, proper
names are a mixed lot that descend from a variety of ancient (and
even modern) languages that relate to the positions or the
characters of the stars. Among the oldest are those from ancient
Greek. Sirius, for example, means
"searing" or "scorching," appropriate for the brightest star in the
sky. Procyon comes from the Greek "pro
kion," before the dog," as from the northern hemisphere it rises
before the "Dog Star," Sirius; Castor
honors one of the ancient Greek warrior twins; Arcturus means "bear driver," as this
brilliant star follows the Greater Bear around the pole. A smaller
number (Regulus, the "little king" in
Leo), Polaris, the "pole star" in Ursa Minor) come from Latin.
By far the greatest number, however, hundreds of proper names,
descend to us from the Arabic of the middle ages, when the
astronomers of the Arabia adopted the Greek constellations from Ptolemy and applied their
own names to the stars, most in some way appropriate to the
locations of the stars within their parent constellations.
"Deneb," for example, means "tail." The name appears in many
forms, such as Deneb in Cygnus (the tail
of the Swan), Denebola in Leo (the
Lion's tail), and Deneb Kaitos in Cetus (the sea-monster's tail). Others
were derived from the constellations that the Arabs had made for
themselves.
When the Arabic texts were translated back into Latin, these star
names were passed down to us, but often in a highly corrupted form
that either changed the meaning, or in extreme cases left us with
no meaning at all. Other names were mistakenly transferred from
one star to another, so that a name might even refer to a different
constellation (Greek or Arabic) rather than to the one of the
star's actual residence.
To bring order out the chaos of proper names, around the year 1600
Johannes Bayer, in what is now Germany, applied lower case Greek letter names to the stars more or less
in order of brightness, which if followed strictly would render the
brightest star in a constellation "Alpha," the second Beta," and so
on. To the Greek letter name is appended the Latin possessive form of the constellation name.
Thus the brightest star in Lyra, Vega (an Arabic proper name),
becomes Alpha of Lyra or Alpha Lyrae (where "Lyrae" means "of
Lyra.") The brightness rule is commonly violated, however, as
Bayer also clearly factored in the position of the star within the
constellation, as in Ursa Major, where the
stars of the Big Dipper are lettered
west to east. As another good example, though Adhara in Canis
Major (the Greater Dog) is first magnitude and the second
brightest star in the constellation, it received "Epsilon,"
probably because of its lower (more southerly) position within the
starry figure.
With only 24 letters in the Greek alphabet, few stars could receive
Greek letter names. Bayer therefore followed the lower-case Greek
alphabet with upper case A and then lower-case Roman letters.
These are rarely used nowadays, however, and only a few vestiges
like "h Persei" (a star cluster in Perseus) survive. Though the number of names is
increased by applying numerical superscripts to stars that fall
near one another (a string of stars in Orion becoming Pi-1, Pi-2, Pi-3
Orionis, and so on, expressed as superscripts), the system was
still limited to the brighter stars, faint naked-eye stars rarely
qualifying. Others applied Greek and Roman letters to the later
modern constellations. The eighteenth century's Nicholas-Louis de
Lacaille was particularly notable for his work in the part of the
southern hemisphere that Bayer could not see.
To organize more of the naked eye stars, in the eighteenth century
John Flamsteed (who created one of the great star catalogues of the
time) listed the stars by position (right ascension, the sky's analogue
to terrestrial longitude) within the constellation boundaries.
Serial numbers applied by Edmund Halley then gave the star's
relative location from west to east within the constellation. For
example, 1 Lyrae would be the western-most numbered star in Lyra,
2 Lyrae the next, and so on (Vega is 3 Lyrae). In general, first
magnitude (and a few special) stars are commonly known by their
proper names. Greek-letter names are then used until they run out,
and then the Flamsteed numbers. From England, Flamsteed could see
only so far into the southern hemisphere, so deep southern
constellations have no numbers. The handful of exceptions (30
Doradus in the Large Magellanic Cloud, the
globular cluster 47 Tucanae) are vestiges of other systems
that did not survive.
To include yet more stars, constellations are dropped and the stars
are named according to position, generally right ascension, or
angle to the east of the Vernal
Equinox. (The Vernal Equinox is the point in Pisces where the ecliptic, the path of the Sun, crosses
the celestial equator going north and
where we find the Sun on the first day of northern spring.)
Catalogues fall into two broad categories: general and special
interest. The most basic of the general variety is the "Bright
Star Catalogue," which serially numbers 9000 naked-eye stars
through sixth magnitude from west to east beginning at right
ascension zero hours (zero degrees) for the year 1900. (Precession, the 26,000-year wobble in
the Earth's axis, changes the right ascensions with time, usually
increasing them.) Though now published at Yale, it derives from a
catalogue produced at Harvard, so the star names take on the name
"HR" for "Harvard Revised." Vega = Alpha Lyrae = 3 Lyrae = HR
7001.
Stars below naked-eye visibility need catalogue names too. The
most famed general catalogue for fainter stars, the "Bonner
Durchmusterung" (the Bonn Survey), was compiled in Germany in the
nineteenth century and lists stars through around tenth magnitude
(some 50 times fainter than the eye can see alone). It divides the
sky into declination strips one
degree wide and then serially numbers the stars from west to east
according to the stars' right ascensions (for the year 1855).
(Declination is the sky's analogue to terrestrial latitude; it
gives the angular separation of a star from the celestial equator.)
The catalogue name incorporates the declination. Vega, for
example, is also "BD+38° 3238," which means the 3238th star in
the declination strip between 38 and 39 degrees north. The BD
covers stars to -2 degrees declination (2 degrees south of the
celestial equator). The rest of the southern hemisphere is covered
by the "Cordoba Durchmusterung" (the Cordoba, Argentina, Survey),
or CD. Canopus (HR 2326) is CD-
52°914, or the 914th listed star between declination 52 and 53
degrees south. BD and CD are sometimes combined as "DM" for
"Durchmusterung." Precession has now moved many stars out of their
original declination strips.
The most commonly used catalogue for fainter (as well as brighter)
stars is the Henry Draper (HD) Memorial Catalogue, which serially
numbers stars through roughly tenth magnitude to the east of the
vernal equinox (according to right ascension in the year 1900)
independently of declination. The HD catalogue, while a general
tool for star names, is also a specialty catalogue, and was created
to list the spectral classes of
over 300,000 stars. Vega is HD 172167, Canopus HD 45348.
In the 1960s over ten positional catalogues were combined into the
Smithsonian Astrophysical Observatory (SAO) star catalogue. It
serially numbers over 250,000 stars (according to right ascensions
for the year 1900) to ninth magnitude in 10 degree declination
strips from north to south, each strip picking up where the last
one left off. Vega is SAO 067174, Canopus SAO 234480. Though it
enjoyed some popularity, it is no longer commonly in much
use.
The specialty Hipparcos Catalogue is also of general use. The
Hipparcos satellite was flown in the 1990s to measure precise distances (through accurate
parallaxes) to nearby stars. Over 100,000 stars are listed. Vega
is HIC 91262, Canopus HIC 30438.
Beyond these and many other catalogues, fainter stars are named
only by coordinates (right ascension and declination) for a
specific year. The Hubble Space Telescope Guide Star Catalogue,
for example, lists 19 million stars between 6th and 16th magnitude.
A huge number of stars are double or multiple, the
individuals locked in orbit around each other. The components of
very wide doubles that have Greek letter names are often
distinguished by applying superscripts to the Greek letters from
east to west (as noted in the earlier section on Greek letter
names). Zubenelgenubi, Alpha
Librae, is a wide double; the western of the two is Alpha-1, the
eastern Alpha-2, even though Alpha-2 is much the brighter. Most of
these are not physical doubles but line of sight
coincidences.
When the stars are close to each other, a system of Roman letters
generally applied in order of discovery or of descending brightness
(often the same thing) is used. The principal component is "A,"
the next brightest "B," and so on. Brilliant Sirius is accompanied by a faint white dwarf. The naked-eye
star is Sirius A, the dim companion Sirius B. Close companions,
particularly planets, are often given lower case letters. If a planet were to be discovered orbiting Sirius A
(there is none so far as we know), it would be Sirius Ab, rendering
Sirius itself Sirius Aa.
A great many stars are variable in brightness. The first found,
among them Mira and Algol, were bright and had proper or Greek
letter names. But as more were discovered, astronomers needed a
systematic naming system. Since the last Roman letter in any
constellation was "Q," they adopted "R" for the first variable
found that did not already have a name, to which was appended the
Latin possessive of the constellation name. The first such
variable known in Cygnus is thus R Cygni, the first in Aquila R
Aquilae. The sequence continued with new discoveries to Z.
Finding more, astronomers went back up the alphabet to use double
letters, beginning with RR, then going to RS, RT...RZ, then to SS,
ST...SZ, TT, TU...and finally down to ZZ.
To accommodate increasing numbers, the system then went to the top
of the alphabet, to AA, AB...AZ, BB, BC...BZ, CC...and so on to
QQ...QZ, with J left out to avoid confusion. After 334 letter
combinations, astronomers just gave up and used "V" followed by a
number, V335 Sagittarii following QZ Sagittarii.
Through the names, the astronomers of the past 3000 years have
brought order to the seeming chaos of the sky. All the stars you
can see even through a relatively large telescope have names. We
know them and know where they are.
Copyright © James B. Kaler. All rights reserved. These
contents are the property of the author and may not be reproduced
in whole or in part without the author's express consent except in
fair use for educational purposes. This page was last modified on
14 February, 2014.
Thanks to reader number 
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