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, rendering 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 more
often violated than not, however, as Bayer also factored in the
position of the star within the constellation. 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 lower-case Roman letters, then with upper case Roman
letters. These are rarely used nowadays, however, and only a few
vestiges like "h Persei" (actually a star cluster in Perseus) and
G Scorpii survive. Though the number of names is increased by
applying superscripts to stars that fall near one another (a string
of stars in Orion became Pi-1, Pi-2, Pi-
3 Orionis, and so on), the system was still limited to the brighter
stars, faint naked-eye stars never qualifying.
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 later then gave the star's
relative location from west to east within the constellation. For
example, 1 Lyrae would be the western-most 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.
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 is 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. 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.
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.
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 Bayer's 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 is 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 give up and just 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 © 2000. 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 7 January, 2000.
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