Download Star Names and Catalogs

2-1
Looking Deeper into Astronomy
Star Names and Catalogs
T
he customs for naming stars have changed over the
centuries. Many of the brightest stars in the sky have
Arabic names that were assigned in medieval times,
when astronomy was widely studied among Islamic nations.
The illustration shows the Big Dipper with the Arabic names
for its seven brightest stars. The North Star received its
formal name, Polaris, later, when Latin was the language
used by European astronomers.
Polaris
␨ Mizar
Alkaid
⑀
Alioth
␦
Phecda
Megrez
␥
␣
␤
Dubhe
Merak
As you might suspect, memorizing exotic star names is an
unwelcome burden for many astronomers. A simpler system,
invented by Johann Bayer in 1603, uses the constellation
names and the 24 lowercase letters of the Greek alphabet:
α
β
γ
δ
ε
ζ
η
θ
alpha
beta
gamma
delta
epsilon
zeta
eta
theta
i iota
κ kappa
λ lambda
µ mu
ν nu
ξ xi
ο omicron
π pi
ρ
σ
τ
υ
φ
χ
ψ
ω
rho
sigma
tau
upsilon
phi
chi
psi
omega
In constructing a star name, a Greek letter is used with
the Latin possessive form of the name of the constellation in
which the star is located. In most cases, the brightest star in the
constellation is α, the second brightest is β, the third is γ, and so
on. For example, the brightest star in Libra (the Scales) is called
α Librae, or α Lib for short. This name is more informative, if
less melodious, than its Arabic name, Zubenelgenubi (meaning
“scorpion’s southern claw”). The 12 constellations of the
zodiac with their Latin possessives are as follows:
Constellation
Possessive
Aries
Taurus
Gemini
Cancer
Leo
Virgo
Libra
Scorpius
Sagittarius
Capricornus
Aquarius
Pisces
Arietis
Tauri
Geminorum
Cancri
Leonis
Virginis
Librae
Scorpii
Sagittarii
Capricornii
Aquarii
Piscium
!
In Bayer’s system, only the brightest two dozen stars in a
constellation can be named. However, astronomers are often
interested in very faint stars, many of which are too dim to be
seen with the naked eye. Astronomers refer to these fainter
stars by using designations from standard star catalogs.
One of the first major star catalogs, Bonner Durchmusterung
(Bonn Comprehensive Survey), was produced in Germany in the
mid-1800s by F. W. Argelander of the Bonn Observatory. This
catalog lists the positions of 324,188 stars, each of which is
designated by a BD number. For example, the star BD+5° 1668
is a dim star in the constellation Monoceros (the Unicorn).
Another frequently used catalog is the Henry Draper Catalogue,
which was compiled in the United States between 1911
and 1915. (It is named after a physician and avid amateur
astronomer whose widow financed the project.) The
225,300 stars in this catalog are listed by their HD numbers.
For example, HD 87901 is α Leonis (also called Regulus),
the brightest star in Leo (the Lion).
The most extensive catalog of stars yet compiled is the
Hubble Space Telescope Guide Star Catalog. This is an
immense list of 15,169,873 stars, all too faint to be seen by the
naked eye, whose positions are used to help in pointing the
Hubble Space Telescope (see Figure 1-3 on page 4 of
Universe). Stars from this catalog have GSC numbers, such as
the star GSC 1234 1132 in the constellation Taurus. Unlike
other star catalogs, this one is only available in electronic form
(on two CD-ROMs); if it were to be printed, it would require
hundreds of thousands of pages.
There are many star catalogs, including some that list only
stars of specific types. As a result, a single star may have a
plethora of different names. For example, the bright star
Vega in the constellation Lyra is also known as α Lyrae,
BD +38° 3238, HD 172167, 3 Lyrae, HR 7001, GC 25466,
SAO 67174, and ADS 11510. In this book we use the Bayer
system in most cases and thus will refer to this star simply
as “Vega (α Lyrae).”
A number of unscrupulous commercial firms offer to
UTION
CA
name a star for you for a fee. The money that they charge
you for this “service” is real, but the star names are not;
none of these names are recognized by astronomers. If you
want to use astronomy to commemorate your name or the
name of a friend or relative, consider making a donation to
your local planetarium or science museum. The money will
be put to much better use!