The Caldwell Objects

103
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Tarantula Nebula;
True Lover’s Knot
NGC 2070
Type: Emission Nebula
and Star Cluster
Con: Dorado
RA: 05 h 38.6 m
Dec: -69° 05'
Mag: ~4.0 (O'Meara; neb-
ula)
Dim: 30' x 20' (nebula)
Mag: 8.3 (cluster)
Diam: 5' (cluster)
Dist:~170,000 light-years
Disc: Abbe Nicolas Louis
de Lacaille, included in his
1755 catalog
J. HERSCHEL: An assemblage of loops.
[Extensive notes follow.] (h2941)
A LITTLE MORE THAN 60° DUE SOUTH OF THE
Orion Nebula — considered by many to be the
heavens' reigning showpiece — lies an equally
remarkable southern treasure: NGC 2070 (Caldwell
103), the famous Tarantula Nebula and its
associated star cluster. Also known collectively as
30 Doradus, these objects appear to the naked eye
as a single irregular glow just north of the eastern
tip of the Large Magellanic Cloud's central bar.
The Tarantula is the brightest of the 50 or more
nebulae populating that neighboring galaxy, and
it punctuates the system's visual grandeur.
The Tarantula Nebula is an extraordinarily
massive and luminous Η II region — a large
concentration of (mostly) hydrogen gas ionized
by ultraviolet radiation from very hot, luminous
stars embedded within it. Indeed, as seen from
Earth today, thousands of suns are
GC / NGC: A magnificent object, very bright, very large,
looped.
being born within this gaseous cocoon. With
800,000 Suns' worth of ionized hydrogen, the
Tarantula is not only the brightest Η II region in
the LMC; it is also the most massive Η II region
known in the Local Group of galaxies. The
nebula is truly enormous, spanning about 3,000
light-years; by comparison, the Orion Nebula
stretches across a mere 40 light-years of space.
The Tarantula's bright inner nebulosity — the
part of the nebula most commonly detected by
eye — spans about 1,500 light-years, and it
contains at its core the star cluster responsible for
ionizing the entire nebula. The cluster measures
about 250 light-years across.
Astronomers have shown that the Tarantula
contains a spectacularly high number of blue
supergiants, many of which are of spectral type
O3 (the most massive stars known, each about
100 times as massive as our Sun).
The Caldwell Objects 405