The Caldwell Objects

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Southern Ring; Eight-Burst Nebula
NGC 3132
Type: Planetary Nebula
Con: Vela
RA: 10 h 07 m 01.8 s
Dec: -40° 26' 12"
Mag: 9.4; 9.2 (O'Meara)
Dim: 84" x 53"
Dist:~2,000 light-years
Disc: John Herschel, 1835
J. H ERSCHEL: [Observed2 March 1835] Planetary nebula, very
large, very bright, elliptic; has in it a 9th magnitude] star
somewhat excentric. Its light is exactly equable, ie. not
increasing towards the middle; yet I cannot help imagining it to
be closely dotted. It is just like a star out of focus in certain
states of the mirror and atmosphere. Three stars near, a = 9th
magnitude]; b = 9th magnitude]; c = 14th
NGC 3132 is ONE OF THE MOST FANTASTIC
planetary nebulae accessible to small telescopes.
In shape, size, and brightness it is comparable to
M57, the Ring Nebula in Lyra, and for that reason
it is commonly called the Southern Ring. The
main difference between the two objects lies with
the brightnesses of their respective central stars:
NGC 3132's shines at 10th magnitude, while
M57's glimmers around 14th. In truth the 10thmagnitude,
type-A2 central star in NGC 3132 is
not hot enough to saturate the surrounding gases
with ultraviolet radiation and make them
fluoresce — not without help from a companion,
that is. This companion was discovered by Lubos
Kohoutek and Svend Laustsen with the 3.6-meter
telescope at the European Southern Observatory
in Chile. The 16th-magnitude star was found
1.65" away from its brighter partner at a position
angle of 226.3°. This dim partner has an earlier
spectral
292
magnitude]; A very extraordinary object, (h 3228)
GC / NGC: Remarkable, planetary nebula, very bright, very
large, little extended with a star of magnitude 9 in the middle,
4" diameter.
type than its l0th-magnitude companion, and it
exhibits an unusually high surface temperature,
possibly 100,000° Kelvin. It also lies more directly
along the nebula's symmetry axis, so it, and not
the 10th-magnitude star, is without question the
hot, ionizing dwarf star that blew off the
surrounding gas shell. A Hubble Space Telescope
image of the nebula clearly shows the two stars
near the center of the nebula. The two central
stars probably form a true binary pair, and their
mutual orbit would explain the nebula's wide
and "wobbly" ellipsoidal structure. In the future
the brighter star, which is in an earlier
evolutionary stage, will probably eject its own
planetary nebula, adding more drama to this
already glorious spectacle.
In detailed ground-based photographs, the
Southern Ring looks like a rosette of overlapping
ellipses, each skewed at a slightly different angle.
This appearance has led to its
The Deep Sky Companions: The Caldwell Objects