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Lobster Nebula

War and Peace Nebula, Gum 66, NGC 6357
Contains an open cluster sometimes also designated NGC 6357

Proper NamesLobster Nebula, War and Peace Nebula
Messier NumberNone
NGC/IC NumberNGC 6357
Other DesignationsGum 66
Right Ascension17h 26m 30s
Declination-34° 12' 0"
Distancec.8,000 light years
c.2,500 parsecs
MagnitudeApparent: +10.00
Absolute: -2.00
DimensionsApparent: 50' x 40'
Actual: 120 x 90 light years
Optimum VisibilityJune / July

A wide nebula that lies within the central parts of the Milky Way as it passes through northern Scorpius, which places it in the general direction of the Galaxy's core. The gases of the nebula are divided into two tapering branches, a western and an eastern, whose similarity to a lobster's claws give the nebula its common name. Seen in infrared, patterns within these arms seem to form the rough shapes of a dove and of a skull, hence the nebula's alternative name of the War and Peace Nebula.

Imagery provided by Aladin sky atlas

The distance to the Lobster Nebula is not known with precision, and estimates vary from about 5,500 light years out to some 9,000 light years. Seen from Earth, the nebula covers an area of the sky some fifty arcminutes across (that is, nearly twice the diameter of the Moon's disc). Depending on the nebula's exact distance, this suggests that the entire structure covers a region approximately one hundred light years across (note that the dimensions and absolute magnitude shown above are based on an estimated distance of 8,000 light years, and will necessarily vary for other distance values).

The Lobster Nebula is an important and active star-forming region. Contained within it are hundreds of stars emerging from the surrounding gas and dust, at different stages of evolution. Many of these stars lie within three significant open clusters, formed from within the nebula istelf, and each composed of several hundred hot young stars. Most notable among these is a cluster designated Pismis 24 in the shining heart of the nebula, which contains some of the most massive stars known, with some of these stars exceeding seventy times the mass of the Sun.


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