Lobster Nebula - NGC 6357

NGC 6357 is a diffuse emission nebula near NGC 6334 (Cat’s Paw Nebula) in the constellation Scorpius. The nebula contains many proto-stars shielded by dark discs of gas, and young stars wrapped in expanding "cocoons" or expanding gases surrounding these small stars. It is also known as the Lobster Nebula or War and Peace Nebula, the latter given by the Midcourse Space Experiment scientists because of its appearance, which, in infrared images the bright, western part resembles a dove, while the eastern part looks like a skull.

The nebula was discovered by John Herschel on 8 June 1837, when he was in South Africa exploring the southern sky with his homemade 18¼ inch reflecting telescope. He catalogued the nebula as h 3682 and noted: «Faint, large, extended, very gradually little brighter in the middle, milky nebulosity, 2' long, 1 1/2' broad, close to and almost involves a double star.» Dreyer then adopted the nebula including the description in 1888 as NGC 6357 in his «New General Catalogue».

The powerful stellar winds created the numerous erosion patches within the nebula, where the star clusters are visible. Huge filaments of gas and dust are also in a permanent change as the stars form and migrate inside the nebula.

The nebula is located about 5.500 light years away from Earth. NGC 6357 is connected by a filamentary structure to NGC 6334, and the two may form a single complex. Lobster Nebula is associated with several star clusters, most of them made of very massive and bright stars:

- Pismis 24 – this cluster sits in the middle of the nebula, and among others, it contains a triple star system where each of the members weighs a staggering ~100 solar masses each. Very close to Pismis 14 but unrelated to it, we can find a massive star, WR 93, with an estimated mass of 120 solar masses and 10 time the solar radius

- G353.2+0.7 – this cluster was discovered by Chandra X-Ray Observatory and it has approximately 800 stars

- G353.1+0.6 – very similar to G353+0.7, discovered also by Chandra