Emission nebula | |
---|---|
H II region | |
Observation data: J2000 epoch | |
Right ascension | 17h 24m [1] |
Declination | −34° 20′ [1] |
Distance | ~5900±450 [2] ly (1800±140 pc) |
Constellation | Scorpius [3] |
Designations | War and Peace Nebula, [1] Lobster Nebula [4] Sharpless 11, RCW 131, Gum 66, Madokami |
NGC 6357 is a diffuse nebula near NGC 6334 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. [4] [5] This nebula was given the name War and Peace Nebula 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. [6] A petition by anime fans to rename it as the Madokami nebula, due to resemblance with a character, was unsuccessful. [7] [8]
It is located about ~5,500 light years away from Earth. [9]
This nebula includes the open cluster Pismis 24, which is home to several massive stars. One of the brightest stars in the cluster, Pismis 24-1, was thought possibly to be the most massive on record, approaching 300 solar masses, until it was discovered to be a multiple system of at least three stars; component stars would still remain near 100 solar masses each, making them among the more massive stars on record. [10] [11]
The young stellar cluster G353.2+0.7 lies east of Pismis 24 and was revealed by a Chandra X-ray image showing approximately 800 stars. [12]
The young stellar cluster G353.1+0.6 lies southeast of Pismis 24 and also contains approximately 800 stars detected by X-ray. [12] The region includes several O-type stars, including [BDSB2003] 10. [13]
NGC 6357 is one of the most prominent sites of massive-star formation in our neighborhood of the Milky Way. A variety of early O-type stars reside in this nebula, blowing the bubbles around the star clusters that can be seen in the molecular cloud.
Star name | Spectral type | Magnitude (Mbol) | Temperature [15] (K) | Radius (R☉) | Mass (M☉) |
---|---|---|---|---|---|
WR 93 (HD 157504) | WC7 | -11.2 | 71,000 | 10 | 120 |
Pismis 24-1NE | O3.5 If* | −10.0 | 42,000 | 17 | 74 |
Pismis 24-1SW | O4 III | −9.8 | 41,500 | 16 | 66 |
Pismis 24-2 | O5.5 V(f) | −8.9 | 40,000 | 12 | 43 |
Pismis 24-3 | O8 V | −7.7 | 33,400 | 9 | 25 |
Pismis 24-10 | O9 V | −7.2 | 31,500 | 8 | 20 |
Pismis 24-12 | B1 V | −5.3 | 30,000 | 4 | 11 |
Pismis 24-13 | O6.5 III((f)) | −8.6 | 35,600 | 12 | 35 |
Pismis 24-15 | O8 V | −7.8 | 33,400 | 10 | 25 |
Pismis 24-16 | O7.5 V | −9.0 | 34,000 | 16 | 38 |
Pismis 24-17 | O3.5 III | −10.1 | 42,700 | 17 | 78 |
Pismis 24-18 | B0.5 V | −6.4 | 30,000 | 6 | 15 |
Pismis 24-19 | B0.5 V | −5.4 | 30,000 | 4 | 11 |
The Trifid Nebula is an H II region in the north-west of Sagittarius in a star-forming region in the Milky Way's Scutum-Centaurus Arm. It was discovered by Charles Messier on June 5, 1764. Its name means 'three-lobe'. The object is an unusual combination of an open cluster of stars, an emission nebula, a reflection nebula, and a dark nebula. Viewed through a small telescope, the Trifid Nebula is a bright and peculiar object, and is thus a perennial favorite of amateur astronomers.
The Tarantula Nebula is a large H II region in the Large Magellanic Cloud (LMC), forming its south-east corner.
The Eagle Nebula is a young open cluster of stars in the constellation Serpens, discovered by Jean-Philippe de Cheseaux in 1745–46. Both the "Eagle" and the "Star Queen" refer to visual impressions of the dark silhouette near the center of the nebula, an area made famous as the "Pillars of Creation" imaged by the Hubble Space Telescope. The nebula contains several active star-forming gas and dust regions, including the aforementioned Pillars of Creation. The Eagle Nebula lies in the Sagittarius Arm of the Milky Way.
Photoevaporation denotes the process where energetic radiation ionises gas and causes it to disperse away from the ionising source. This typically refers to an astrophysical context where ultraviolet radiation from hot stars acts on clouds of material such as molecular clouds, protoplanetary disks, or planetary atmospheres.
The Carina Nebula or Eta Carinae Nebula is a large, complex area of bright and dark nebulosity in the constellation Carina, located in the Carina–Sagittarius Arm of the Milky Way galaxy. The nebula is approximately 8,500 light-years (2,600 pc) from Earth.
NGC 3603 is a nebula situated in the Carina–Sagittarius Arm of the Milky Way around 20,000 light-years away from the Solar System. It is a massive H II region containing a very compact open cluster HD 97950.
R Monocerotis, abbreviated R Mon, is a very young binary star system in the equatorial constellation of Monoceros. The apparent magnitude of R Mon varies between 10 and 12 and the spectral type is B8IIIe.
The Flame Nebula, designated as NGC 2024 and Sh2-277, is an emission nebula in the constellation Orion. It is about 900 to 1,500 light-years away.
R136 is the central concentration of stars in the NGC 2070 star cluster, which lies at the centre of the Tarantula Nebula in the Large Magellanic Cloud. When originally named it was an unresolved stellar object but is now known to include 72 class O and Wolf–Rayet stars within 5 parsecs of the centre of the cluster. The extreme number and concentration of young massive stars in this part of the LMC qualifies it as a starburst region.
Pismis 24-1, also known as HD 319718, is the brightest star of the open cluster Pismis 24 within the nebula NGC 6357 about 6,500 light-years away. It was once thought to be the most massive star known, but is composed of at least three individual objects, each still among the most luminous and most massive stars known.
NGC 346 is a young open cluster of stars with associated nebula located in the Small Magellanic Cloud (SMC) that appears in the southern constellation of Tucana. It was discovered August 1, 1826 by Scottish astronomer James Dunlop. J. L. E. Dreyer described it as, "bright, large, very irregular figure, much brighter middle similar to double star, mottled but not resolved". On the outskirts of the cluster is the multiple star system HD 5980, one of the brightest stars in the SMC.
NGC 6334, colloquially known as the Cat's Paw Nebula, Bear Claw Nebula, or Gum 64, is an emission nebula and star-forming region located in the constellation Scorpius. NGC 6334 was discovered by astronomer John Herschel in 1837, who observed it from the Cape of Good Hope in South Africa. The nebula is located in the Carina–Sagittarius Arm of the Milky Way, at a distance of approximately 5.5 kilolight-years from the Sun.
NGC 1333 is a reflection nebula located in the northern constellation Perseus, positioned next to the southern constellation border with Taurus and Aries. It was first discovered by German astronomer Eduard Schönfeld in 1855. The nebula is visible as a hazy patch in a small telescope, while a larger aperture will show a pair of dark nebulae designated Barnard 1 and Barnard 2. It is associated with a dark cloud L1450. Estimates of the distance to this nebula range from 980–1,140 ly (300–350 pc).
NGC 6530 is a young open cluster of stars in the southern constellation of Sagittarius, located some 4,300 light years from the Sun. It exists within the H II region known as the Lagoon Nebula, or Messier 8, and spans an angular diameter of 14.0′. The nebulosity was first discovered by G. B. Hodierna prior to 1654, then re-discovered by J. Flamsteed circa 1680. It was P. Loys who classified it as a cluster in 1746, as he could only resolve stars. The following year, G. Le Gentil determined it was both a nebula and a cluster.
IC 5146 is a reflection/emission nebula and Caldwell object in the constellation Cygnus. The NGC description refers to IC 5146 as a cluster of 9.5 mag stars involved in a bright and dark nebula. The cluster is also known as Collinder 470. It shines at magnitude +10.0/+9.3/+7.2. Its celestial coordinates are RA 21h 53.5m, dec +47° 16′. It is located near the naked-eye star Pi Cygni, the open cluster NGC 7209 in Lacerta, and the bright open cluster M39. The cluster is about 4,000 ly away, and the central star that lights it formed about 100,000 years ago; the nebula is about 12 arcmins across, which is equivalent to a span of 15 light years.
NGC 2060 is a star cluster within the Tarantula Nebula in the Large Magellanic Cloud, very close to the larger NGC 2070 cluster containing R136. It was discovered by John Herschel in 1836. It is a loose cluster approximately 10 million years old, within one of the Tarantula Nebula's superbubbles formed by the combined stellar winds of the cluster or by old supernovae.
NGC 6193 is open cluster containing 27 stars in the constellation Ara, visible to the unaided eye. NGC 6193 lies at the center of the Ara OB1 association, which extends over a square degree. The cluster is associated with neighboring regions of the nebulosity NGC 6188.
Westerlund 1-75 or Wd 1-75 is a red supergiant (RSG) located in the Westerlund 1 super star cluster. Its radius is calculated to be around 668 solar radii (4.65 × 108 km, 3.10 au). This corresponds to a volume 298 million times bigger than the Sun. If placed at the center of the Solar System, Westerlund 1-75 would engulf the inner limits of the asteroid belt.