|Designation|| Cadwell 49|
NGC 2244 (cluster)
|Right ascension||06h 33m 45s|
|Declination||+04° 59′ 54″|
|Type of object||Emission nebula|
|Magnitude|| Apparent Mag: +9|
Absolute Mag: -2
|Distance from Earth||5,200 ly|
|Radial velocity||26.16±3.37 km/s|
|Proper motion|| RA: -1.45 mas/yr|
The Rosette nebula (Cadwell 49) is an emission nebula in the constellation of Monoceros. The nebula comprises mainly of a large gas cloud and an associated open star cluster, designated NGC 2244, but smaller clusters are also present. The nebula's similar appearance to a rose has earned it the name Rosette (sometimes Rosetta) nebula. However, from a different angle it resembles a skull, leading to some also calling it the "Skull nebula." The open cluster can be see using binoculars but the nebula surrounding it requires a telescope to observe it.
The nebula and its contents were not discovered by a single person, due it the difficulty in its observation. The bright star cluster, NGC 2244 was the first to be observed by John Flamstead in 1690. John Herschel discovered the main open cluster, NGC 2239, at the centre of the nebula in 1784. NGC 2237 and NGC 2246 were both discovered by Lewis Swift and NGC 2238 was first observed by Albert Marth.
Properties and Structure
The nebula consists of a large cloud of gas and dust along with several star cluster: NGC 2237, NGC 2238, NGC 2239, NGC 2244 and NGC 2246. NGC 2244 corresponds to the bright open star cluster in the centre of the nebula. It is difficult to determine exactly what the others correspond to as they were identified before astronomers realised there was only one single nebula.
The Rosette nebula is 130 light years across, meaning it is three times larger than the Orion nebula and appears about five times larger than a full Moon on the night sky. With a mass of 10,000 solar masses, it is one of the largest emission nebulae known. On zoomed in photographs of the nebula, dust lanes are also visible
NGC 2244 is a bright open cluster situated in the heart of the Rosette nebula. With an apparent magnitude of 4.8, the stars are sufficiently bright to be seen with the naked eye. The brightest stars in the cluster belong to the stellar classification O4V, a rare class of blue stars, significantly brighter and more massive than the Sun. These stars are output around 400,000 times more energy than the sun/ The vast amount of radiation these stars output produce very strong stellar winds. This blows gas away from the stars and is responsible for there being a lack of gas in the central regions of the nebula. In images taken by NASA's Spitzer Space Telescope, spheres of dust can be seen surrounding these hot stars.
- Rosette nebula from constellation-guide.com
- From definition of absolute magnitude, using apparent magnitude and distance given here.
- NGC 2244 from simbad.u-strasbg.fr
- NGC 2237, 2238, 2239 and 2246 - The Rosette Nebula from atlasoftheuniverse.com