Rosette Nebula (NGC 2239)

The Rosette Nebula is a giant emission nebula located near one of the large molecular clouds in the constellation Monoceros of the Milky Way galaxy. It is a region of ionized hydrogen where active star formation processes occur. The nebula is located at a distance of about 5,200 light years from the Sun.

Nebula Center: Cluster NGC 2244

At the center of the Rosette Nebula is the NGC 2244 cluster, a young and bright cluster that is responsible for the formation of the hole in the center of the nebula. These stars heat the surrounding gas to temperatures of about 6,000 K, causing it to emit in X-rays. Their powerful radiation and stellar winds blow matter out of the center of the nebula. It is believed that the stellar wind causes globules of dust and gas to form, which slowly collapse under the influence of powerful radiation and wind. If these globules are left in the molecular cloud for a long time, stars and planets may begin to form in them.

NGC 2244 Cluster: Description

The NGC 2244 cluster is also known as the Cadwell Cluster 50 or the Satellite Cluster. It is an open star cluster in the Rosette Nebula, located in the constellation Monoceros. This cluster contains several O stars, super-hot stars that generate enormous amounts of radiation and stellar winds.

The cluster is estimated to be less than 5 million years old. The brightest star in the direction of the cluster is 12 Monocerotis, a foreground K-type giant. However, the two brightest stars in the cluster, HD 46223 (spectral type O4V) and HD 46150 (spectral type O5V), are significantly more luminous and massive. With masses up to 60 times greater than the Sun, these stars shine hundreds of thousands of times brighter than our Sun.

Stars and Protostars in NGC 2244

A 2023 study showed that the brown dwarfs in NGC 2244 form closer to OB stars than to other types of stars. This may be due to photoevaporation of the outer layers of protostellar cores, which would otherwise form lower-mass stars. It was also found that for objects with masses below K0, the fraction of objects with disks was only 39±9%. One member of the cluster showed signs of a collapsing disk, reminiscent of proplyds.

The Rosette Nebula and its Influence

The Rosette Nebula (also known as Caldwell 49) is an H II region near one end of a giant molecular cloud in the Milky Way. It is an emission nebula, and its stars formed from matter within the nebula.

The nebula's shape resembles a human skull, so it is sometimes called the Cranial Nebula. It should not be confused with NGC 246, also known as the Cranial Nebula.

Importance of the Research

A survey of the nebula using the Chandra X-ray Observatory has revealed hundreds of young stars in the nebula and molecular cloud. In total, this star-forming complex contains about 2,500 young stars, including the massive O-type stars HD 46223 and HD 46150, which are primarily responsible for forming the ionized bubble in the nebula.

There is also diffuse X-ray emission between the stars in the bubble, which is explained by a super-hot plasma state with temperatures between 1 and 10 million K. This is significantly hotter than the plasma in the HII region, where the temperature does not exceed 10,000 K.

Conclusion

On April 16, 2019, the Oklahoma State Legislature passed HB1292, declaring the Rosette Nebula an official state astronomical feature. The bill was signed into law by Governor Kevin Sitt on April 22, 2019.