Monoceros OB1
| Emission nebula | |
|---|---|
| H II region | |
| Observation data: J2000 epoch | |
| Right ascension | 06h 34m 60s[1] |
| Declination | +10° 05′ 60″[1] |
| Distance | ~2,350 to ~2,600[2] ly |
| Constellation | Monoceros |
| Designations | [WAM91] Monoceros I, Monoceros I, Monoceros OB1 Molecular Cloud, Monoceros I Association[1] |
Monoceros OB1 (or the Monoceros OB1 Molecular Cloud for the giant molecular cloud) is an active star-forming region and giant molecular cloud (GMC) approximately 2,350 to 2,600 light-years (or 720 to 800 parsecs) away in the constellation Monoceros, toward the galactic anticenter direction.[2][3]
Observations
[edit]
Monoceros OB1 region is located in northwestern Monoceros and is centered around NGC 2264. Most of the Monoceros OB1 region is visible through amateur telescopes, including the Cone Nebula and IC 447 while the huge cloud around NGC 2264 is visible through H-alpha (Hα) filters. The farthest component is Monoceros R1 at 800 pc while the closest component is NGC 2264 at 720 pc.[2][3]
Structure
[edit]NGC 2264
[edit]NGC 2264 is an open cluster and H II region that forms the center of the Monoceros OB1 region. The Cone Nebula, the Fox Fur Nebula, the Christmas Tree Cluster, and the Snowflake Cluster are located within NGC 2264. The region is enriched with hydrogen and helium that fuel the formation of new luminous stars.[4][5]
Monoceros R1 Molecular Cloud
[edit]The Monoceros R1 Molecular Cloud is a stellar association and molecular cloud adjacent to NGC 2264. Monoceros R1 is rich in B-type stars and T Tauri stars, with most of these stars located within the core designated as IC 447. The open cluster Collinder 95 created IC 447 via supernovae.[3] Monoceros R1 has a ring like structure that created the most of complex through shock-induced heating. The reflection nebulae associated with Monoceros R1 are IC 447, IC 446, VdB 76, VdB 77, NGC 2247, and NGC 2245.[6]
G202.3+2.5
[edit]The filament designated as G202.3+2.5 is a complex star-forming cloud located at the edge of the Monoceros OB1 region. This filament is composed of a background northern filament and a foreground main filament. These two components are moving towards each other, the tip of the northern filament is collided approximately one hundred thousand years ago. The filament is rich in protostars, which are found mostly in the colliding region while the rest of the filament has little to no star formation.[7]
East Cloud
[edit]The east cloud of the region has a greater influence on the dynamics of the southern region than in the northern region. The filaments in the and the diffuse inflow in the southern part are perpendicular to the magnetic field of the east cloud. The northern region is stabilized by the magnetic field and turbulence of the east cloud at scales larger than a parsec.[8]
Other Objects
[edit]Herbig–Haro objects HH 225 and HH 226 may be connected to HH 125.[9] These Herbig–Haro object|Herbig–Haro objects along with HH 575 and HH 572 which have an uknown source, are not associated with any major carbon monoxide (CO) outflow.[10] The CO outflows and Herbig–Haro objects form very differently, the Herbig–Haro objects are mostly concentrated in the middle of the cloud while the CO outflows are evenly distributed. This shows that the Monoceros OB1 region had a experienced enhanced star formation activity somewhere earlier in its life and primarily occurred in the middle of the region where NGC 2264 is located.[11] The discovery of nine molecular outflows that have luminosities greater than LDN 1551 proves that the solar neighborhood within 1 kpc from the Sun is more abundant in molecular outflows than previously thought.[12]
Star formation
[edit]Monoceros OB1 Association
[edit]Most star formation occurs in the Monoceros OB1 association, which is an OB association. The stars in the Monoceros OB1 region are mostly O-type and B-type stars that ionize a vast Hα halo spanning roughly 1.5° in radius. Star formation has been sustained for about 2 to 5 million years with most star formation concentrated in the southern region. Monoceros R1 has different star formation characteristics compared to Monoceros OB1, this is because Monoceros R1 produces only intermediate or low-mass stars rather than high-mass stars like the rest of the association. The S Monocerotis moving group is mainly comprised of pre main sequence stars and O and B-type stars, these stars are formed the Hα halo around NGC 2264 and the Fox Fur Nebula through supernovae.[3][13][10]
References
[edit]- 1 2 3 "NAME Mon I". simbad.cds.unistra.fr.
- 1 2 3 Sharma, Vikalp; Vig, Sarita; Patel, Vishwas (January 2024). "Gaia view of star forming region Monoceros Ob1 and its nearby young clusters". 42nd Meeting of the Astronomical Society of India (ASI). Bibcode:2024asi..confP.171S. P171.
- 1 2 3 4 Lim, Beomdu; Nazé, Yaël; Hong, Jongsuk; Yoon, Sung-yong; Lee, Jinhee; Hwang, Narae; Park, Byeong-Gon; Lee, Jeong-Eun (June 2022). "A Gaia View on the Star Formation in the Monoceros OB1 and R1 Associations". The Astronomical Journal. 163 (6): 266. arXiv:2204.00444. Bibcode:2022AJ....163..266L. doi:10.3847/1538-3881/ac63b6.
- ↑ Pearson, Samuel; Scholz, Aleks; Teixeira, Paula S.; Mužić, Koraljka; Almendros-Abad, Víctor (2021). "The first spectroscopically confirmed brown dwarfs in NGC 2264". Monthly Notices of the Royal Astronomical Society. 507 (3): 4074–4085. arXiv:2108.07633. doi:10.1093/mnras/stab2394. hdl:10023/24020.
- ↑ Sagar, R.; Joshi, U. C. (November 1983). "Study of the open cluster NGC 2264". Monthly Notices of the Royal Astronomical Society. 205 (3): 747–758. Bibcode:1983MNRAS.205..747S. doi:10.1093/mnras/205.3.747.
- ↑ Kutner, M. L.; Dickman, R. L.; Tucker, K. D.; Machnik, D. E. (September 1979). "Ring structure in the Monoceros R1 molecular clouds". Astrophysical Journal. 232 (1): 724–728. Bibcode:1979ApJ...232..724K. doi:10.1086/157332.
- ↑ Bőgner, R.; Montillaud, J.; Vastel, C.; Juvela, M.; Tóth, L. V. (December 2024). "Multi-scale analysis of the Monoceros OB 1 star-forming region". Astronomy and Astrophysics. 631: L1. arXiv:1909.03781. Bibcode:2019A&A...631L...1M. doi:10.1051/0004-6361/201936377.
- ↑ Alina, D.; Montillaud, J.; Hu, Y.; Lazarian, A.; Ristorcelli, I.; Abdikamalov, E.; Sagynbayeva, S.; Juvela, M.; Liu, T.; Carrière, J.-S. (February 2022). "Large-scale magnetic field in the Monoceros OB 1 east molecular cloud". Astronomy and Astrophysics. 658: A90. arXiv:2007.15344. Bibcode:2022A&A...658A..90A. doi:10.1051/0004-6361/202039065. A90.
- ↑ Walsh, J. R.; Ogura, K.; Reipurth, Bo (July 1992). "Two remarkable Herbig–Haro objects in the NGC 2264 region". Monthly Notices of the Royal Astronomical Society. 257 (1): 110–118. doi:10.1093/mnras/257.1.110.
- 1 2 Ogura, K. (March 1984). "New Hα-Emission Stars in Monoceros OB1 and R1 Associations". Publications of the Astronomical Society of Japan. 36 (1): 139–148. Bibcode:1984PASJ...36..139O. doi:10.1093/pasj/36.1.139.
- ↑ Wang, Hongchi; Yang, Ji; Wang, Min; Yan, Jun (February 2003). "Herbig-Haro Objects in the Monoceros OB1 Molecular Cloud". The Astrophysical Journal. 125 (2): 842–849. Bibcode:2003AJ....125..842W. doi:10.1086/345887.
- ↑ Margulis, Michael; Lada, Charles J.; Snell, Ronald L. (October 1988). "MOLECULAR OUTFLOWS IN THE MONOCEROS OBI MOLECULAR CLOUD". The Astrophysical Journal. 333: 316–331. Bibcode:1988ApJ...333..316M. doi:10.1086/166748.
- ↑ Lim, Beomdu; Naze, Yael; Hong, Jongsuk; Yoon, Sungyong; Lee, Jinhee; Hwang, Narae; Park, Byeong-Gon; Lee, Jeong-Eun (2021). "A kinematic study of young stars in Monoceros OB1 and R1 associations". The Bulletin of the Korean Astronomical Society. 46 (2): 1–50. Bibcode:2021BKAS...46R..50L.
