Orion OB1 Association
File:Orion OB1 & 25 Ori Group.png
Orion OB1 Association
The Orion OB1 stellar association is the group of hot giant stars in a large cluster. They are spectral types O and B. There are thousands of lower-mass stars also in this group, and some protostars.
The association is part of the larger Orion Molecular Cloud Complex. It is the most closely studied OB association.[1]
The Orion OB1 association has these subgroups:[1][2]
- Orion OB1a - the group of stars northwest of the Orion Belt stars with an average age of about 12 million years. Within this group is a subgroup known as the 25 Orionis group.[3][4] They are near the star Bellatrix.
- Orion OB1b - the three bright stars ζ Ori (Alnitak), ε Ori (Alnilam), and δ Ori (Mintaka) which make up the asterism known as "Orion's Belt", and minor stars. This group has an average age of about eight million years and has three subgroups.[5][6]
- Orion OB1c - the stars in Orion's Sword: 42 Orionis, θ Orionis, and ι Orionis. These stars are about 3-6 million years old.
- Orion OB1d - the stars of the Orion Nebula and M43 (the youngest stars)
Signs of stellar debris disk have been found in the 1a and 1b subgroups. That is a circumstellar disk of dust and debris in orbit around a star.[7][8]
References
- ↑ 1.0 1.1 Brown A.G.A.; de Geus E.J.; de Zeeuw P.T. (1994). "The Orion OB1 association. 1: Stellar content". Astronomy and Astrophysics. 289 (1): 101–120. arXiv:astro-ph/9403051. Bibcode:1994A&A...289..101B. ISSN 0004-6361.
- ↑ Lua error in Module:Citation/CS1/Identifiers at line 630: attempt to index field 'known_free_doi_registrants_t' (a nil value).
- ↑ Lua error in Module:Citation/CS1/Identifiers at line 630: attempt to index field 'known_free_doi_registrants_t' (a nil value).
- ↑ Harper, Graham M.; Brown, Alexander; Guinan, Edward F. (2008). "A New VLA-Hipparcos distance to Betelgeuse and its implications". The Astronomical Journal. 135 (4): 1430–40. Bibcode:2008AJ....135.1430H. doi:10.1088/0004-6256/135/4/1430.
- ↑ Lua error in Module:Citation/CS1/Identifiers at line 630: attempt to index field 'known_free_doi_registrants_t' (a nil value).
- ↑ Lua error in Module:Citation/CS1/Identifiers at line 630: attempt to index field 'known_free_doi_registrants_t' (a nil value).
- ↑ N. Calvet et al; The Astronomical Journal 129:935–946 (2005)
- ↑ J. Hernandez et al., Astrophys. J. 652:472-481 (2006)