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The Orion OB1 stellar association is a contingent group of several dozen hot giant stars of spectral types O and B. Associated are thousands of lower-mass stars, and a (smaller but significant) number of protostars. It is part of the larger Orion Molecular Cloud Complex. Owing to its relative closeness and complexity it is the most closely studied OB association.[1]
Structure
[edit]"OB Associations play an important role in the large scale propagation of star formation and in the shaping and evolution of the interstellar medium".[1]
The Orion OB1 association consists of the following subgoups:[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 sub-group is a sub-association known as the 25 Orionis group.[3][4]
- 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 approximately 8 million years is further subdivided into three subgroups.[5][6]
- Orion OB1c - the stars in Orion's Sword, 3-6 million years old
- Orion OB1d - the stars of the Orion Nebula and M43 (the youngest stars)
Signatures of stellar debris disk evolution have been detected in the 1a and 1b subgroups.[7][8]
Source Material
[edit]References
[edit]- ^ a b c Brown, A. G. A.; de Geus, E. J.; de Zeeuw, P. T. (September 1994). "The Orion OB1 association. 1: Stellar content" (PDF). Astronomy and Astrophysics. 289 (1): 101–120. arXiv:astro-ph/9403051. Bibcode:1994A&A...289..101B. ISSN 0004-6361. Retrieved 2010-11-18.
{{cite journal}}: CS1 maint: date and year (link) CS1 maint: multiple names: authors list (link) - ^ Blaauw, Adriaan (1964). "The O Associations in the Solar Neighborhood" (PDF). Astronomy and Astrophysics. 2: 213–246. Bibcode:1964ARA&A...2..213B. doi:10.1146/annurev.aa.02.090164.001241. Retrieved 2010-11-18.
- ^ Briceño, César; Hartmann, Lee; Hernández, Jesús; Calvet; et al. (June 2007). "25 Orionis: A Kinematically Distinct 10 Myr Old Group in Orion OB1a" (PDF). The Astronomical Journal. 661 (2): 1119–1128. arXiv:astro-ph/0701710. Bibcode:2007ApJ...661.1119B. doi:10.1086/513087. Retrieved 2010-11-07.
{{cite journal}}: Explicit use of et al. in:|author=(help)CS1 maint: date and year (link) CS1 maint: multiple names: authors list (link) - ^ Harper, Graham M.; Brown, Alexander; Guinan, Edward F. (April 2008). "A New VLA-Hipparcos Distance to Betelgeuse and its Implications" (PDF). The Astronomical Journal. 135 (4): 1430–40. Bibcode:2008AJ....135.1430H. doi:10.1088/0004-6256/135/4/1430. Retrieved 2010-11-07.
{{cite journal}}: CS1 maint: date and year (link) CS1 maint: multiple names: authors list (link) - ^ W.H. Warren and J.E. Hesser, ApJS 34, 115ff (1977)
- ^ W.H. Warren and J.E. Hesser, ApJS 36, 497ff (1978)
- ^ N. Calvet et al., The Astronomical Journal 129:935–946 (2005)
- ^ J. Hernandez et al., Astrophys.J. 652:472-481 (2006)
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