In the very late stages of AGB evolution, a star develops a super-wind with extreme mass loss. The gas in the stellar wind condenses as it cools away from the star, forming molecules such as water (H2O) and silicon monoxide (SiO). This can form grains of dust, mostly silicates, which obscure the star at shorter wavelengths, leading to a strong infrared source.[1]Hydroxyl (OH) radicals can be produced by photodissociation or collisional dissociation.[2]
H2O and OH can both be pumped to produce maser emission. OH masers in particular can give rise to a powerful maser action at 1612 MHz and this is regarded as a defining feature of the OH/IR stars. Many other AGB stars such as Mira variables show weaker OH masers at other wavelengths, such as 1667MHz or 22MHz.[3]
^Kemper, F.; De Koter, A.; Waters, L. B. F. M.; Bouwman, J.; Tielens, A. G. G. M. (2002). "Dust and the spectral energy distribution of the OH/IR star OH 127.8+0.0: Evidence for circumstellar metallic iron". Astronomy and Astrophysics. 384 (2): 585. arXiv:astro-ph/0201128. Bibcode:2002A&A...384..585K. doi:10.1051/0004-6361:20020036. S2CID 17649812.
^Goldreich, P.; Scoville, N. (1976). "OH-IR stars. I - Physical properties of circumstellar envelopes" (PDF). Astrophysical Journal. 205: 144. Bibcode:1976ApJ...205..144G. doi:10.1086/154257.
^Lewis, B. M. (2002). "On Dead OH/IR Stars". The Astrophysical Journal. 576 (1): 445–449. Bibcode:2002ApJ...576..445L. doi:10.1086/341534.
^Bowers, P. F. (December 1981). "Supergiant OH/IR stars". The Astronomical Journal. 86: 1930–1934. Bibcode:1981AJ.....86.1930B. doi:10.1086/113074. ISSN 0004-6256.
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star, this, article, includes, list, general, references, lacks, sufficient, corresponding, inline, citations, please, help, improve, this, article, introducing, more, precise, citations, june, 2020, learn, when, remove, this, template, message, asymptotic, gi. This article includes a list of general references but it lacks sufficient corresponding inline citations Please help to improve this article by introducing more precise citations June 2020 Learn how and when to remove this template message An OH IR star is an asymptotic giant branch AGB or a red supergiant or hypergiant RSG or RHG star that shows strong OH maser emission and is unusually bright at near infrared wavelengths Very Large Telescope image of the surroundings of the red hypergiant VY Canis Majoris In the very late stages of AGB evolution a star develops a super wind with extreme mass loss The gas in the stellar wind condenses as it cools away from the star forming molecules such as water H2O and silicon monoxide SiO This can form grains of dust mostly silicates which obscure the star at shorter wavelengths leading to a strong infrared source 1 Hydroxyl OH radicals can be produced by photodissociation or collisional dissociation 2 H2O and OH can both be pumped to produce maser emission OH masers in particular can give rise to a powerful maser action at 1612 MHz and this is regarded as a defining feature of the OH IR stars Many other AGB stars such as Mira variables show weaker OH masers at other wavelengths such as 1667MHz or 22MHz 3 Examples EditOH IR stars Edit R Aquilae QX Puppis WX Piscium V437 Scuti V669 Cassiopeiae W43A NSV 25875 V1300 Aquilae V1366 Aquilae V1365 Aquilae GX Monocerotis IW Hydrae SY Aquilae OH IR supergiants 4 Edit S Persei AH Scorpii MY Cephei IRC 30308 PZ Cassiopeiae VX Sagittarii a NML Cygni VY Canis Majoris IRC 10420Notes Edit Later found to be an AGB star References Edit Kemper F De Koter A Waters L B F M Bouwman J Tielens A G G M 2002 Dust and the spectral energy distribution of the OH IR star OH 127 8 0 0 Evidence for circumstellar metallic iron Astronomy and Astrophysics 384 2 585 arXiv astro ph 0201128 Bibcode 2002A amp A 384 585K doi 10 1051 0004 6361 20020036 S2CID 17649812 Goldreich P Scoville N 1976 OH IR stars I Physical properties of circumstellar envelopes PDF Astrophysical Journal 205 144 Bibcode 1976ApJ 205 144G doi 10 1086 154257 Lewis B M 2002 On Dead OH IR Stars The Astrophysical Journal 576 1 445 449 Bibcode 2002ApJ 576 445L doi 10 1086 341534 Bowers P F December 1981 Supergiant OH IR stars The Astronomical Journal 86 1930 1934 Bibcode 1981AJ 86 1930B doi 10 1086 113074 ISSN 0004 6256 This star related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title OH IR star amp oldid 1089546507, wikipedia, wiki, book, books, library,
