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Wolf-Rayet Stars & the Luminous Blue Variables 2014/11/12 Wednesday Luqian Wang

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Outline Definition/General properties History Classification: Optical/UV-FUV/Infrared Luminous Blue Variables (LBVs)

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Definitions/General Properties Definition: Hot, luminous stars whose spectacular spectra are dominated by emission lines formed in a massive stellar wind Evolved descendent of the most massive star Mass: [10,25] Msun, T: [3E4, 2E5] K Mass loss rate: ~E-5 Msun/year Nitrogen sequence (WN), Carbon sequence (WC) End of lives: supernova explosion

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History 1837, Charles Wolf & Georges Rayet Cygnus: HD191765 (Vogel,1883), HD192103, HD192641 Carlye Beals, Dominion Astrophysical Observatory (1934,1938) Smith (1968) Smith, Shara & Moffat (1996)

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Outline Definition/General properties History Classification: Optical/UV-FUV/Infrared Luminous Blue Variables (LBVs)

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WN classification Ionization state of N predominates in the spectrum (P443, Gray & Corbally ) Hamann, Koesterke & Wessolowski (1995): a absorption lines; -w/-s weak/strong emission lines (EW of He II-5412, 37 Angstrom)

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WC classification Line judgments: Crowther et al. (1998) : WC8-WC11 Please see Table 11.2

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WO classification Judgment lines: Kingsburgh, Barlow & Storey (1995) Crowther et al. (1998) Result of high-ionization of oxygen, rather than increased O abundance High-ionization extension of WC stars Please see Table 11.3

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Outline Definition/General properties History Classification: Optical/UV-FUV/Infrared Luminous Blue Variables (LBVs)

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Ultraviolet : WN WR stars emit most of their radiation in UV/FUV International Ultraviolet Explorer ( IUE ): wavelength: [1150,3250] Angstrom low resolution: ~6.0 Angstrom blended lines

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Ultraviolet: WC Line indicators:

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Far Ultraviolet (FUV) Far Ultraviolet Spectroscopic Explorer ( FUSE ) wavelength: [905,1188] Angstrom Resolution: ~0.05 Angstrom Issue: < 1000 Angstrom, interstellar absorptions.

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FUSE WN

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FUSE WC

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Outline Definition/General properties History Classification: Optical/UV-FUV/Infrared Luminous Blue Variables (LBVs)

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Late WN

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Early WN

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Late WC

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Early WC

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Outline Definition/General properties History Classification: Optical/UV-FUV/Infrared Luminous Blue Variables (LBVs)

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Luminous Blue Variables (LBVs) LBV (S Doradus): Evolved, massive, and extremely luminous supergiant that is subject to instabilities that result in eruptions of various sorts. e.g. eta Carinae, P Cygni Eruption optical thick, expanded atmosphere, i.e. Pseudo photosphere Quiescent (minimum light state) : T>15,000 K Eruption (maximum light state): T~[7000,8000] K

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LBVs on HR-diagram

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O, WR, & LBV relation? WR stars and LBVs: high mass loss rate, high luminosities, & close association w/star formation Evolutionary scenario:

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Thank you!