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Clumped stellar winds in supergiant HMXBs

Clumped stellar winds in supergiant HMXBs. ArXiv: 1201.1951v1 Oskinova et. al. Reporter: Zhang Zhen 2012.3.13. Outlines. Introduction The CAK model Bondi-Hoyle-Lyttleton accretion Simulations and paradox Modification and results Conclusion. Introduction. Theories about clumpy wind

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Clumped stellar winds in supergiant HMXBs

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  1. Clumped stellar winds in supergiant HMXBs ArXiv: 1201.1951v1 Oskinova et. al. Reporter: Zhang Zhen 2012.3.13

  2. Outlines • Introduction • The CAK model • Bondi-Hoyle-Lyttleton accretion • Simulations and paradox • Modification and results • Conclusion

  3. Introduction • Theories about clumpy wind • CAK: line scattering 2500km/s • Owocki et al. 1988: numerical simulation Small-amplitude perturbation  Highly structured wind • Runacres & Owocki 2002 Evolution of wind structures  Inhomogeneous

  4. Introduction • Observations about clumpy wind • Prinja & Massa (2010)

  5. Introduction • Clumpy wind in supergiant HMXBs • van der Meer et al. (2005): 4U1700-37 • SFXT • Furst et al. (2010): Vela X-1

  6. Purpose • Bridge the gap between detailed models of inhomogeneous stellar winds in single stars and the phenomenological description of donor winds in supergiant high-mass X-ray binaries (HMXBs).

  7. CAK model

  8. CAK • Main idea: scattering of line radiation • Basic equations for the stellar envelope • Mass conservation: • Momentum balance: • Equation of state

  9. About • Castor, 1974, MNRAS, 169, 279

  10. CAK result

  11. Results • For a class O5

  12. Bondi accretion

  13. BHL accretion • Reviewed by Edgar (2004) & Negueruela (2009) • Bondi radius: • Accretion rate

  14. Simulations and paradox

  15. HYDRODYNAMICAL SIMULATIONS • Feldmeier et al. (1997a,b): hydrodynamical simulations of the line driven stellar wind

  16. L_x: a change up to eight orders of magnitude

  17. Modification and results

  18. Background • Microclumping: optically thin Leads to smaller mass-loss rate Hillier 1991; Hamann & Koesterke 1998 Bouret et al. (2005) and Fullerton et al. (2006) • Modification: Photo-ionization Absorption

  19. Photo-ionization • Neglecting absorption, the mean primary photon intensity at frequency v at a distance r: •  • Photo-ionization parameter:

  20. Absorption

  21. Calculation • 2_D stochastic wind model: Oskinova et al. (2004) Feldmeier et al. (1997a,b) + Absorption • Notation: 1. spherically symmetric 2. solid angle 3. “balls” & “pancakes” 4. no self-absorption & no re-emission. 5. edge on system

  22. Results

  23. Thanks

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