Clumped stellar winds in supergiant HMXBs
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Transcript of Clumped stellar winds in supergiant HMXBs
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Clumped stellar winds in supergiant HMXBs
ArXiv: 1201.1951v1Oskinova et. al.
Reporter: Zhang Zhen2012.3.13
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Outlines
• Introduction
• The CAK model
• Bondi-Hoyle-Lyttleton accretion
• Simulations and paradox
• Modification and results
• Conclusion
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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
7 110 sunM M yr
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Introduction
• Observations about clumpy wind
• Prinja & Massa (2010)
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Introduction• Clumpy wind in supergiant HMXBs
• van der Meer et al. (2005): 4U1700-37
• SFXT
• Furst et al. (2010): Vela X-1
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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).
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CAK model
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CAK
• Main idea: scattering of line radiation
• Basic equations for the stellar envelope • Mass conservation:• Momentum balance:
• Equation of state
2 2
1[1 ( )]
4ge
dpLdv Gmv M tdr r r c dr
24 tandm
r v cons tdt
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About
• Castor, 1974, MNRAS, 169, 279
( )erad
Ff M t
c
( )M t
( )M t kt
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CAK result
(1 )/ 1/ 1/ (1 )/4(1 ) (1 )
e th
dm Gmk
dt v
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Results
• For a class O5 6
11
60
9.66 10
0.4449290
9.585 10 13.8
sun
sun
e
eff
sun
m m
L L
L
GmcT K
R cm R
20 14.16 10dm
gsdt
1 1
4 3mst dm
m dt
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Bondi accretion
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BHL accretion
• Reviewed by
Edgar (2004) & Negueruela (2009)
• Bondi radius:
• Accretion rate 24 acc wM r v
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Simulations and paradox
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HYDRODYNAMICAL SIMULATIONS
• Feldmeier et al. (1997a,b): hydrodynamical simulations of the line driven stellar wind
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L_x: a change up to eight orders of magnitude
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Modification and results
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Background
• Microclumping: optically thin
Leads to smaller mass-loss rate Hillier 1991; Hamann & Koesterke 1998 Bouret e
t al. (2005) and Fullerton et al. (2006)
• Modification:
Photo-ionization
Absorption
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Photo-ionization
• Neglecting absorption, the mean primary photon intensity at frequency v at a distance r:
•
• Photo-ionization parameter:
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Absorption
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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
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Results
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Thanks