scholarly journals Accretion from Stellar Winds

1988 ◽  
Vol 103 ◽  
pp. 149-160
Author(s):  
Mario Livio
Keyword(s):  
Angular Momentum ◽  
Inhomogeneous Medium ◽  
Accretion Disk ◽  
Stellar Wind ◽  
Optical Observations ◽  
Stellar Winds ◽  
X Ray ◽  
Disk Formation ◽  
X Ray Binaries

AbstractRecent calculations have demonstrated that accretion from a stellar wind is very probably unsteady. The average rate of accretion of angular momentum is lower by about a factor 5 than the rate at which angular momentum is deposited into the Bondi-Hoyle accretion cylinder. This makes disk formation from wind accretion very difficult, in particular in the case of massive x-ray binaries. A combination of x-ray, uv and optical observations of symbiotic and related systems, as well as spin-up information on x-ray binaries, can be used to determine whether an accretion disk does form. Such observations can provide us with valuable information on the process of accretion from an inhomogeneous medium.

scholarly journals Supergiant fast X-ray transients versus classical supergiant high mass X-ray binaries: Does the difference lie in the companion wind?

2018 ◽  
Vol 610 ◽  
pp. A50 ◽  
Author(s):  
P. Pradhan ◽  
E. Bozzo ◽  
B. Paul
Keyword(s):  
Stellar Wind ◽  
Equivalent Width ◽  
High Mass ◽  
Stellar Winds ◽  
Data Set ◽  
Iron Line ◽  
X Ray ◽  
Eclipse Observations ◽  
The Difference ◽  
X Ray Binaries

We present a comparative study of stellar winds in classical supergiant high mass X-ray binaries (SgXBs) and supergiant fast X-ray transients (SFXTs) based on the analysis of publicly available out-of-eclipse observations performed with Suzaku and XMM-Newton. Our data set includes 55 observations of classical SgXBs and 21 observations of SFXTs. We found that classical SgXBs are characterized by a systematically higher absorption and luminosity compared to the SFXTs, confirming the results of previous works in the literature. Additionally, we show that the equivalent width of the fluorescence Kα iron line in the classical SgXBs is significantly larger than that of the SFXTs (outside X-ray eclipses). Based on our current understanding of the physics of accretion in these systems, we conclude that the most likely explanation of these differences is ascribed to the presence of mechanisms inhibiting accretion most of the time in SFXTs, thereby leading to a much less efficient photoionization of the stellar wind compared to classical SgXBs. We do not find evidence for the previously reported anticorrelation between the equivalent width of the fluorescence iron line and the luminosity of SgXBs.

scholarly journals Clumped stellar winds in supergiant high-mass X-ray binaries

2012 ◽  
Vol 8 (S290) ◽  
pp. 287-288 ◽  
Author(s):  
L. M. Oskinova ◽  
A. Feldmeier ◽  
P. Kretschmar
Keyword(s):  
Stellar Wind ◽  
Compact Object ◽  
Time Dependent ◽  
High Mass ◽  
Stellar Winds ◽  
Degree Of Ionization ◽  
X Ray ◽  
Wind Theory ◽  
Supergiant Star ◽  
X Ray Binaries

AbstractThe clumping of massive star winds is an established paradigm, which is confirmed by multiple lines of evidence and is supported by stellar wind theory. We use the results from time-dependent hydrodynamical models of the instability in the line-driven wind of a massive supergiant star to derive the time-dependent accretion rate on to a compact object in the Bondi-Hoyle-Lyttleton approximation. The strong density and velocity fluctuations in the wind result in strong variability of the synthetic X-ray light curves. Photoionization of inhomogeneous winds is different from the photoinization of smooth winds. The degree of ionization is affected by the wind clumping. The wind clumping must also be taken into account when comparing the observed and model spectra of the photoionized stellar wind.

scholarly journals The dark side of supergiant High-Mass X-ray Binaries

2018 ◽  
Vol 14 (S346) ◽  
pp. 161-169
Author(s):  
Sylvain Chaty ◽  
Francis Fortin ◽  
Federico García ◽  
Federico Fogantini
Keyword(s):  
Angular Momentum ◽  
Stellar Wind ◽  
Compact Object ◽  
High Mass ◽  
Dark Side ◽  
Companion Star ◽  
X Ray ◽  
Active Stars ◽  
Multi Wavelength ◽  
X Ray Binaries

Abstract. High Mass X-ray Binaries (HMXB) have been revealed by a wealth of multi-wavelength observations, from X-ray to optical and infrared domain. After describing the 3 different kinds of HMXB, we focus on 3 HMXB hosting supergiant stars: IGR J16320-4751, IGR J16465-4507 and IGR J16318-4848, respectively called “The Good”, “The Bad” and “The Ugly”. We review in these proceedings what the observations of these sources have brought to light concerning our knowledge of HMXB, and what part still remains in the dark side. Many questions are still pending, related to accretion processes, stellar wind properties in these massive and active stars, and the overall evolution due to transfer of mass and angular momentum between the companion star and the compact object. Future observations should be able to answer these questions, which constitute the dark side of HMXB.

scholarly journals Ionization effects in stellar winds of massive X-ray binaries

1981 ◽  
Vol 59 ◽  
pp. 457-460
Author(s):  
G. Hammerschlag-Hensberge
Keyword(s):  
High Resolution ◽  
Stellar Wind ◽  
Ultraviolet Spectroscopy ◽  
Stellar Winds ◽  
Density Structure ◽  
Early Type ◽  
X Ray ◽  
Ionization Structure ◽  
X Ray Binaries

AbstractHigh resolution ultraviolet spectroscopy of the early-type X-ray binary Vela X-l/HD 77581 provides a unique example to study the ionization structure of the stellar wind which varies under influence of the X-ray source. New results for other early-type X-ray binaries will be presented and compared with the Vela X-1 model. These results show that the observed variations strongly depend on the intensity of the X-ray source and on the density structure of the stellar wind.

Iron K-Line Emission from X-Ray Binaries

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase
Keyword(s):  
Accretion Disk ◽  
Radiative Recombination ◽  
Characteristic Temperature ◽  
Line Emission ◽  
Ionization Front ◽  
Continuum Radiation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx> 10 keV is likely due to fluorescence outside the He II ionization front.

scholarly journals X-Ray Determination of the Black-Hole Mass in Cygnus X-1

1998 ◽  
Vol 188 ◽  
pp. 388-389
Author(s):  
A. Kubota ◽  
K. Makishima ◽  
T. Dotani ◽  
H. Inoue ◽  
K. Mitsuda ◽  
...  
Keyword(s):  
Black Hole ◽  
Compact Object ◽  
Optical Observations ◽  
Black Hole Mass ◽  
X Ray ◽  
Upper Limit ◽  
Supergiant Star ◽  
X Ray Binaries ◽  
Two Bodies

About 10 X-ray binaries in our Galaxy and LMC/SMC are considered to contain black hole candidates (BHCs). Among these objects, Cyg X-1 was identified as the first BHC, and it has led BHCs for more than 25 years(Oda 1977, Liang and Nolan 1984). It is a binary system composed of normal blue supergiant star and the X-ray emitting compact object. The orbital kinematics derived from optical observations indicates that the compact object is heavier than ~ 4.8 M⊙ (Herrero 1995), which well exceeds the upper limit mass for a neutron star(Kalogora 1996), where we assume the system consists of only two bodies. This has been the basis for BHC of Cyg X-1.

4U 1608–52 as a quasi-persistent X-ray source

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Vojtěch Šimon
Keyword(s):  
Accretion Disk ◽  
Time Segment ◽  
X Ray ◽  
Band Emission ◽  
Heating And Cooling ◽  
Soft State ◽  
Cyclic Variations ◽  
Low Mass ◽  
X Ray Binaries ◽  
Disk Region

Abstract 4U 1608–52 is a soft X-ray transient. The analysis presented here of a particular part of its X-ray activity uses observations of RXTE/ASM and Swift/BAT. We show a time segment (MJD 54262–MJD 55090) (828 d) in which 4U 1608–52 behaved as a quasi-persistent X-ray source with a series of bumps, with a complicated relation between the evolution of fluxes in the soft (1.5–12 keV) and the hard (15–50 keV) X-ray regions. We ascribe these bumps to a series of propagations of heating and cooling fronts over the inner disk region without any transitions to the true quiescence. 4U 1608–52 oscillated around the boundary between the dominance of the Comptonized component and the dominance of the multicolor accretion disk in its luminosity. Only some of the bumps in this series were accompanied by a transition from the hard to the soft state; if it occurred, it displayed a strong hysteresis effect. The hard-band emission with the dominant Comptonized component was present for most of this active state and showed a cycle of about 40 d. We argue that the cyclic variations of flux come from the inner disk region, not, e.g., from a jet. We also discuss the observed behavior of 4U 1608–52 in the context of other quasi-persistent low-mass X-ray binaries.

New optical observations of 2S 0921-630 and its relation to other X-ray binaries

1981 ◽  
Vol 30 (1-4) ◽  
pp. 365-366
Author(s):  
C. Chevalier ◽  
S. A. Ilovaisky
Keyword(s):  
Optical Observations ◽  
X Ray ◽  
X Ray Binaries
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