Interpretation of orbital light curves of U Geminorum

Khruzina, T. S.; Черепащук, А. М.; Бисикало, Д. В.; Boyarchuk, A. A.; Кузнецов, О. А.

doi:10.1134/1.1618997

Cited by 32 publications

(38 citation statements)

References 23 publications

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“…Roche lobe overflow usually leads to an accretion disk and wind. Long-term observation revealed precession effects in the Voptical light curve (see Khruzina & Cherepashchuk 1983), which can be interpreted as an indication of a disk component in accretion flow.…”

Section: Introductionmentioning

confidence: 98%

X-Ray Spectra of the High-Mass X-Ray Binary 4u 1700-37 Using Bepposax, Suzaku, and Rxte Observations

Seifina

Titarchuk

Shaposhnikov

2016

ApJ

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We present an X-ray spectral analysis of the high-mass binary 4U1700-37 during its hard-soft state evolution. We use BeppoSAX, Suzaku, and Rossi X-ray Timing Explorer observations for this investigation. We argue that the X-ray broadband spectra during all of the spectral states can be adequately reproduced by a model consisting of a low-temperature blackbody component, two Comptonized components which are both due to the presence of a Compton cloud (CC) that up-scatters seed photons of T s1 1.4 keV and T s2 <1 keV, and an iron-line component. Using this model, we find that the photon power-law index is almost constant, Γ 1 ∼2 for all spectral states. However, Γ 2 shows behavior that is dependent on the spectral state. Namely, Γ 2 is quasi-constant at the level of Γ 2 ∼2 while the CC plasma temperature kT e 2 ( ) is less than 40 keV; on the other hand, Γ 2 is in the range of 1.3<Γ 2 <2 when kT e 2 ( ) is greater than 40 keV. We explain this quasi-stability of Γ during most of the hard-soft transitions of 4U1700-37 in the framework of a model in which the resulting spectrum is described by two Comptonized components. We find that these Comptonized spectral components of the high-mass X-ray binaries 4U1700-37 are similar to those previously found in neutron star (NS) sources. This index dependence versus both the mass accretion rate and kT e revealed in 4U1700-37 is universal observational evidence for the presence of an NS in 4U 1700-37.

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Section: Introductionmentioning

confidence: 98%

X-Ray Spectra of the High-Mass X-Ray Binary 4u 1700-37 Using Bepposax, Suzaku, and Rxte Observations

Seifina

Titarchuk

Shaposhnikov

2016

ApJ

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“…This region, called hot line, is a result of the interaction of the disk halo and the inter-component envelope with the gas stream and allows one to fit the whole light curves of the nova-like stars, including the variability of their out-of-eclipse parts (Khruzina 2001;Khruzina et al 2003).…”

Section: Introductionmentioning

confidence: 99%

The SW Sextantis-type star 2MASS J01074282+4845188: an unusual bright accretion disk with non-steady emission and a hot white dwarf

Khruzina

Dimitrov

Kjurkchieva

2013

A&A

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Context. Cataclysmic variables (CVs) present a short evolutional stage of binary systems. The nova-like stars are rare objects, especially those with eclipses (only several tens). But precisely these allow to determine the global parameters of their configurations and to learn more about the late stage of stellar evolution. Aims. The light curve solution allows one to determine the global parameters of the newly discovered nova-like eclipsing star 2MASS J01074282+4845188 and to estimate the contribution of the different light sources. Methods. We present new photometric and spectral observations of 2MASS J01074282+4845188. To obtain a light curve solution we used a model of a nova-like star whose emission sources are a white dwarf surrounded by an accretion disk, a secondary star filling its Roche lobe, a hot spot and a hot line. The obtained global parameters are compared with those of the eclipsing nova-like UX UMa. Results. 2MASS J01074282+4845188 shows the deepest permanent eclipse among the known nova-like stars. It is reproduced by covering the very bright accretion disk by the secondary component. The luminosity of the disk is much bigger than that of the rest light sources. The determined high temperature of the disk is typical for that observed during the outbursts of CVs. The primary of 2MASS J01074282+4845188 is one of the hottest white dwarfs in CVs. The temperature of 5090 K of its secondary is also quite high and more appropriate for a long-period SW Sex star. It might be explained by the intense heating from the hot white dwarf and the hot accretion disk of the target. Conclusions. The high mass accretion rateṀ = 8 × 10 −9 M yr −1 , the broad and single-peaked Hα emission profile, and the presence of an S-wave are sure signs for the SW Sex classification of 2MASS J01074282+4845188. The obtained flat temperature distribution along the disk radius as well as the deviation of the energy distribution from the black-body law are evidence of the non-steady emission of the disk. It can be attributed to the low viscosity of the disk matter due to its unusual high temperature. The close values of the disk temperature and the parameter α g of 2MASS J01074282+4845188 and those of the cataclysmic stars at eruptions might be considered as an additional argument for the permanent active state of nova-like stars.

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“…The highest accuracy for the black hole mass is claimed by Gelino et al (2001b) and Khruzina et al (2003): M bh = 6.95 ± 0.6 M and M bh = 7.15 ± 0.45 M , respectively. Gelino et al (2001b) estimate the distance as 5.1 kpc or even 5.9 kpc (Gelino 2004).…”

Section: Distance To Grs 1124-68mentioning

confidence: 95%

Modeling of non-stationary accretion disks in X-ray novae A 0620–00 and GRS 1124–68 during outburst

Suleimanov

Lipunova

Шакура

2008

A&A

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Aims. We address the task of modeling soft X-ray and optical light curves of X-ray novae in the high/soft state. Methods. The analytic model of viscous evolution of an externally truncated accretion α-disk is used. Relativistic effects near a Kerr black hole and self-irradiation of an accretion disk are taken into account. Results. The model is applied to the outbursts of X-ray nova Monocerotis 1975 (A 0620−00) and X-ray nova Muscae 1991 (GRS 1124−68). Comparison of observational data with the model yields constraints on the angular momentum (the Kerr parameter) of the black holes in A 0620−00 and GRS 1124−68: 0.3−0.6 and ≤0.4, and on the viscosity parameter α of the disks: 0.7−0.95 and 0.55−0.75. We also conclude that the accretion disks should have an effective geometrical thickness 1.5−2 times greater than the theoretical value of the distance between the photometric layers.

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Interpretation of orbital light curves of U Geminorum

Cited by 32 publications

References 23 publications

X-Ray Spectra of the High-Mass X-Ray Binary 4u 1700-37 Using Bepposax, Suzaku, and Rxte Observations

X-Ray Spectra of the High-Mass X-Ray Binary 4u 1700-37 Using Bepposax, Suzaku, and Rxte Observations

The SW Sextantis-type star 2MASS J01074282+4845188: an unusual bright accretion disk with non-steady emission and a hot white dwarf

Modeling of non-stationary accretion disks in X-ray novae A 0620–00 and GRS 1124–68 during outburst

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