113 citations · 418 across the 29 of their papers we have counts for
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The Nature of the Emission Spectrum of NGC 7793 P13: modeling the atmosphere of the donor star
A. S. Vinokurov, A. E. Kostenkov, K. E. Atapin +1
We continue to study the ultra-luminous X-ray source NGC 7793 P13 in the optical range. In this work, we are testing the model of a spherically symmetric wind atmosphere of the don…
Discovery of An X-ray Photoionized Optical Nebula and A Radio Nebula Associated with the ULX NGC 4861 X-1
Hang Gong, Ryan Urquhart, Alexandr Vinokurov +5
We have conducted long-slit spectroscopic observations and analyzed archival radio data for the ultraluminous X-ray source (ULX) NGC 4861 X-1. Our spectral line analysis unveils th…
Optical Counterparts of Two Candidate Ultraluminous X-ray Sources in NGC 4536
H. Avdan, E. Sonbas, K. S. Dhuga +7
Archival {\it XMM-Newton}, {\it Chandra} and {\it Hubble Space Telescope (HST)} data have been used to study the X-ray and optical properties of two candidate ultraluminous X-ray s…
Simultaneous X-ray/UV observations of ultraluminous X-ray source Holmberg II X-1 with Indian space mission AstroSat
A. Vinokurov, K. Atapin, O. P. Bordoloi +11
We present the results of 8 epochs of simultaneous UV and X-ray observations of the highly variable ultraluminous X-ray source (ULX) Holmberg II X-1 with AstroSat -- Indian multiwa…
Optical Counterparts of ULXs in Two Dwarf Galaxies: NGC 4861 and NGC 4449
M. Ozdogan Ela, A. Akyuz, N. Aksaker +7
We present the results of a search for optical candidates of Ultraluminous X-ray sources (ULXs) in two dwarf galaxies: NGC 4861 and NGC 4449 using Hubble Space Telescope {\it HST}…
NGC 5474 X-1: a neutron star ULX in an old stellar cluster?
Kirill Atapin, Alexander Vinokurov, Arkadiy Sarkisyan +4
We present the optical and X-ray study of the ultraluminous X-ray source (ULX) NGC 5474 X-1. The X-ray spectrum taken during the bright state of the source ($L_X \sim 2\times10^{40…
Determining parameters of ULXs with model grids of extended atmospheres
A. Kostenkov, A. Vinokurov, Y. Solovyeva
In current work we continued study of wind parameters of ultraluminous X-ray sources (ULXs) using model grids of extended atmospheres. We present sets of models with temperatures f…
Observations of ultraluminous X-ray sources with the 6-m telescope of the SAO RAS
A. Vinokurov, K. Atapin, Y. Solovyeva +2
The nature of ultraluminous X-ray sources (ULXs) is not yet fully understood but it can be done in the most efficient way by analyzing its optical emission and environment. We pres…
Modeling of extended atmospheres with temperatures below 40000K
A. Kostenkov, A. Vinokurov, Y. Solovyeva +2
We calculate models of extended stellar atmospheres with a temperature in the range of 12000-40000K and a mass loss rate of yr. A large number of…
Optical Counterpart to the Ultraluminous X-Ray Source in the UGC6456 Galaxy
Alexander Vinokurov, Kirill Atapin, Yulia Solovyeva
We report the identification of the optical counterpart to the transient ultraluminuos X-ray source in the blue dwarf galaxy UGC6456 (VII Zw 403). The source is highly variable in…
Optical Counterparts of ULXs and Their Host Environments in NGC 4490/4485
Senay Avdan, Aysun Akyuz, Alexander Vinokurov +6
We report the identification of the possible optical counterparts of five out of seven Ultraluminous X-ray Sources (ULXs) in NGC 4490/4485 galaxy pair. Using archival Hubble Space…
Optical counterparts of two ultraluminous X-ray sources NGC4559 X-10 and NGC4395 ULX-1
A. Vinokurov, S. Fabrika, K. Atapin
We study the optical counterparts of ultraluminous X-ray sources NGC4559 X-10 and NGC4395 ULX-1. Their absolute magnitudes, after taking the reddening into account, are $M_V \appro…
Ultraluminous X-ray sources as super-Eddington accretion disks
Sergei Fabrika, Alexander Vinokurov, Kirill Atapin
The origin of Ultraluminous X-ray sources (ULXs) in external galaxies whose X-ray luminosities exceed those of the brightest black holes in our Galaxy by hundreds and thousands of…
Supercritical Accretion Discs in Ultraluminous X-ray Sources and SS 433
Sergei Fabrika, Yoshihiro Ueda, Alexander Vinokurov +2
The black hole mass and accretion rate in Ultraluminous X-ray sources (ULXs) in external galaxies, whose X-ray luminosities exceed those of the brightest black holes in our Galaxy…
Optical counterparts of two ULXs in NGC5474 and NGC3627 (M66)
S. Avdan, A. Vinokurov, S. Fabrika +6
We identified two optical counterparts of brightest ultraluminous X-ray Sources (ULXs) in galaxies NGC5474 and NGC3627 (M66). The counterparts in Hubble Space Telescope images are…
X-ray variability of SS433: effects of the supercritical accretion disc
Kirill Atapin, Sergei Fabrika, Aleksei Medvedev +1
We study a stochastic variability of SS433 in the Hz frequency range based on RXTE data, and on simultaneous observations with RXTE and optical telescop…
Ultra-luminous X-ray Sources as Supercritical Accretion Disks: Spectral Energy Distributions
A. Vinokurov, S. Fabrika, K. Atapin
We describe a model of spectral energy distribution in supercritical accretion disks (SCAD) based on the conception by Shakura and Sunyaev. We apply this model to five ultra-lumino…