Optical, J, and K light curves of XTE J1118+480 = KV UMa: the mass of the black hole and the spectrum of the non-stellar component. (arXiv:1909.06358v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Cherepashchuk_A/0/1/0/all/0/1">A. M. Cherepashchuk</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Katysheva_N/0/1/0/all/0/1">N. A. Katysheva</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Khruzina_T/0/1/0/all/0/1">T. S. Khruzina</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shugarov_S/0/1/0/all/0/1">S. Yu. Shugarov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tatarnikov_A/0/1/0/all/0/1">A. M. Tatarnikov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bogomazov_A/0/1/0/all/0/1">A. I. Bogomazov</a>
Optical, J, and K photometric observations of the KV UMa black hole X-ray
nova in its quiescent state obtained in 2017-2018 are presented. A significant
flickering within light curves was not detected, although the average
brightness of the system faded by $approx 0.1^m$ during 350 days. Changes in
the average brightness were not accompanied with the increase or the decrease
of the flickering. From the modelling of five light curves the inclination of
the KV UMa orbit and the black hole mass were obtained: $i=74^{circ}pm
4^{circ}$, $M_{BH}=(7.06div 7.24)M_{odot}$ dependently on the used mass
ratio. The non-stellar component of the spectrum in the range $lambda=6400div
22000$r{A} can be fitted by a power law $F_{lambda}sim lambda^{alpha}$,
$alphaapprox -1.8$. The accretion disk orientation angle changed from one
epoch to another. The model with spots on the star was inadequate. Evolutionary
calculations using the “Scenario Machine” code were performed for low mass
X-ray binaries, a recently discovered anomalously rapid decrease of the orbital
period was taken into account. We showed that the observed decrease can be
consistent with the magnetic stellar wind of the optical companion which
magnetic field was increased during the common envelope stage. Several
constraints on evolutionary scenario parameters were done.
Optical, J, and K photometric observations of the KV UMa black hole X-ray
nova in its quiescent state obtained in 2017-2018 are presented. A significant
flickering within light curves was not detected, although the average
brightness of the system faded by $approx 0.1^m$ during 350 days. Changes in
the average brightness were not accompanied with the increase or the decrease
of the flickering. From the modelling of five light curves the inclination of
the KV UMa orbit and the black hole mass were obtained: $i=74^{circ}pm
4^{circ}$, $M_{BH}=(7.06div 7.24)M_{odot}$ dependently on the used mass
ratio. The non-stellar component of the spectrum in the range $lambda=6400div
22000$r{A} can be fitted by a power law $F_{lambda}sim lambda^{alpha}$,
$alphaapprox -1.8$. The accretion disk orientation angle changed from one
epoch to another. The model with spots on the star was inadequate. Evolutionary
calculations using the “Scenario Machine” code were performed for low mass
X-ray binaries, a recently discovered anomalously rapid decrease of the orbital
period was taken into account. We showed that the observed decrease can be
consistent with the magnetic stellar wind of the optical companion which
magnetic field was increased during the common envelope stage. Several
constraints on evolutionary scenario parameters were done.
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