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We present spectroscopic observations of the quiescent black hole binary A0620-00 with the the 6.5-m Magellan Clay telescope at Las Campanas Observatory. We measure absorption-line radial velocities of the secondary and make the most…

Astrophysics · Physics 2009-11-13 J. Neilsen , D. Steeghs , S. D. Vrtilek

DQ Herculis (Nova Herculis 1934) is a deeply eclipsing cataclysmic variable containing a magnetic white dwarf primary. The accretion disk is thought to block our line of sight to the white dwarf at all orbital phases due to its extreme…

Astrophysics · Physics 2009-11-07 K. Mukai , M. Still , F. A. Ringwald

We propose a new method to reconstruct the structure of accretion disks in dwarf novae using multi-band light curves of early superhumps. Our model assumes that early superhumps are caused by the rotation effect of non-axisymmetrically…

Astrophysics of Galaxies · Physics 2015-06-04 M. Uemura , T. Kato , T. Ohshima , H. Maehara

We present a model of a viscously evolving accretion disc around a magnetized neutron star. The model features the varying outer radius of the hot ionized part of the disc due to cooling and the varying inner radius of the disc due to…

High Energy Astrophysical Phenomena · Physics 2021-12-16 Galina Lipunova , Konstantin Malanchev , Sergey Tsygankov , Nikolai Shakura , Andrei Tavleev , Dmitry Kolesnikov

We analysed the flickering of selected nova-like cataclysmic variables observed by the TESS satellite and XMM-Newton. We searched for break frequencies ($f_{\rm b}$) in the corresponding power density spectra (PDS), and for any long-term…

High Energy Astrophysical Phenomena · Physics 2025-10-06 Andrej Dobrotka , Jozef Magdolen , Martin Melicherčík

We present a model of the non-stationary $\alpha$-disk with account for the irradiation and the vertical convection in the outer accretion disk where hydrogen is partially ionized. We include the viscous energy generation in the mix-length…

High Energy Astrophysical Phenomena · Physics 2015-12-03 Konstantin Malanchev , Nikolai Shakura

A theoretical light curve for the 1999 outburst of U Scorpii is presented in order to obtain various physical parameters of the recurrent nova. Our U Sco model consists of a very massive white dwarf (WD) with an accretion disk and a…

Astrophysics · Physics 2009-10-31 Izumi Hachisu , Mariko Kato , Taichi Kato , Katsura Matsumoto

We show that the disc instability model can reproduce all the observed properties of Z Cam stars if the energy equation includes heating of the outer disc by the mass-transfer stream impact and by tidal torques and if the mass-transfer rate…

Astrophysics · Physics 2009-11-06 V. Buat-Menard , J. -M. Hameury , J. -P. Lasota

Using a recent Chandra ACIS observation of the eclipsing cataclysmic variable (CV) V1460 Her (2MASS J16211735+4412541) with a fast-rotating ($P_{\rm spin} = 38.9$~s) white dwarf, we estimated a flux $F_{0.5-7 {\rm keV}}^{\rm abs} = (1.9\pm…

Solar and Stellar Astrophysics · Physics 2025-01-08 Erik B. Monson , George G. Pavlov , Gordon P. Garmire

We model the evolution of the accretion disk of WZ Sagittae during the long quiescence. We find that the large amount of mass in the disk derived from the outburst luminosity is a severe constraint and demands values of $\alpha_c$ $\approx$…

Astrophysics · Physics 2007-05-23 E. Meyer-Hofmeister , F. Meyer , B. F. Liu

The disc instability model accounts well for most of the observed properties of dwarf novae and soft X-ray transients, but the rebrightenings, reflares, and echoes occurring at the end of outbursts or shortly after in WZ Sge stars or soft…

Solar and Stellar Astrophysics · Physics 2021-06-16 J. -M. Hameury , J. -P. Lasota

New deep VLA D array HI observations of the highly inclined nearby spiral galaxy NGC 2683 are presented. Archival C array data were processed and added to the new observations. To investigate the 3D structure of the atomic gas disk, we made…

Astrophysics of Galaxies · Physics 2016-02-17 B. Vollmer , F. Nehlig , R. Ibata

I review various phenomena associated with mass-accreting white dwarfs (WDs) in the view of supersoft X-ray sources. When the mass-accretion rate is low (\dot M_{acc} < a few \times 10^{-7} M_\sun yr^{-1}), hydrogen nuclear burning is…

Solar and Stellar Astrophysics · Physics 2015-05-14 Mariko Kato

Using the HST Fine Guidance Sensor, we have measured a high precision astrometric parallax of the cataclysmic variable EX Hydrae, pi=15.50+-0.29mas. From the wavelength-integrated accretion-induced energy flux, we derive a quiescent…

Astrophysics · Physics 2009-11-10 K. Beuermann , Th. E. Harrison , B. E. McArthur , G. F. Benedict , B. T. Gaensicke

We investigated the temporal and spectral features of $\gamma$ Cassiopeiae's X-ray emission within the context of the white dwarf accretion hypothesis. We find that the variabilities present in the X-ray data show two different signals, one…

We report the analysis of time-series of optical photometry of SDSS J0926+3624 collected with the Liverpool Robotic Telescope between 2012 February and March while the object was in quiescence. We combined our median eclipse timing with…

Solar and Stellar Astrophysics · Physics 2018-05-24 Wagner Schlindwein , Raymundo Baptista

V1674 Her is one of the fastest novae, of which the very early phase is well observed including optical rise to the peak over 10 magnitudes. We present a full theoretical light curve model of V1674 Her. Our $1.35~M_\odot$ white dwarf (WD)…

Solar and Stellar Astrophysics · Physics 2025-06-06 Mariko Kato , Izumi Hachisu , Hideyuki Saio

We analyse optical photometric data of short term variability (flickering) of the accreting white dwarf in the jet-ejecting symbiotic star MWC560. The observations are obtained in 17 nights during the period November 2011 - October 2019.…

Solar and Stellar Astrophysics · Physics 2020-07-15 R. K. Zamanov , S. Boeva , K. A. Stoyanov , G. Latev , B. Spassov , A. Kurtenkov , G. Nikolov

New eclipse timings of the Z Cam-type dwarf nova AY Psc were measured and the orbital ephemeris was revised. Based on the long-term AAVSO data, moreover, the outburst behaviors were also explored. Our analysis suggests that the normal…

Astrophysics of Galaxies · Physics 2017-06-14 Zhong-tao Han , Sheng-bang Qian , Irina Voloshina , Li-ying Zhu

Many high-state cataclysmic variables (CVs) exhibit blue-shifted absorption features in their ultraviolet (UV) spectra -- a smoking-gun signature of outflows. However, the impact of these outflows on {\em optical} spectra remains much more…

Solar and Stellar Astrophysics · Physics 2024-06-21 Yusuke Tampo , Christian Knigge , Knox S. Long , James H. Matthews , Noel Castro Segura