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The observed evolution of the broad-band spectral energy distribution (SED) in NS X-ray Nova Aql X-1 during the rise phase of a bright FRED-type outburst in 2013 can be understood in the framework of thermal emission from unstationary…

We present a 904-1183 A spectrum of the dwarf nova VW Hydri taken with the Far Ultraviolet Spectroscopic Explorer during quiescence, eleven days after a normal outburst, when the underlying white dwarf accreter is clearly exposed in the far…

The evolution of protoplanetary discs has a substantial impact on theories of planet formation. To date, neither of the two main competing evolutionary models, namely the viscous-photoevaporative paradigm and the MHD winds model, has been…

In this paper we present high time-resolution observations of GW Librae and SDSS J161033.64-010223.3 -- two cataclysmic variables which have shown periodic variations attributed to non-radial pulsations of the white dwarf. We observed both…

Observations of accreting systems often show significant variability (10-20 percent of accretion luminosity) on timescales much longer than expected for the disc regions releasing most of the luminosity. We propose an explicit physical…

Astrophysics · Physics 2009-11-10 A. R. King , J. E. Pringle , R. G. West , M. Livio

The stochastic variability (flickering) of the nova-like system (subclass of cataclysmic variable) MV Lyr yields a complicated power density spectrum with four break frequencies. Scaringi et al. (2012) analysed high-cadence Kepler data of…

Solar and Stellar Astrophysics · Physics 2015-06-23 A. Dobrotka , S. Mineshige , J. -U. Ness

We follow the changes in the structure of the accretion disk of the dwarf nova V2051 Oph along two separate outbursts in order to investigate the causes of its recurrent outbursts. We apply eclipse mapping techniques to a set of light…

Astrophysics · Physics 2009-06-23 R. Baptista , R. F. Santos , M. Faundez-Abans , A. Bortoletto

We construct time-dependent one-dimensional (vertically averaged) models of accretion disks produced by the tidal disruption of a white dwarf (WD) by a binary neutron star (NS) companion. Nuclear reactions in the disk midplane burn the WD…

High Energy Astrophysical Phenomena · Physics 2016-09-16 Ben Margalit , Brian D. Metzger

We present high-time-resolution photometry and phase-resolved spectroscopy of the short-period ($P_\mathrm{orb} = 80.52\,\mathrm{min}$) cataclysmic variable SDSS J123813.73-033933.0, observed with the $\mathit{Hubble}$ $\mathit{Space}$…

We present RXTE observations covering six normal outbursts of the dwarf nova SU UMa, the prototype of its class. The outbursts showed consistent X-ray behaviour with the X-ray count rate dropping suddenly by a factor of our, and with…

High Energy Astrophysical Phenomena · Physics 2015-05-14 David J. Collins , Peter J. Wheatley

We use the Shaviv and Wehrse (1991) code to model the vertical structure and the emission properties of quiescent dwarf nova discs. We find that in the case of HT Cas the quiescent disc must be optically thin, in contradiction with the…

Astrophysics · Physics 2009-10-30 Irit Idan , Jean-Pierre Lasota , Jean-Marie Hameury , Giora Shaviv

We report the first observed outburst of the magnetic cataclysmic variable XY Ari. X-ray observations show a flux increase by an order of magnitude the day after the first signs of outburst. During the 5-d duration the X-ray spin pulse is…

Astrophysics · Physics 2015-06-24 Coel Hellier , Koji Mukai , A. P. Beardmore

The evolution of the magnetorotational instability (MRI) during the transition from outburst to quiescence in a dwarf nova disk is investigated using three-dimensional MHD simulations. The shearing box approximation is adopted for the…

Astrophysics · Physics 2009-11-07 Takayoshi Sano , James M. Stone

We present here the results of eight years of our near-simultaneous optical/near-infrared spectro-photometric monitoring of bonafide FUor candidate `V2493 Cyg' starting from 2013 September to 2021 June. During our optical monitoring period…

We propose a modified color-magnitude diagram for novae in outburst, i.e., $(B-V)_0$ versus $(M_V-2.5 \log f_{\rm s})$, where $f_{\rm s}$ is the timescaling factor of a (target) nova against a comparison (template) nova, $(B-V)_0$ is the…

Solar and Stellar Astrophysics · Physics 2019-03-06 Izumi Hachisu , Mariko Kato

We argue that the quiescent value of the viscosity parameter of the accretion disc in WZ Sge may be alpha_{cold}~0.01, in agreement with estimates of alpha_{cold} for other dwarf novae. Assuming the white dwarf in WZ Sge to be magnetic, we…

Astrophysics · Physics 2008-11-26 O. M. Matthews , R. Speith , G. A. Wynn , R. G. West

We present new observations of the rapid oscillations in the dwarf nova VW Hyi, made late in outburst. These dwarf nova oscillations (DNOs) increase in period until they reach 33 s, when a transition to a strong 1st harmonic and weak…

Astrophysics · Physics 2009-11-11 Brian Warner , Patrick A. Woudt

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 present time-resolved FUV spectra of the dwarf novae SS Cyg and WX Hyi in quiescence from observations using the Hopkins Ultraviolet Telescope on the Astro-1 and Astro-2 Space Shuttle missions and the Goddard High Resolution Spectrograph…

Astrophysical jets seem to occur in nearly all types of accreting objects: from supermassive black holes to young stellar objects. Based on X-ray binaries, a unified scenario describing the disc/jet coupling has evolved and extended to many…