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We have reconstructed the temperatures and surface densities in the quiescent accretion disc in HT Cas by performing a "Physical Parameter Eclipse Mapping" analysis of archival UBVR observations. Using a simple hydrogen slab model and…

Astrophysics · Physics 2009-11-07 Sonja Vrielmann , Frederic V. Hessman , Keith Horne

We report results of the eclipse mapping analysis of an ensemble of light curves of HT Cas. The fast response of the white dwarf to the increase in mass transfer rate, the expansion rate of the accretion disc at the same time, and the…

Solar and Stellar Astrophysics · Physics 2011-05-10 R. Baptista , B. Borges , V. Kolokotronis , O. Giannakis , C. J. Papadimitriou

Accreting white dwarfs in Cataclysmic variables (CVs) show short-period (tens of minutes) brightness variations that are consistent with non-radial oscillations similar to gravity (g) modes observed in isolated white dwarfs (WDs). GW…

Solar and Stellar Astrophysics · Physics 2023-07-19 Praphull Kumar , Dean M. Townsley

We present an analysis of CCD photometric observations of the eclipsing novalike cataclysmic variable DW UMa obtained in two different luminosity states: high and intermediate. The star presents eclipses with very different depth: ~1.2 mag…

Astrophysics · Physics 2009-11-10 V. Stanishev , Z. Kraicheva , H. M. J. Boffin , V. Genkov , C. Papadaki , S. Carpano

We fit outbursts of two X-ray novae (Nova Monocerotis 1975=A0620-00 and Nova Muscae GS 1991=1124-683) using a time-dependent accretion disk model. The model is based on a new solution for a diffusion-type equation for the non-steady-state…

High Energy Astrophysical Phenomena · Physics 2009-05-18 G. V. Lipunova , N. I. Shakura

The classical nova V2491 Cyg was once suggested to be a recurrent nova. We have broadly reproduced the light curve of V2491 Cyg by a nova outburst model on a cold $1.36~M_\odot$ white dwarf (WD), which strongly suggests that V2491 Cyg is a…

Solar and Stellar Astrophysics · Physics 2021-07-07 Mariko Kato , Hideyuki Saio , Izumi Hachisu

RS Ophiuchi is a recurrent nova system that experiences outbursts every ~20 years, implying accretion at a high rate onto a massive white dwarf. However, previous X-ray observations of the system in quiescence have detected only faint…

High Energy Astrophysical Phenomena · Physics 2015-05-28 Thomas Nelson , Koji Mukai , Marina Orio , Juan Luna , Jeno Sokoloski

I review models trying to explain dwarf-nova outbursts and soft X-ray transients. The disc-instability model for dwarf-novae is still in its preliminary state of development: its predictions depend very strongly on the unknown viscosity…

Astrophysics · Physics 2011-04-15 J. P. Lasota

Light curve analysis of decay phase of nova outburst are summarized. Nova duration is determined by the strong wind mass-loss which depends only on the white dwarf mass. Fast novae correspond very massive white dwarfs and very slow novae…

Astrophysics · Physics 2007-05-23 Mariko Kato

The Dwarf Nova Oscillations observed in Cataclysmic Variable (CV) stars are interpreted in the context of a Low Inertia Accretor model, in which accretion on to an equatorial belt of the white dwarf primary causes the belt to vary its…

Astrophysics · Physics 2009-11-07 Brian Warner , Patrick A. Woudt

Aims. We aim to characterize the properties of the inner companion of the S-type AGB star pi1 Gru and to identify plausible future evolutionary scenarios for this triple system. Methods. We observed pi1 Gru with ALMA and VLT/SPHERE. In…

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

Quasar microlensing effects make it possible to measure the accretion disc sizes around distant supermassive black holes that are still well beyond the spatial resolution of contemporary instrumentation. The sizes measured with this…

High Energy Astrophysical Phenomena · Physics 2017-04-05 Pavel Abolmasov

We reanalyse archival GINGA and ASCA X-ray data from SS Cyg in both quiescence and outburst, using multi-temperature plasma models for the continuum and line emission, together with their reflection from the X-ray illuminated white dwarf…

Astrophysics · Physics 2015-06-24 C. Done , J. P. Osborne

Steadily accreting white dwarfs (WDs) are efficient sources of ionization and thus, are able to create extended ionized nebulae in their vicinity. These nebulae represent ideal tools for the detection of accreting WDs, given that in most…

Solar and Stellar Astrophysics · Physics 2022-06-01 D. Souropanis , A. Chiotellis , P. Boumis , M. Chatzikos , S. Akras , L. Piersanti , A. J. Ruiter , G. J. Ferland

Novae are the observational manifestations of thermonuclear runaways on the surface of accreting white dwarfs (WDs). Although novae are an ubiquitous phenomenon, their properties at low metallicity are not well understood. Using the…

Solar and Stellar Astrophysics · Physics 2019-10-02 Hai-Liang Chen , T. E. Woods , L. R. Yungelson , Luciano Piersanti , M. Gilfanov , Zhanwen Han

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…

In our earlier Paper I we showed that the accretion disc radius of the dwarf nova HT Cas in its quiescent state has not changed significantly during many years of observations. It has remained consistently large, close to the tidal…

Solar and Stellar Astrophysics · Physics 2020-10-21 V. V. Neustroev , S. V. Zharikov

A classical nova occurs when material accreting onto the surface of a white dwarf in a close binary system ignites in a thermonuclear runaway. Complex structures observed in the ejecta at late stages could result from interactions with the…

A significant fraction of white dwarfs (WDs) are observed to be polluted with metals despite high surface gravities and short settling times. The current theoretical model for this pollution is accretion of rocky bodies delivered to the WD…

Earth and Planetary Astrophysics · Physics 2015-06-18 Shane F. N. Frewen , Brad M. S. Hansen