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The theoretical and observed populations of pre-cataclysmic variables (pre-CVs) are dominated by systems with low-mass white dwarfs (WDs), while the WD masses in CVs are typically high. In addition, the space density of CVs is found to be…

Solar and Stellar Astrophysics · Physics 2016-01-27 G. Nelemans , L. Siess , S. Repetto , S. Toonen , E. S. Phinney

Using a parameterised function for the mass loss at the base of the post-shock region, we have constructed a formulation for magnetically confined accretion flows which avoids singularities, such as the infinity in density, at the base…

Astrophysics · Physics 2009-11-06 Kinwah Wu , Mark Cropper

We study some general properties of accretion disc variability in the context of stationary random processes. In particular, we are interested in mathematical constraints that can be imposed on the functional form of the Fourier…

High Energy Astrophysical Phenomena · Physics 2013-08-01 Tomas Pechacek , Rene W. Goosmann , Vladimir Karas , Bozena Czerny , Michal Dovciak

Aims: We investigate the evolution of protoplanetary discs (PPDs hereafter) with magnetically driven disc winds and viscous heating. Methods: We consider an initially massive disc with ~0.1 Msun to track the evolution from the early stage…

Earth and Planetary Astrophysics · Physics 2016-12-07 Takeru K. Suzuki , Masahiro Ogihara , Alessandro Morbidelli , Aurélien Crida , Tristan Guillot

The vertical structure of stationary thin accretion discs is calculated from the energy balance equation with heat generation due to microscopic ion viscosity {\eta} and electron heat conductivity {\kappa}, both depending on temperature. In…

High Energy Astrophysical Phenomena · Physics 2017-02-09 K. L. Malanchev , K. A. Postnov , N. I. Shakura

We extend our models of the vertical structure and emergent radiation field of accretion disks around supermassive black holes described in previous papers of this series. Our models now include both a self-consistent treatment of Compton…

Astrophysics · Physics 2009-11-06 Ivan Hubeny , Omer Blaes , Julian H. Krolik , E. Agol

$Aims.$ We present a database of 43,340 atmospheric models ($\sim$80,000 models at the conclusion of the project) for stars with stellar masses between 9 and 120 $M_{\odot}$, covering the region of the OB main-sequence and Wolf-Rayet (W-R)…

Solar and Stellar Astrophysics · Physics 2020-11-18 J. Zsargo , C. R. Fierro-Santillan , J. Klapp , A. Arrieta , L. Arias , J. M. Valencia , L. Di G. Sigalotti , M. Hareter , R. E. Puebla

We analyze the wavelength-dependent variability of a sample of spectroscopically confirmed active galactic nuclei (AGN) selected from near-UV ($NUV$) variable sources in the GALEX Time Domain Survey that have a large amplitude of optical…

High Energy Astrophysical Phenomena · Physics 2016-12-28 T. Hung , S. Gezari , D. O. Jones , R. P. Kirshner , R. Chornock , E. Berger , A. Rest , M. Huber , G. Narayan , D. Scolnic , C. Waters , R. Wainscoat , D. C. Martin , K. Forster , J. D. Neill

We study the dynamical effects of gravitational focusing by a binary companion on winds from late-type stars. In particular, we investigate the mass transfer and formation of accretion disks around the secondary in detached systems…

Solar and Stellar Astrophysics · Physics 2009-07-22 M. de Val-Borro , M. Karovska , D. Sasselov

We performed 3D MHD calculations of stream accretion in cataclysmic variable stars for which the white dwarf primary star possesses a strong and complex magnetic field. These calculations are motivated by observations of polars; cataclysmic…

High Energy Astrophysical Phenomena · Physics 2012-10-16 A. G. Zhilkin , D. V. Bisikalo , P. A. Mason

The accretion process in a typical S-type symbiotic star, targeting~AG Draconis, is investigated through 3D hydrodynamical simulations using the FLASH code. Regardless of the wind velocity of the giant star, an accretion disk surrounding…

Solar and Stellar Astrophysics · Physics 2022-06-15 Young-Min Lee , Hyosun Kim , Hee-Won Lee

We investigate the structure and evolution of a geometrically thin viscous Keplerian circumbinary (CB) disk, using detailed models of their radiative/convective vertical structure. We use a simplified description for the evolution of the…

Astrophysics · Physics 2009-11-07 G. Dubus , R. E. Taam , H. C. Spruit

The removal of angular momentum from protostellar systems drives accretion onto the central star and may drive the dispersal of the protoplanetary disk. Winds and jets can contribute to removing angular momentum from the disk, though the…

We compare accretion shock models with optical and ultraviolet spectra of pre-main sequence stars to (1) make the first determinations of accretion rates in intermediate mass T Tauri stars from continuum emission, and (2) derive improved…

Astrophysics · Physics 2009-10-31 Erik Gullbring , Nuria Calvet , James Muzerolle , Lee Hartmann

In this chapter we consider the processes which can lead to X-ray emission from different types of cataclysmic variable stars (CVs). CVs are semi-detached, binary star systems where material is transferred from the donor star (also known as…

High Energy Astrophysical Phenomena · Physics 2023-04-05 K. L. Page , A. W. Shaw

Wind-driven outflows are observed around a broad range of accreting objects throughout the Universe, ranging from forming low-mass stars to super-massive black holes. We study the interaction between a central isotropic wind and an…

Solar and Stellar Astrophysics · Physics 2020-09-02 Lichen Liang , Doug Johnstone , Sylvie Cabrit , Lars E. Kristensen

We review the most decisive currently available measurements of the surface effective temperatures, Teff, of white dwarf (WD) primaries in cataclysmic variables (CVs) during accretion quiescence, and use these as a diagnostic for their time…

Astrophysics · Physics 2011-02-11 Dean M. Townsley , Boris T. Gaensicke

The planet-forming region of protoplanetary disks is cold, dense, and therefore weakly ionized. For this reason, magnetohydrodynamic (MHD) turbulence is thought to be mostly absent, and another mechanism has to be found to explain gas…

Earth and Planetary Astrophysics · Physics 2017-04-05 William Béthune , Geoffroy Lesur , Jonathan Ferreira

We want to test if self-similar magneto-hydrodynamic (MHD) accretion-ejection models can explain the observational results for accretion disk winds in BHBs. In our models, the density at the base of the outflow, from the accretion disk, is…

High Energy Astrophysical Phenomena · Physics 2016-05-25 S. Chakravorty , P-O. Petrucci , J. Ferreira , G. Henri , R. Belmont , M. Clavel , S. Corbel , J. Rodriguez , M. Coriat , S. Drappeau , J. Malzac

Non-magnetic Cataclysmic Variables (CVs) show two distinct X-ray components: a hard, optically thin component and a soft, optically thick, blackbody-like component, both produced in the boundary layer between the accretion disk and the…

High Energy Astrophysical Phenomena · Physics 2026-02-27 Nazma Islam , Koji Mukai , Maurice A. Leutenegger , Gabriel W. Pratt