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We examine the angular momentum loss and associated rotational spin-down for magnetic hot stars with a line-driven stellar wind and a rotation-aligned dipole magnetic field. Our analysis here is based on our previous 2-D numerical MHD…

Astrophysics · Physics 2009-11-13 Asif ud-Doula , Stanley P. Owocki , Richard H. D. Townsend

The hot subdwarf HD 49798 has an X-ray emitting compact companion with a spin-period of 13.2 s and a dynamically measured mass of 1.28+/-0.05 M_sun, consistent with either a neutron star or a white dwarf. Using all the available XMM-Newton…

High Energy Astrophysical Phenomena · Physics 2016-03-23 Sandro Mereghetti , Fabio Pintore , Paolo Esposito , Nicola La Palombara , Andrea Tiengo , Gian Luca Israel , Luigi Stella

Magnetic fields generated by a dynamo mechanism due to differential rotation during stellar mergers are often proposed as an explanation for the presence of strong fields in certain classes of magnetic stars, including high field magnetic…

Solar and Stellar Astrophysics · Physics 2019-07-11 Gordon P. Briggs

This study investigates the conditions under which gravitational waves (GWs) are emitted during the merger of hot white dwarfs (WDs) in a binary system. Traditionally, these systems consist of two low-mass stars or a more massive WD paired…

Solar and Stellar Astrophysics · Physics 2025-01-14 Sílvia P. Nunes , José D. V. Arbañil , César H. Lenzi , Jaziel G. Coelho

Many magnetic white dwarfs exhibit a polarised spectrum that periodically varies as the star rotates because the magnetic field is not symmetric about the rotation axis. In this work, we report the discovery that while weakly magnetic white…

Solar and Stellar Astrophysics · Physics 2024-11-18 S. Bagnulo , J. D. Landstreet

We present a physical characterization of TMTS J00063798+3104160 (J0006), a rapidly rotating,ultra-massive white dwarf (WD) identified in high-cadence light curves from the Tsinghua University-Ma Huateng Telescope for Survey (TMTS). A…

It has been recently proposed that massive fast-rotating highly-magnetized white dwarfs could describe the observational properties of some of Soft Gamma-Ray Repeaters (SGRs) and Anomalous X-Ray Pulsars (AXPs). Moreover, it has also been…

Solar and Stellar Astrophysics · Physics 2014-03-28 J. A. Rueda , K. Boshkayev , L. Izzo , R. Ruffini , P. Loren Aguilar , B. Kulebi , G. Aznar Siguan , E. Garcia Berro

We have used a model of magnetic accretion to investigate the rotational equilibria of magnetic cataclysmic variables (mCVs). The results of our numerical simulations demonstrate that there is a range of parameter space in the P_spin /…

Astrophysics · Physics 2009-11-10 A. J. Norton , G. A. Wynn , R. V. Somerscales

We calculate the stellar evolution of both white dwarfs (WDs) in AM CVn binaries with orbital periods of $P_{\mathrm{orb}} \approx 5-70$ minutes. We focus on the cases where the donor starts as a $M_{\mathrm{He}} < 0.2 \, M_{\odot}$ Helium…

Solar and Stellar Astrophysics · Physics 2021-12-22 Tin Long Sunny Wong , Lars Bildsten

We study the evolution of the protoplanetary discs (PPDs) in the presence of magnetically driven winds with the stress relations motivated by the non-ideal MHD disc simulations. Contribution of the magnetic winds in the angular momentum…

Astrophysics of Galaxies · Physics 2019-07-31 Mohsen Shadmehri , Sayyedeh Masoumeh Ghoreyshi

Binaries of two white dwarfs (WDs) are an important class of astrophysical objects that are theorized to lead to Type Ia supernovae and are also used to gain insight into complex processes involved in stellar binary evolution. We report the…

Rotating magnetized white dwarfs are studied within the framework of general relativity using Hartle's formalism. Matter inside magnetized white dwarfs is described by an equation of state of particles under the action of a constant…

High Energy Astrophysical Phenomena · Physics 2019-02-18 Diana Alvear Terrero , Daryel Manreza Paret , Aurora Perez Martinez

A dynamo mechanism driven by differential rotation when stars merge has been proposed to explain the presence of strong fields in certain classes of magnetic stars. In the case of the high field magnetic white dwarfs (HFMWDs), the site of…

Solar and Stellar Astrophysics · Physics 2018-05-16 Gordon P. Briggs , Lilia Ferrario , Christopher A. Tout , Dayal T. Wickramasinghe

Low-mass white dwarfs (LMWDs) are believed to be exclusive products of binary evolution, as the Universe is not yet old enough to produce them from single stars. Because of the strong tidal forces operating during the binary interaction…

We present a detailed model atmosphere analysis of massive white dwarfs with $M > 0.9~M_\odot$ and $T_{\rm eff}\geq11,000$ K in the Montreal White Dwarf Database 100 pc sample and the Pan-STARRS footprint. We obtained follow-up optical…

During the growth of a cold dark matter halo, the direction of its spin can undergo rapid changes. These could disrupt or even destroy a stellar disc forming in the halo, possibly resulting in the generation of a bulge or spheroid. We…

Cosmology and Nongalactic Astrophysics · Physics 2016-07-07 Philip E. Bett , Carlos S. Frenk

We study numerically the so-called ``turn-over scenario'' for rotating magnetic white dwarfs and neutron stars. According to this scenario, the magnetic symmetry axis of the model inclines at a gradually increasing angle (the so-called…

Astrophysics · Physics 2007-05-23 V. S. Geroyannis

The evolution of binaries consisting of evolved main sequence stars (1 < M_d/Msun < 3.5) with white dwarf companions (0.7 < M_wd/Msun < 1.2) is investigated through the thermal mass transfer phase. Taking into account the stabilizing effect…

Astrophysics · Physics 2016-08-30 Natalia Ivanova , Ronald E. Taam

The magnetic white dwarf SDSS J121209.31+013627.7 exhibits a weak, narrow Halpha emission line whose radial velocity and strength are modulated on a period of ~90 minutes. Though indicative of irradiation on a nearby companion, no cool…

Astrophysics · Physics 2009-11-13 G. D. Schmidt , P. Szkody , N. M. Silvestri , M. C. Cushing , J. Liebert , P. S. Smith