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In this contribution we present initial results of a study on convective boundary mixing (CBM) in massive stellar models using the GENEVA stellar evolution code. Before undertaking costly 3D hydrodynamic simulations, it is important to…

Solar and Stellar Astrophysics · Physics 2015-06-23 Andrea Cristini , Raphael Hirschi , Cyril Georgy , Casey Meakin , David Arnett , Maxime Viallet

We have performed a study of the orbital properties of seven eclipsing cataclysmic variable (CV) binary systems by analyzing photometric time series from the Transiting Exoplanet Survey Satellite (TESS). We employed Python code to determine…

Solar and Stellar Astrophysics · Physics 2025-01-22 Mennatalla Mahmoud Ellaqany , Valeria Garcia-Lopez , Emily S. Hatten , Mridul Agarwal , David A. Moffett

More than 20 pre-cataclysmic variable (pre-CV) systems have now been discovered with very short orbital periods ranging from 250 min down to 68 min. A pre-CV consists of a white dwarf or hot subdwarf primary and a low-mass companion star,…

Solar and Stellar Astrophysics · Physics 2018-10-24 L. Nelson , J. Schwab , M. Ristic , S. Rappaport

Although a large number of orbital periods of cataclysmic variable stars (CVs) have been measured, comparison of period and luminosity distributions with evolutionary theory is affected by strong selection effects. A test has been…

Astrophysics · Physics 2009-11-07 R. C. North , T. R. Marsh , U. Kolb , V. S. Dhillon , C. K. J. Moran

Using high-precision astrometric data from Gaia DR3 and updated systemic velocities from the literature, kinematical properties of cataclysmic variables (CVs) were investigated. By constraining the data according to the total space velocity…

Astrophysics of Galaxies · Physics 2024-12-11 R. Canbay , T. Ak , S. Bilir , F. Soydugan , Z. Eker

Context: Internal chemical mixing in intermediate- and high-mass stars represents an immense uncertainty in stellar evolution models.In addition to extending the main-sequence lifetime, chemical mixing also appreciably increases the mass of…

Solar and Stellar Astrophysics · Physics 2021-11-10 Cole Johnston

The evolution of the magnetism, winds and rotation of low-mass stars are all linked. One of the most common ways to probe the magnetic properties of low-mass stars is with the Zeeman-Doppler imaging (ZDI) technique. The magnetic properties…

Diffferentially rotating stars can support significantly more mass in equilibrium than nonrotating or uniformly rotating stars, according to general relativity. The remnant of a binary neutron star merger may give rise to such a…

Astrophysics · Physics 2009-10-31 Stuart L. Shapiro

We examine how tides, stellar evolution, and magnetic braking shape the rotation period (P$_{rot}$) evolution of low-mass stellar binaries up to orbital periods (P$_{orb}$) of 100 d across a wide range tidal dissipation parameters using two…

Solar and Stellar Astrophysics · Physics 2019-09-04 David P. Fleming , Rory Barnes , James R. A. Davenport , Rodrigo Luger

Strong selection effects are present in observational samples of cataclysmic variables (CVs), complicating comparisons to theoretical predictions. The selection criteria used to define most CV samples discriminate heavily against the…

Astrophysics · Physics 2009-11-13 Magaretha L. Pretorius , Christian Knigge

We present the photometric results of the eclipsing cataclysmic variable (CV) WZ Sge near the period minimum ($P_{min}$). Eight new mid-eclipse times were determined and the orbital ephemeris was updated. Our result shows that the orbital…

Astrophysics of Galaxies · Physics 2017-05-17 Z. -T. Han , S. -B. Qian , Irina Voloshina , L. -Y. Zhu

The existence of a stably stratified layer underneath the core-mantle boundary (CMB) has been recently revived by corroborating evidences coming from seismic studies, mineral physics and thermal evolution models. Such a layer could find its…

Geophysics · Physics 2020-06-24 Thomas Gastine , Julien Aubert , Alexandre Fournier

Hard X-ray surveys have proven remarkably efficient in detecting intermediate polars and asynchronous polars, two of the rarest type of cataclysmic variable (CV). Here we present a global study of hard X-ray selected intermediate polars and…

It has been shown that the rate of angular momentum loss (AML) in cataclysmic variables (CVs) below the period gap is about 2.47 times that caused by gravitational radiation, suggesting extra AML mechanism besides gravitational radiation.…

Solar and Stellar Astrophysics · Physics 2019-01-16 Wei-Min Liu , Xiang-Dong Li

We outline a mechanism that explains the observed lack of circumbinary planets (CBPs) via coupled stellar-tidal evolution of isolated binary stars. Tidal forces between low-mass, short-period binary stars on the pre-main sequence slow the…

Solar and Stellar Astrophysics · Physics 2018-05-23 David P. Fleming , Rory Barnes , David E. Graham , Rodrigo Luger , Thomas R. Quinn

It is predicted that half or more of all cataclysmic variables (CVs) should have evolved past the period minimum and now exist as so-called "period bouncers" where a white dwarf should be accreting from a Roche-lobe filling substellar…

The relative importance of different initiation mechanisms for coronal mass ejections (CMEs) on the Sun is uncertain. One possible mechanism is the loss of equilibrium of coronal magnetic flux ropes formed gradually by large-scale surface…

Solar and Stellar Astrophysics · Physics 2014-11-20 A. R. Yeates , G. D. R. Attrill , Dibyendu Nandy , D. H. Mackay , P. C. H. Martens , A. A. van Ballegooijen

In recent years, observers have found that the fraction of M-stars demonstrating significant magnetic activity transitions sharply from roughly $10\%$ for main-sequence stars earlier (more massive) than spectral type M3.5 (0.35 M$_\odot$)…

Solar and Stellar Astrophysics · Physics 2020-04-23 Connor P. Bice , Juri Toomre

For moderate and slow rotation, magnetic activity of solar-like stars is observed to strongly depend on rotation. These observations do not yet have a solid explanation in terms of dynamo theory. We aim to find such an explanation by…

Solar and Stellar Astrophysics · Physics 2020-10-07 J. Warnecke , M. J. Käpylä

We suggest a new mechanism to account for the loss of angular momentum in binaries with non-conservative mass exchange. It is shown that in some cases the loss of matter can result in increase of the orbital angular momentum of a binary. If…