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I review what we know about the donor stars in cataclysmic variables (CVs), focusing particularly on the close link between these binary components and the overall secular evolution of CVs. I begin with a brief overview of the "standard…

Solar and Stellar Astrophysics · Physics 2015-03-17 Christian Knigge

We present follow-up spectroscopy of 21 cataclysmic variables (CVs) with evolved secondaries and ongoing or recently-terminated mass transfer. Evolutionary models predict that the secondaries should have anomalous surface abundances owing…

Solar and Stellar Astrophysics · Physics 2023-07-05 Natsuko Yamaguchi , Kareem El-Badry , Antonio C. Rodriguez , Maude Gull , Benjamin R. Roulston , Zachary P. Vanderbosch

We investigate why the spectral type of most cataclysmic variable (CV) secondaries is significantly later than that of a ZAMS star with the same mean density. Using improved stellar input physics, tested against observations of low-mass…

Astrophysics · Physics 2015-06-24 I. Baraffe , U. Kolb

Secondary stars in cataclysmic variables (CVs) follow a well defined period-density relation. Thus, canonical donor stars in CVs are generally low-mass stars of spectral type M. However, several CVs have been observed containing secondary…

Solar and Stellar Astrophysics · Physics 2015-06-19 A. Rebassa-Mansergas , S. G. Parsons , C. M. Copperwheat , S. Justham , B. T. Gaensicke , M. R. Schreiber , T. R. Marsh , V. S. Dhillon

A substantial fraction of Cataclysmic Variables (CVs) reveals non-solar abundances. A comprehensive list of CVs which includes those that have been examined for these abundances is given. Three possible sources of these non-solar abundances…

Solar and Stellar Astrophysics · Physics 2021-06-23 Warren M. Sparks , Edward M. Sion

We present a new sample of $K$-band spectral observations for CVs: non-magnetic and magnetic as well as present day and pre CVs. The purpose of this diverse sample is to address the recent claim that the secondary stars in dwarf novae are…

Solar and Stellar Astrophysics · Physics 2015-05-18 Steve B. Howell , Thomas E. Harrison , Paula Szkody , Nicole M. Silvestri

We review the recent knowledge base pertaining to causes for mass accretion variations (high/low states) in highly magnetic cataclysmic variables (i.e. polars). We then examine what theory has to say about the properties of the secondary…

Astrophysics · Physics 2007-05-23 Steve B. Howell

The detection of heavy elements at suprasolar abundances in the atmospheres of some accreting white dwarfs in cataclysmic variables, coupled with the high temperatures needed to produce these elements requires explosive thermonuclear…

Solar and Stellar Astrophysics · Physics 2015-06-22 Edward M. Sion

We model cataclysmic variables (CVs) with solar metallicity donors ($X=0.7,\:Z=0.02$) that evolve to form AM CVn stars through the Evolved CV formation channel using various angular momentum loss mechanisms by magnetic braking…

Solar and Stellar Astrophysics · Physics 2023-02-02 Arnab Sarkar , Hongwei Ge , Christopher A. Tout

We derive metallicities for 41 cataclysmic variables (CVs) from near-infrared spectroscopy. We use synthetic spectra that cover the 0.8 $\mu$m $\leq \lambda \leq$ 2.5 $\mu$m bandpass to ascertain the value of [Fe/H] for CVs with K-type…

Solar and Stellar Astrophysics · Physics 2016-12-14 Thomas E. Harrison

We present measurements of the component masses in 15 Cataclysmic Variables (CVs) - 6 new estimates and 9 improved estimates. We provide new calibrations of the relationship between superhump period excess and mass ratio, and use this…

We present the results of a systematic study of cataclysmic variables (CVs) and related systems, combining detailed binary-population synthesis (BPS) models with a grid of 120 binary evolution sequences calculated with a Henyey-type stellar…

Astrophysics · Physics 2007-05-23 Ph. Podsiadlowski , Z. Han , S. Rappaport

We show that the secondaries in short-period cataclysmic variables with orbital periods $P < 3$ hr are close to the solar-abundance main sequence defined by single field stars. In cataclysmic variables with $P > 3$ hr, the earliest spectral…

Astrophysics · Physics 2007-05-23 K. Beuermann , I. Baraffe , U. Kolb , M. Weichhold

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 photometric ULTRACAM observations of three new short period cataclysmic variables, we model the primary eclipse lightcurves to extract the orbital separation, masses, and radii of their component stars. We find donor masses of 0.060…

Recent theoretical and observational progress has substantially improved the definition of the lower main sequence and established a new basis for a comparison of main sequence stars and the secondaries in CVs. The evolutionary sequences of…

Astrophysics · Physics 2009-10-31 K. Beuermann

We reconstruct the evolutionary path followed by cataclysmic variables (CVs) from the observed mass-radius relationship of their donor stars. Along the way, we update the semi-empirical CV donor sequence of Knigge (2006) and present a…

Solar and Stellar Astrophysics · Physics 2015-05-27 Christian Knigge , Isabelle Baraffe , Joseph Patterson

(Abridged) We present high-speed, three-colour photometry of seven short period (Porb <= 95 mins) eclipsing CVs from the Sloan Digital Sky Survey. We determine the system parameters via a parametrized model of the eclipse fitted to the…

In this paper we study the impact of chemically evolved secondaries on CV evolution. We find that when evolved secondaries are included a spread in the secondary mass-orbital period plane comparable to that seen in the data is produced for…

Astrophysics · Physics 2009-11-10 N. Andronov , M. H. Pinsonneault

We have carried out an extensive population synthesis study of the ensemble properties of the present-day population of cataclysmic variables (PDCVs) that takes into account the nuclear evolution of high-mass donors close to the bifurcation…

Solar and Stellar Astrophysics · Physics 2016-07-22 J. Goliasch , L. Nelson
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