Full evolution of low-mass white dwarfs with helium and oxygen cores

Panei, J. A.; Althaus, Leandro Gabriel; Chen, X.; Han, Zhanwen

doi:10.1111/j.1365-2966.2007.12400.x

Cited by 163 publications

(292 citation statements)

References 45 publications

Supporting

Mentioning

271

Contrasting

Unclassified

Order By: Relevance

“…This contrasts with the situation for the least massive ELM sequences, where nuclear burning substantially delays their evolution by several Gyr at higher effective temperatures. This age dichotomy, which results from the interplay of element diffusion and nuclear burning during the flash episodes, is a remarkable property of very lowmass He-core white dwarfs with important observational consequences, as we reported in previous investigations (see Althaus et al 2001;Panei et al 2007, and references therein).…”

Section: Evolutionary Resultsmentioning

confidence: 67%

“…Because of the very low stellar mass values that characterize these ELM white dwarfs (lower than about 0.20 M 1 ), they are believed to be the result of compact binary evolution, during which the envelope of a red giant star is removed before the core reaches enough mass to ignite helium. The evolution of He-core white dwarfs has been studied by Driebe et al (1998), Sarna et al (2000), Althaus et al (2001), Serenelli et al (2002), Nelson et al (2004), Benvenuto & De Vito (2005), Panei et al (2007), and more recently by Gautschy (2013).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

New evolutionary sequences for extremely low-mass white dwarfs

Althaus

Bertolami

Córsico

2013

A&A

256

475

View full text Add to dashboard Cite

Context. The number of detected extremely low-mass (ELM) white dwarf stars has increased drastically in recent years, thanks to the results of many surveys. In addition, some of these stars have been found to exhibit pulsations, making them potential targets for asteroseismology. Aims. We provide a fine and homogeneous grid of evolutionary sequences for helium (He) core white dwarfs for the whole range of their expected masses (0.15 M * /M 0.45), including the mass range for ELM white dwarfs (M * /M 0.20). The grid is appropriate for mass and age determination of these stars, as well as for studying their adiatabic pulsational properties. Methods. White dwarf sequences have been computed by performing full evolutionary calculations that consider the main energy sources and processes of chemical abundance changes during white dwarf evolution. Realistic initial models for the evolving white dwarfs have been obtained by computing the nonconservative evolution of a binary system consisting of an initially 1 M ZAMS star and a 1.4 M neutron star for various initial orbital periods. To derive cooling ages and masses for He-core white dwarfs, we perform a least square fitting of the M(T eff , g) and Age(T eff , g) relations provided by our sequences by using a scheme that takes into account the time spent by models in different regions of the T eff − g plane. This is particularly useful when multiple solutions for cooling age and mass determinations are possible in the case of CNO-flashing sequences. We also explore in a preliminary way the adiabatic pulsational properties of models near the critical mass for the development of CNO flashes (∼0.2 M ). This is motivated by the discovery of pulsating white dwarfs with stellar masses near this threshold value. Results. We obtain reliable and homogeneous mass and cooling age determinations for 58 very low-mass white dwarfs, including three pulsating stars. Also, we find substantial differences in the period spacing distributions of g-modes for models with stellar masses near ∼0.2 M , which could be used as a seismic tool to distinguish stars that have undergone CNO flashes in their early cooling phase from those that have not. Finally, for an easy application of our results, we provide a reduced grid of values useful to obtain the masses and ages of He-core white dwarfs.

show abstract

Section: Evolutionary Resultsmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

New evolutionary sequences for extremely low-mass white dwarfs

Althaus

Bertolami

Córsico

2013

A&A

256

475

View full text Add to dashboard Cite

show abstract

“…These white dwarfs are probably the result of mass transfer in close binary systems (Sarna et al 2000), since exceedingly high ages would be needed to produce very low-mass white dwarfs through single-star evolution. However, we have not modeled the binary evolution leading to the formation of these stars, as done in Panei et al (2007). It is worth mentioning in this context that, after the termination of the mass-loss episodes, the subsequent evolution of the model does not depend on the details of how most of the envelope was lost.…”

Section: Initial Modelsmentioning

confidence: 99%

Evolution and colors of helium-core white dwarf stars with high-metallicity progenitors

Althaus

Panei

Romero

et al. 2009

A&A

Self Cite

View full text Add to dashboard Cite

Aims. Motivated by the recent detection of single and binary He-core white dwarfs in metal-rich clusters, we present a full set of evolutionary calculations and colors appropriate to the study of these white dwarfs. The paper is also aimed at investigating whether stable hydrogen burning may constitute a major source of energy for massive He-core white dwarfs resulting from high-metallicity progenitors. Methods. White dwarf sequences are derived by considering the evolutionary history of progenitor stars with supersolar metallicities. We also incorporate a self-consistent, time-dependent treatment of gravitational settling and chemical diffusion, as well as of the residual nuclear burning. Results. We find that the influence of residual nuclear burning during the late stages of white dwarf evolution is strongly dependent on the chemical diffusion at the base of the hydrogen-rich envelope. When no diffusion is considered, residual hydrogen burning strongly influences the advanced stages of white dwarf cooling, introducing evolutionary delays of several Gyr. By contrast, when diffusion is taken into account, the role of residual nuclear burning is strongly mitigated, and the evolution is only dictated by the thermal content stored in the ions. In addition, for all of our sequences, we provide accurate color and magnitudes on the basis of new and improved non-gray model atmospheres that explicitly include Lyα quasi-molecular opacity.

show abstract

“…Also shown as black points are other direct mass-radius measurements from eclipsing PCEB systems (O'Brien et al 2001;Pyrzas et al 2012;Parsons et al 2010aParsons et al , 2012aBours et al 2014Bours et al , 2015. Theoretical mass-radius relationships for carbon-oxygen core white dwarfs are shown in grey (Benvenuto & Althaus 1999) and helium core white dwarfs in blue (Panei et al 2007), labelled by temperature in thousands of Kelvin and for hydrogen envelope thicknesses of M H /M WD = 10 −4 . Inset we show a zoom of the measured QS Vir parameters with a theoretical mass-radius relationship for a 14,200K white dwarf with a thick hydrogen envelope (M H /M WD = 10 −4 , solid line) and a thin envelope (M H /M WD = 10 −6 , dashed line), showing that the measured parameters are in excellent agreement with the theoretical models for a white dwarf with a thick hydrogen envelope.…”

Section: Modelling the Eclipse Light Curvementioning

confidence: 99%

The crowded magnetosphere of the post-common-envelope binary QS Virginis

Parsons

Hill

Marsh

et al. 2016

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

We present high speed photometry and high resolution spectroscopy of the eclipsing post common envelope binary QS Virginis (QS Vir). Our UVES spectra span multiple orbits over more than a year and reveal the presence of several large prominences passing in front of both the M star and its white dwarf companion, allowing us to triangulate their positions. Despite showing small variations on a timescale of days, they persist for more than a year and may last decades. One large prominence extends almost three stellar radii from the M star. Roche tomography reveals that the M star is heavily spotted and that these spots are longlived and in relatively fixed locations, preferentially found on the hemisphere facing the white dwarf. We also determine precise binary and physical parameters for the system. We find that the 14, 220 ± 350 K white dwarf is relatively massive, 0.782 ± 0.013M ⊙ , and has a radius of 0.01068 ± 0.00007R ⊙ , consistent with evolutionary models. The tidally distorted M star has a mass of 0.382 ± 0.006M ⊙ and a radius of 0.381 ± 0.003R ⊙ , also consistent with evolutionary models. We find that the magnesium absorption line from the white dwarf is broader than expected. This could be due to rotation (implying a spin period of only ∼700 seconds), or due to a weak (∼100kG) magnetic field, we favour the latter interpretation. Since the M star's radius is still within its Roche lobe and there is no evidence that its over-inflated we conclude that QS Vir is most likely a pre-cataclysmic binary just about to become semi-detached.

show abstract

Full evolution of low-mass white dwarfs with helium and oxygen cores

Cited by 163 publications

References 45 publications

New evolutionary sequences for extremely low-mass white dwarfs

New evolutionary sequences for extremely low-mass white dwarfs

Evolution and colors of helium-core white dwarf stars with high-metallicity progenitors

The crowded magnetosphere of the post-common-envelope binary QS Virginis

Contact Info

Product

Resources

About