Thermal Conduction by Electrons in Stellar Matter

Hubbard, W. B.; Lampe, Mártin

doi:10.1086/190192

Cited by 239 publications

(184 citation statements)

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“…We employ the radiative opacities of Iglesias & Rogers (1996), which we interpolated in tables as function of density, temperature, and chemical element mass fractions, including carbon and oxygen. For the electron conduction opacity, we follow Hubbard & Lampe (1969) in the non-relativistic case, and Canuto (1970) in the relativistic case. The stellar models are computed using extended nuclear networks (Heger et al 2000).…”

Section: Binary Stellar Evolution Code and Initial Parameter Spacementioning

confidence: 99%

Ultra-stripped supernovae: progenitors and fate

Tauris¹,

Langer²,

Podsiadlowski³

2015

Monthly Notices of the Royal Astronomical Society

417

613

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The explosion of ultra-stripped stars in close binaries can lead to ejecta masses < 0.1 M ⊙ and may explain some of the recent discoveries of weak and fast optical transients. In Tau ris et al. (2013), it was demonstrated that helium star companions to neutron stars (NSs) may experience mass transfer and evolve into naked ∼ 1.5 M ⊙ metal cores, barely above the Chandrasekhar mass limit. Here we elaborate on this work and present a systematic investigation of the progenitor evolution leading to ultra-stripped supernovae (SNe). In particular, we examine the binary parameter space leading to electron-capture (EC SNe) and iron core-collapse SNe (Fe CCSNe), respectively, and determine the amount of helium ejected with applications to their observational classification as Type Ib or Type Ic. We mainly evolve systems where the SN progenitors are helium star donors of initial mass M He = 2.5 − 3.5 M ⊙ in tight binaries with orbital periods of P orb = 0.06 − 2.0 days, and hosting an accreting NS, but we also discuss the evolution of wider systems and of both more massive and lighter -as well as single -helium stars. In some cases we are able to follow the evolution until the onset of silicon burning, just a few days prior to the SN explosion. We find that ultra-stripped SNe are possible for both EC SNe and Fe CCSNe. EC SNe only occur for M He = 2.60 − 2.95 M ⊙ depending on P orb . The general outcome, however, is an Fe CCSN above this mass interval and an ONeMg or CO white dwarf for smaller masses. For the exploding stars, the amount of helium ejected is correlated with P orb -the tightest systems even having donors being stripped down to envelopes of less than 0.01 M ⊙ . We estimate the rise time of ultra-stripped SNe to be in the range 12 hr − 8 days, and light curve decay times between 1 and 50 days. A number of fitting formulae for our models are provided with applications to population synthesis. Ultrastripped SNe may produce NSs in the mass range 1.10 − 1.80 M ⊙ and are highly relevant for LIGO/VIRGO since most (possibly all) merging double NS systems have evolved through this phase. Finally, we discuss the low-velocity kicks which might be imparted on these resulting NSs at birth.

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Section: Binary Stellar Evolution Code and Initial Parameter Spacementioning

confidence: 99%

Ultra-stripped supernovae: progenitors and fate

Tauris¹,

Langer²,

Podsiadlowski³

2015

Monthly Notices of the Royal Astronomical Society

417

613

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“…Castellani & Degl'Innocenti 1999;Catelan et al 1996). Castellani & Degl'Innocenti (1999) noticed that the adoption of the Itoh et al (1983) evaluations, present in the STEV database, instead of the Hubbard & Lampe (1969) ones, adopted by the Dartmouth database, leads to an increase of the helium core of about 0.005 M and thus to a corresponding (1983) and Hubbard & Lampe (1969) ones, but closer to the Itoh et al (1983) results. In Cassisi et al (2007) the opacity calculations by Potekhin (1999) and Potekhin et al (1999) were improved by including the electron-electron scattering in partially degenerate and non degenerate matter.…”

Section: Comparison With Recent Stellar Model Databasesmentioning

confidence: 79%

The Pisa Stellar Evolution Data Base for low-mass stars

Dell’Omodarme

Valle

Degl’Innocenti

et al. 2012

A&A

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Context. The last decade showed an impressive observational effort from the photometric and spectroscopic point of view for ancient stellar clusters in our Galaxy and beyond, leading to important and sometimes surprising results. Aims. The theoretical interpretation of these new observational results requires updated evolutionary models and isochrones spanning a wide range of chemical composition so that the possibility of multipopulations inside a stellar cluster is also taken also into account. Methods. With this aim we built the new "Pisa Stellar Evolution Database" of stellar models and isochrones by adopting a welltested evolutionary code (FRANEC) implemented with updated physical and chemical inputs. In particular, our code adopts realistic atmosphere models and an updated equation of state, nuclear reaction rates and opacities calculated with recent solar elements mixture. Results. A total of 32 646 models have been computed in the range of initial masses 0.30 ÷ 1.10 M for a grid of 216 chemical compositions with the fractional metal abundance in mass, Z, ranging from 0.0001 to 0.01, and the original helium content, Y, from 0.25 to 0.42. Models were computed for both solar-scaled and α-enhanced abundances with different external convection efficiencies. Correspondingly, 9720 isochrones were computed in the age range 8÷15 Gyr, in time steps of 0.5 Gyr. The whole database is available to the scientific community on the web. Models and isochrones were compared with recent calculations available in the literature and with the color-magnitude diagram of selected Galactic globular clusters. The dependence of relevant evolutionary quantities, namely turn-off and horizontal branch luminosities, on the chemical composition and convection efficiency were analyzed in a quantitative statistical way and analytical formulations were made available for reader's convenience. These relations can be useful in several fields of stellar evolution, e.g. evolutionary properties of binary systems, synthetic models for simple stellar populations and for star counts in galaxies, and chemical evolution models of galaxies.

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“…The H, He, and C regions, as well as the lower boundary of surface convection, are marked. Hubbard & Lampe (1969) conduction opacities used as standard input in BaSTI calculations. As shown by Fig.…”

Section: Discussionmentioning

confidence: 99%

Comparison of theoretical white dwarf cooling timescales

Salaris

Althaus

Garcı́a–Berro

2013

A&A

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Context. An accurate assessment of white dwarf cooling times is paramount so that white dwarf cosmochronology of Galactic populations can be put on more solid grounds. This issue is particularly relevant in view of the enhanced observational capabilities provided by the next generation of extremely large telescopes, that will offer more avenues to use white dwarfs as probes of Galactic evolution and test-beds of fundamental physics. Aims. We estimate for the first time the consistency of results obtained from independent evolutionary codes for white dwarf models with fixed mass and chemical stratification, when the same input physics is employed in the calculations. Methods. We compute and compare cooling times obtained from two independent and widely used stellar evolution codes, BaSTI and LPCODE evolutionary codes, using exactly the same input physics for 0.55 M white dwarf models with both pure carbon and uniform carbon-oxygen (50/50 mass fractions) cores, and pure hydrogen layers with mass fraction q H = 10 −4 M WD on top of pure helium buffers of mass q He = 10 −2 M WD . Results. Using the same radiative and conductive opacities, photospheric boundary conditions, neutrino energy loss rates, and equation of state, cooling times from the two codes agree within ∼2% at all luminosities, except when log(L/L ) > −1.5 where differences up to ∼8% do appear, because of the different thermal structures of the first white dwarf converged models at the beginning of the cooling sequence. This agreement is true for both pure carbon and uniform carbon-oxygen stratification core models, and also when the release of latent heat and carbon-oxygen phase separation are considered. We have also determined quantitatively and explained the effect of varying equation of state, low-temperature radiative opacities, and electron conduction opacities in our calculations, Conclusions. We have assessed for the first time the maximum possible accuracy in the current estimates of white dwarf cooling times, resulting only from the different implementations of the stellar evolution equations and homogeneous input physics in two independent stellar evolution codes. This accuracy amounts to ∼2% at luminosities lower than log (L/L ) ∼ −1.5. This difference is smaller than the uncertainties in cooling times attributable to the present uncertainties in the white dwarf chemical stratification. Finally, we extend the scope of our work by providing tabulations of our cooling sequences and the required input physics that can be used as a comparison test of cooling times obtained from other white dwarf evolutionary codes.

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Thermal Conduction by Electrons in Stellar Matter

Cited by 239 publications

References 0 publications

Ultra-stripped supernovae: progenitors and fate

Ultra-stripped supernovae: progenitors and fate

The Pisa Stellar Evolution Data Base for low-mass stars

Comparison of theoretical white dwarf cooling timescales

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