Partially ionized hydrogen plasma in strong magnetic fields

Potekhin, A. Y.; Chabrier, G.; Shibanov, Yuri

doi:10.1103/physreve.60.2193

Cited by 69 publications

(113 citation statements)

References 69 publications

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“…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. The authors found that the change of the conduction treatment from Potekhin et al (1999) to Cassisi et al (2007) leads to a reduction of M He c by about 0.006 M with a corresponding decrease of TRGB luminosity of Δ log L/L ≈ 0.03 and of the ZAHB luminosity by Δ log L/L ≈ 0.02.…”

Section: Comparison With Recent Stellar Model Databasesmentioning

confidence: 99%

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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Section: Comparison With Recent Stellar Model Databasesmentioning

confidence: 99%

The Pisa Stellar Evolution Data Base for low-mass stars

Dell’Omodarme

Valle

Degl’Innocenti

et al. 2012

A&A

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“…In strong magnetic fields, however, the binding energies of atoms increase (for a review, Lai 2001; Potekhin, these proceedings; see also Fig. 7), and for temperatures and fields appropriate for INS, a fraction of up to 10% of neutral hydrogen will be present (Potekhin et al 1999). From initial model-atmosphere calculations that take the presence of neutral hydrogen into account , see their Fig.…”

Section: Hydrogenmentioning

confidence: 99%

Isolated neutron stars: magnetic fields, distances, and spectra

Kaplan¹,

Kerkwijk²

2007

Isolated Neutron Stars: From the Surface to the Interior

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We present timing measurements, astrometry, and high-resolution spectra of a number of nearby, thermally emitting, isolated neutron stars. We use these to infer magnetic field strengths and distances, but also encounter a number of puzzles. We discuss three specific ones in detail: (i) For RX J0720.4−3125 and RX J1308.6+2127, the characteristic ages are in excess of 1 Myr, while their temperatures and kinematic ages indicate that they are much younger; (ii) For RX J1856.5−3754, the brightness temperature for the optical emission is in excess of that measured at X-ray wavelengths for reasonable neutron-star radii; (iii) For RX J0720.4−3125, the spectrum changed from an initially featureless state to one with an absorption feature, yet there was only a relatively small change in T eff . Furthermore, we attempt to see whether the spectra of all seven sourced, in six of which absorption features have now been found, can be understood in the context of strongly magnetised hydrogen atmospheres. We find that the energies of the absorption features can be reproduced, but that the featureless spectra of some sources, especially the Wien-like high-energy tails, remain puzzling.

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“…near P ? (see Potekhin et al 1999), and we have used the fact that the oscillator strength is nonzero only when P ¼ P 0 (in the dipole approximation). The CM coupling effect will significantly smooth out the divergent behavior at !…”

Section: Analytic Model Of the Polarization Of Atomic Gas: Effect Of mentioning

confidence: 99%

“…In addition, because of the relatively high atmosphere density, a proper treatment should take account of the plasma nonideality that leads to Stark broadening and pressure ionization. Recently, thermodynamically consistent equations of state (EOSs) and opacities have been obtained for a magnetized, partially ionized H plasma for 8 ; 10 11 G P B 10 15 G (Potekhin et al 1999;, 2004. These EOSs and opacities have been implemented by for modeling NS atmospheres.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic Polarization in Partially Ionized Plasmas with Strong Magnetic Fields and Neutron Star Atmosphere Models

Potekhin

Lai

Chabrier

et al. 2004

ApJ

Self Cite

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The polarizability tensor of a strongly magnetized plasma and the polarization vectors and opacities of normal electromagnetic waves are studied for conditions typical of neutron star atmospheres, taking account of partial ionization effects. Vacuum polarization is also included, and a new set of fitting formulae are used that are accurate for wide range of field strengths. The full account of the coupling of the quantum mechanical structure of the atoms to their center-of-mass motion across the magnetic field is shown to be crucial for the correct evaluation of the polarization properties and opacities of the plasma. The self-consistent treatment of the polarizability and absorption coefficients proves to be necessary if the ionization degree of the plasma is low, which can occur in the atmospheres of cool or ultramagnetized neutron stars. Atmosphere models and spectra are presented to illustrate the importance of such self-consistent treatment.

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Partially ionized hydrogen plasma in strong magnetic fields

Cited by 69 publications

References 69 publications

The Pisa Stellar Evolution Data Base for low-mass stars

The Pisa Stellar Evolution Data Base for low-mass stars

Isolated neutron stars: magnetic fields, distances, and spectra

Electromagnetic Polarization in Partially Ionized Plasmas with Strong Magnetic Fields and Neutron Star Atmosphere Models

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