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We compute a new generation of standard solar models (SSMs) that includes recent updates on some important nuclear reaction rates and a more consistent treatment of the equation of state. Models also include a novel and flexible treatment…

We investigate the effect of helium abundance and $\alpha$-element enhancement on the properties of convection in envelopes of solar-like main-sequence stars stars using a grid of 3D radiation hydrodynamic simulations. Helium abundance…

Solar and Stellar Astrophysics · Physics 2015-06-17 Joel D. Tanner , Sarbani Basu , Pierre Demarque

Context. Europium is an almost pure r-process element, which may be useful as a reference in nucleocosmochronology. Aims. To determine the photospheric solar abundance using CO5BOLD 3-D hydrodynamical model atmospheres. Methods. Disc-centre…

Astrophysics · Physics 2009-11-13 A. Mucciarelli , E. Caffau , B. Freytag , H. -G. Ludwig , P. Bonifacio

The revision of the standard Los Alamos opacities in the 1980-1990s by a group from the Lawrence Livermore National Laboratory (OPAL) and the Opacity Project (OP) consortium was an early example of collaborative big-data science, leading to…

Solar and Stellar Astrophysics · Physics 2018-05-22 Claudio Mendoza

The purpose of this work is to better understand the confidence limits of the photospheric solar oxygen abundance derived from three-dimensional models using the forbidden [OI] line at 6300 \AA , including correlations with other parameters…

Solar and Stellar Astrophysics · Physics 2017-03-29 M. Cubas Armas , A. Asensio Ramos , H. Socas-Navarro

The Sun is the most studied of stars and a laboratory of fundamental physics. However, the understanding of our star is stained by the solar modelling problem which can stem from various causes. We combine inversions of sound speed, an…

Solar and Stellar Astrophysics · Physics 2019-02-28 G. Buldgen , S. J. A. J. Salmon , A. Noels , V. A. Baturin , P. Eggenberger , G. Meynet , A. Miglio

The chemical composition of the Sun is requested in the context of various studies in astrophysics, among them in the calculation of the standard solar models (SSMs), which describe the evolution of the Sun from the pre-main-sequence to its…

In an effort to estimate the largely unknown effects of photospheric temperature fluctuations on spectroscopic abundance determinations, we have studied the problem of LTE line formation in the inhomogeneous solar photosphere based on…

Astrophysics · Physics 2009-11-07 M. Steffen , H. Holweger

The chemical composition of the Sun is a fundamental yardstick in astronomy, relative to which essentially all cosmic objects are referenced. We reassess the solar abundances of all 83 long-lived elements, using highly realistic solar…

Solar and Stellar Astrophysics · Physics 2021-09-29 M. Asplund , A. M. Amarsi , N. Grevesse

Motivated by the controversy over the surface metallicity of the Sun, we present a re-analysis of the solar photospheric oxygen (O) abundance. New atomic models of O and Ni are used to perform Non-Local Thermodynamic Equilibrium (NLTE)…

The literature on precision differential abundances (PDAs) in stars is extensive. Surveys include sun-like stars in the solar neighborhood, binary systems, and Galactic clusters. Numerous references as well as a discussion of relevant…

Solar and Stellar Astrophysics · Physics 2021-03-03 Charles R. Cowley , Donald J. Bord , Kutluay Yuce

Solar X-ray spectra from the RESIK crystal spectrometer on the {\em CORONAS-F} spacecraft (spectral range $3.3-6.1$~\AA) are analyzed for thirty-three flares using a method to derive abundances of Si, S, Ar, and K, emission lines of which…

Solar and Stellar Astrophysics · Physics 2015-05-27 B. Sylwester , K. J. H. Phillips , J. Sylwester , A. Kepa

Current standard solar models neither account properly for the photospheric lithium abundance nor reproduce the inferred solar sound speed profile. Diffusive overshooting at the base of the solar convective envelope has previously been…

Solar and Stellar Astrophysics · Physics 2018-10-23 Andreas Christ Sølvsten Jørgensen , Achim Weiss

The new solar composition, when applied to compute a model of the Sun, leads to serious disagreement between the predictions of the model and the observations obtained by helioseismology. New measurements of the coronal Ne/O abundance ratio…

Astrophysics · Physics 2007-05-23 M. Asplund , N. Grevesse , M. Guedel , A. J. Sauval

Recent improvements in the modeling of solar convection and line formation led to downward revisions of the solar photospheric abundances of the lighter elements, which in turn led to changes in the radiative opacity of the solar interior…

Astrophysics · Physics 2009-11-11 C. Liefke , J. H. M. M. Schmitt

In this work, we present a photospheric solar silicon abundance derived using CO5BOLD model atmospheres and the LINFOR3D spectral synthesis code. Previous works have differed in their choice of a spectral line sample and model atmosphere as…

Solar and Stellar Astrophysics · Physics 2022-12-16 S. A. Deshmukh , H. -G. Ludwig , A. Kučinskas , M. Steffen , P. S. Barklem , E. Caffau , V. Dobrovolskas , P. Bonifacio

Stellar seismology appears more and more as a powerful tool for a better determination of the fundamental properties of solar-type stars. However the particular case of Sun is still challenging. The helioseismic sound speed determination…

We provide a grid of PHOENIX spectra of red giant and supergiant stars, that extend through optical and near-IR wavelengths. For the first time, models are also provided with modified surface abundances of C, N and O, as a step towards…

Astrophysics · Physics 2009-11-13 A. Lançon , P. H. Hauschildt , D. Ladjal , M. Mouhcine

Context: The stable element hafnium (Hf) and the radioactive element thorium (Th) were recently suggested as a suitable pair for radioactive dating of stars. The applicability of this elemental pair needs to be established for stellar…

Astrophysics · Physics 2009-11-13 Elisabetta Caffau , L. Sbordone , H. -G. Ludwig , P. Bonifacio , M. Steffen , N. T. Behara

We present an attempt to reconcile the solar tachocline glitch, a thin layer immediately beneath the convection zone in which the seismically inferred sound speed in the Sun exceeds corresponding values in standard solar models, with a…

Solar and Stellar Astrophysics · Physics 2018-04-04 J. Christensen-Dalsgaard , D. O. Gough , E. Knudstrup
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