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Stellar models typically use the mixing length approximation as a way to implement convection in a simplified manner. While conventionally the value of the mixing length parameter, $\alpha$, used is the solar calibrated value, many studies…

Solar and Stellar Astrophysics · Physics 2018-05-16 Lucas S. Viani , Sarbani Basu , Joel J. M. Ong , Ana Bonaca , William J. Chaplin

The temperatures and colors of stellar models are much less secure than predicted luminosities; consequently, it is important to ensure that the models which are used to interpret data for stellar populations satisfy existing observational…

Astrophysics · Physics 2007-05-23 Don A. VandenBerg

Benchmark stars are crucial as validating standards for current as well as future large stellar surveys of the Milky Way. However, the number of suitable metal-poor benchmarks is currently limited. We aim to construct a new set of…

Solar and Stellar Astrophysics · Physics 2020-08-05 I. Karovicova , T. R. White , T. Nordlander , L. Casagrande , M. Ireland , D. Huber , P. Jofré

We test our capability of deriving stellar physical parameters of giant stars by analysing a sample of field stars and the well studied open cluster IC 4651 with different spectroscopic methods. The use of a technique based on line-depth…

Aims: We investigate a new method to for obtaining the plasma parameters of solar prominences observed in the Mgii h&k spectral lines by comparing line profiles from the IRIS satellite to a bank of profiles computed with a one-dimensional…

Solar and Stellar Astrophysics · Physics 2021-09-01 Aaron W. Peat , Nicolas Labrosse , Brigitte Schmieder , Krzysztof Barczynski

Medium-resolution spectra from 3650 angstroms to 10,000 angstroms are presented for 96 giant H II regions distributed in 20 spiral galaxies. We have calculated two separate grids of photoionization models, adopting single-star atmospheres…

Astrophysics · Physics 2009-10-30 F. Bresolin , R. C. Kennicutt , D. R. Garnett

Gaia will obtain astrometry and spectrophotometry for essentially all sources in the sky down to a broad band magnitude limit of G=20, an expected yield of 10^9 stars. Its main scientific objective is to reveal the formation and evolution…

Instrumentation and Methods for Astrophysics · Physics 2015-06-05 C. Liu , C. A. L. Bailer-Jones , R. Sordo , A. Vallenari , R. Borrachero , X. Luri , P. Sartoretti

With the purpose of assessing classic spectroscopic methods on high-resolution and high signal-to-noise ratio spectra in the near-infrared wavelength region, we selected a sample of 65 F-, G-, and K-type stars observed with CARMENES, the…

By adopting the recently empirically derived dependence of $\alpha$-elements on $[\alpha/{\rm Fe}]$ instead of the conventionally applied uniform one, we tested the agreement between stellar model predictions and observations for red giant…

Solar and Stellar Astrophysics · Physics 2024-08-28 G. Valle , M. Dell'Omodarme , P. G. Prada Moroni , S. Degl'Innocenti

The metallicity dependence of the primary indices of the uvby photometric system for cooler dwarfs (Teff ~ 6500 K to 5000K) is investigated. The data base for the analysis is composed of the overlap between a composite catalog of selected,…

Astrophysics · Physics 2008-11-26 B. A. Twarog , L. C. Vargas , B. J. Anthony-Twarog

We present a grid of synthetic profiles of stellar H Balmer and HeI lines at optical wavelengths with a sampling of 0.3 A. The grid spans a range of effective temperature 4000 K < Teff < 50000 K, and gravity 0.0 < log g < 5.0 at solar…

Astrophysics · Physics 2009-10-31 Rosa M. Gonzalez Delgado , Claus Leitherer

(abridged) We explore in this paper the ability of spatially resolved spectroscopic measurements of the SZ effect (SZE) to determine the temperature profile of galaxy clusters. We derive a general formalism for the thermal SZE in galaxy…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 S. Colafrancesco , P. Marchegiani

We combine photometric and spectroscopic data on twelve modes excited in FG Vir to determine their spherical harmonic degrees, $\ell$, and to obtain constraints on the star model. The effective temperature consistent with the mean colours…

We rediscuss the temperature of O dwarfs based on new non-LTE line blanketed atmosphere models including stellar winds computed with the CMFGEN code of Hillier & Miller (1998). Compared to the latest calibration of Vacca et al. (1996), the…

Astrophysics · Physics 2010-04-29 F. Martins , D. Schaerer , D. J. Hillier

Extensive photoionization model grids are computed for single star HII regions using stellar atmosphere models from the WM-basic code. Mid-IR emission line intensities are predicted and diagnostic diagrams of [NeIII]/[NeII] and [SIV]/[SIII]…

Astrophysics · Physics 2009-11-10 C. Morisset

We present empirical calibrations that estimate stellar metallicity, effective temperature and surface gravity as a function of Lick/IDS indices. These calibrations have been derived from a training set of 261 stars for which (1)…

Astrophysics · Physics 2016-08-30 Sarah E. Robinson , Jay Strader , S. Mark Ammons , Gregory Laughlin , Debra Fischer

Galaxy clusters can be used as powerful cosmological probes, provided one can obtain accurate mass estimates, which requires a precise knowledge of the underlying astrophysics of galaxy clusters. For these purposes, spatially resolved…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-12 R. Wicker , M. De Petris , A. Ferragamo , I. Bartalucci , G. Yepes , E. Rasia , R. Adam , W. Cui , F. Mayet , L. Perotto , M. Muñoz-Echeverría

Optical Emission Spectroscopy is a widely used technique for plasma diagnosis, with particular interest in hydrogen atomic emission due to its prevalence in plasmas. However, accurately determining plasma parameters like electron density,…

Plasma Physics · Physics 2025-01-22 A. Sarsa , A. Jiménez-Solano , M. S. Dimitrijević , C. Yubero

Stellar models generally use simple parametrizations to treat convection. The most widely used parametrization is the so-called "Mixing Length Theory" where the convective eddy sizes are described using a single number, \alpha, the…

We present detailed parameter determinations of two chemically normal late A-type stars, HD 32115 and HD 37594, to uncover the reasons behind large discrepancies between two previous analyses of these stars performed with a semi-automatic…

Solar and Stellar Astrophysics · Physics 2015-05-28 L. Fossati , T. Ryabchikova , D. V. Shulyak , C. A. Haswell , A. Elmasli , C. P. Pandey , T. G. Barnes , K. Zwintz