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The temperature dependence of the symmetry energy and the symmetry free energy coefficients of atomic nuclei is investigated in a finite temperature Thomas-Fermi framework employing the subtraction procedure. A substantial decrement in the…

Nuclear Theory · Physics 2015-06-04 J. N. De , S. K. Samaddar

By comparing neutrino fluxes and central temperatures calculated from 1000 detailed numerical solar models, we derive improved scaling laws which show how each of the neutrino fluxes depends upon the central temperature (flux $\propto…

Astrophysics · Physics 2008-11-26 John N. Bahcall , Andrew Ulmer

Precise measurements of the fundamental properties of low-mass stars and brown dwarfs are key to understanding the physics underlying their formation and evolution. While there has been great progress over the last decade in studying the…

We present equivalent widths, improved model atmosphere parameters, and revised abundances for 14 species of 11 elements derived from high resolution optical spectroscopy of 311 metal-poor stars. All of these stars had their parameters…

Solar and Stellar Astrophysics · Physics 2025-02-27 Sanil Mittal , Ian U. Roederer

The thermal evolution of the energies and free energies of a set of spherical and near-spherical nuclei spanning the whole periodic table are calculated in the subtracted finite-temperature Thomas- Fermi framework with the zero-range…

Nuclear Theory · Physics 2015-06-11 J. N. De , S. K. Samaddar , B. K. Agrawal

We derive an empirical effective temperature and bolometric luminosity calibration for G and K dwarfs, by applying our own implementation of the InfraRed Flux Method to multi-band photometry. Our study is based on 104 stars for which we…

Astrophysics · Physics 2009-11-11 L. Casagrande , L. Portinari , C. Flynn

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

Photons are a penetrating probe of the hot medium formed in heavy-ion collisions, but they are emitted from all collision stages. At photon energies below 2-3 GeV, the measured photon spectra are approximately exponential and can be…

Nuclear Theory · Physics 2014-05-02 Chun Shen , Ulrich W. Heinz , Jean-Francois Paquet , Charles Gale

Deriving metallicities for solar-like stars follows well-established methods, but for cooler stars such as M dwarfs, the determination is much more complicated due to forests of molecular lines that are present. Several methods have been…

The temperature dependence of the integrated optical conductivity I(T) reflects the changes of the kinetic energy as spin and charge correlations develop. It provides a unique way to explore experimentally the kinetic properties of strongly…

Strongly Correlated Electrons · Physics 2009-11-07 Markus Aichhorn , Peter Horsch , Wolfgang von der Linden , Mario Cuoco

Precise fundamental atmospheric stellar parameters and abundance determination of individual elements in stars are important for all stellar population studies. Non-Local Thermodynamic Equilibrium (Non-LTE; hereafter NLTE) models are often…

Solar and Stellar Astrophysics · Physics 2023-03-15 Yangyang Li , Rana Ezzeddine

The time-dependent surface flux (t-SURFF) method is introduced for computing of strong-field infrared photo-ionization spectra of atoms by numerically solving the time-dependent Schr\"odinger equation on minimal simulation volumes. The…

Computational Physics · Physics 2015-05-30 Liang Tao , Armin Scrinzi

Stellar models applied to large stellar surveys of the Milky Way need to be properly tested against a sample of stars with highly reliable fundamental stellar parameters. We have established a program aiming to deliver such a sample. We…

Solar and Stellar Astrophysics · Physics 2022-02-09 I. Karovicova , T. R. White , T. Nordlander , L. Casagrande , M. Ireland , D. Huber

We present a sample of 32 stars of spectral types G and K, and luminosity classes I to V, with moderate activity levels, covering four orders of magnitude of surface gravity and a representative range of effective temperature. For each star…

Solar and Stellar Astrophysics · Physics 2024-12-18 F. Rosas-Portilla , K. -P. Schröder , D. Jack

In the spirit of multi-scale modelling magnetization dynamics at elevated temperature is often simulated in terms of a spin model where the model parameters are derived from first principles. While these parameters are mostly assumed…

Materials Science · Physics 2017-07-04 A. Deák , D. Hinzke , L. Szunyogh , U. Nowak

A number of empirical correlations that allows us to calculate the effective temperature and surface gravity for a set evolved post-AGB and RV Tauri stars are determined using as calibrators the intrinsic colours of 2MASS (Two Micron All…

Solar and Stellar Astrophysics · Physics 2012-01-16 R. E. Molina

We derive the stellar parameters of a sample of Galactic early-O type stars by analysing their UV and Far-UV spectra from FUSE (905-1187A), IUE, HST-STIS and ORFEUS (1200-2000A). The data have been modeled with spherical, hydrodynamic,…

Astrophysics · Physics 2009-11-10 Miriam Garcia , Luciana Bianchi

The high-temperature ratio (HTR) is a parameter quantifying changes of the shape of the high-temperature part of the LiF:Mg,Ti glow-curve after exposure to densely ionizing radiation. It was introduced in order to estimate the effective LET…

Instrumentation and Detectors · Physics 2014-02-28 P. Bilski , M. Sadel , J. Swakon , A. Weber

We present a model atmosphere analysis of optical VRI and infrared JHK photometric data of about two dozen ZZ Ceti stars. We first show from a theoretical point of view that the resulting energy distributions are not particularly sensitive…

Solar and Stellar Astrophysics · Physics 2009-07-22 P. Bergeron , S. K. Leggett , H. C. Harris

In order to accurately determine stellar properties, knowledge of the effective temperature of stars is vital. We implement Gaia and 2MASS photometry in the InfraRed Flux Method and apply it to over 360,000 stars across different…