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We present new calculations of Rosseland and Planck gaseous mean opacities relevant to the atmospheres of giant planets and ultracool dwarfs. Such calculations are used in modeling the atmospheres, interiors, formation, and evolution of…

Earth and Planetary Astrophysics · Physics 2021-06-28 Richard S. Freedman , Jacob Lustig-Yaeger , Jonathan J. Fortney , Roxana E. Lupu , Mark S. Marley , Katharina Lodders

A determination is made of the radiation emitted by a linearly uniformly accelerated uncharged dipole transmitter. It is found that, first of all, the radiation rate is given by the familiar Larmor formula, but it is augmented by an amount…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Ulrich H. Gerlach

The Petersen diagram is a frequently used tool to constrain model parameters such as metallicity of radial double-mode pulsators. In this diagram the period ratio of the radial first overtone to the fundamental mode, P_1/P_0, is plotted…

Astrophysics · Physics 2008-11-26 P. Lenz , A. A. Pamyatnykh , M. Breger

Elemental abundances of carbon, nitrogen, oxygen, magnesium, aluminum, and silicon are presented for a sample of twelve rapidly rotating OB star (v sin i > 60 km s^-1) members of the Cep OB2, Cyg OB3 and Cyg OB7 associations. The abundances…

Astrophysics · Physics 2009-11-07 Simone Daflon , Katia Cunha , Keith Butler , Verne V. Smith

Cepheid masses derived from pulsations or binary dynamics are generally lower than those derived from stellar evolution models. Recent efforts have been dedicated to investigating the effects of abundances, mass loss, rotation, convection…

Solar and Stellar Astrophysics · Physics 2020-04-14 Joyce A. Guzik , Ebraheem Farag , Jakub Ostrowski , Nancy R. Evans , Hilding Neilson , Sofia Moschou , Jeremy J. Drake

Previous computations of low temperature Rosseland and Planck mean opacities from Alexander & Ferguson (1994) are updated and expanded. The new computations include a more complete equation of state with more grain species and updated…

The present debate on the reliability of astrophysical opacities has reached a new climax with the recent measurements of Fe opacities on the Z-machine at the Sandia National Laboratory \citep{Bailey2015}. To understand the differences…

Solar and Stellar Astrophysics · Physics 2018-04-11 F. Delahaye , N. R. Badnell , C. P. Ballance , P. Palmeri , S. Preval , P. Quinet , C. Ramsbottom , R. T. Smyth , M. Turkington , C. J. Zeippen

We report on oxygen abundances determined from medium-resolution near-IR spectroscopy for a sample of 57 carbon-enhanced metal-poor (CEMP) stars selected from the Hamburg/ESO survey. The majority of our program stars exhibit oxygen-to-iron…

We compare eighteen binary systems with precisely determined radii and masses from 23 to 1.1 M_sol, and stellar evolution models produced with our newly revised code TYCHO. ``Overshooting'' and rotational mixing were suppressed in order to…

Astrophysics · Physics 2009-11-06 P. A. Young , E. E. Mamajek , David Arnett , James Liebert

Los Alamos National Laboratory has calculated a new generation of radiative opacities (OPLIB data using the ATOMIC code) for elements with atomic number Z=1-30 with improved physics input, updated atomic data, and finer temperature grid to…

Solar and Stellar Astrophysics · Physics 2016-05-17 Joyce A. Guzik , C. J. Fontes , P. Walczak , S. R. Wood , K. Mussack , E. Farag

Accurate determination of opacity is critical for understanding radiation transport in both astrophysical and laboratory plasmas. We employ atomic data from R-Matrix calculations to investigate radiative properties in high-energy-density…

High Energy Astrophysical Phenomena · Physics 2025-10-24 Anil K. Pradhan , Sultana N. Nahar

To support of our experimental studies on dielectric laser acceleration, numerical studies of laser acceleration of nonrelativistic electrons with the initial energy of 33.9 keV in transparent and reflective periodic structures are car-ried…

Accelerator Physics · Physics 2024-11-26 I. V. Beznosenko , A. V. Vasyliev , G. V. Sotnikov , G. O. Krivonosov

A detailed comparison is carried out between two popular equations of state (EOS), the Mihalas-Hummer-Dappen (MHD) and the OPAL equations of state, which have found widespread use in solar and stellar modeling during the past two decades.…

Astrophysics · Physics 2009-11-11 R. Trampedach , W. Dappen , V. A. Baturin

Due to the high quality constraints available for the Sun, we can carry out combined analyses using neutrino, spectroscopic and helioseismic observations. Such studies lay the ground for future improvements of key physical components of…

For the reliable analysis and modelling of astrophysical, laser-produced and fusion plasmas, atomic data are required for a number of parameters, including energy levels, radiative rates and electron impact excitation rates. Such data are…

Instrumentation and Methods for Astrophysics · Physics 2013-01-15 Km Aggarwal , Fp Keenan

Latest developments in theoretical computations since the international Opacity Project (OP), under the new the Iron Project (IP) and extensions, are described for applications to a variety of objects such as stellar atmospheres, nebulae,…

Astrophysics · Physics 2016-08-30 Sultana N. Nahar

Despite the fact that the first-order beam dynamics models allow an approximated evaluation of the beam properties, their contribution is essential during the conceptual design of an accelerator or beamline. However, during the…

Accelerator Physics · Physics 2017-12-20 V. Rizzoglio , A. Adelmann , C. Baumgarten , M. Frey , A. Gerbershagen , D. Meer , J. M. Schippers

Accurate atomic data are essential for opacity calculations and for abundance analyses of the Sun and other stars. The aim of this work is to provide accurate and extensive results of energy levels and transition data for C I - IV. The…

Atomic Physics · Physics 2021-02-03 W. Li , A. M. Amarsi , A. Papoulia , J. Ekman , P. Jönsson

The identification of non-radial g-mode oscillations as the cause of variability in cool subdwarf B stars (PG1716 variables) has been frustrated by a 5 000 K discrepancy between the observed and theoretical blue edge of the instability…

Astrophysics · Physics 2009-11-11 C. S. Jeffery , H. Saio

We present new Rosseland and Planck mean opacity tables relevant to the shallow interiors and atmospheres of giant planets. The tables span metallicities from 0.31 to 50 times solar, temperatures from 100 - 6000 K, and pressures from 1e-6 -…

Earth and Planetary Astrophysics · Physics 2026-01-07 Louis Siebenaler , Yamila Miguel