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We numerically examine the exterior solution of spherically symmetric and static configuration in scalar-tensor theories by using the nonminimally coupled scalar field with zero potential as our sample model. Our main purpose in this work…

General Relativity and Quantum Cosmology · Physics 2023-03-20 A. Savaş Arapoğlu , Sermet Çağan , A. Emrah Yükselci

We introduce a new 1D stellar spectral synthesis Python code called stardis. stardis is a modular, open-source radiative transfer code that is capable of spectral synthesis from near-UV to IR for FGK stars. We describe the structure,…

The spherical-harmonics expansion is a mathematically rigorous procedure and a powerful tool for the representation of potential energy surfaces of interacting molecular systems, determining their spectroscopic and dynamical properties,…

We present a numerical code to simulate maps of Galactic emission in intensity and polarization at microwave frequencies, aiding in the design of Cosmic Microwave Background experiments. This Python code builds on existing efforts to…

Cosmology and Nongalactic Astrophysics · Physics 2017-06-21 Ben Thorne , Jo Dunkley , David Alonso , Sigurd Naess

In light of its ubiquitous presence in the interstellar gas, the chemistry and reactivity of the HCO+ ion requires special attention. The availability of up-to-date collisional data between this ion and the most abundant perturbing species…

Astrophysics of Galaxies · Physics 2022-01-13 F. Tonolo , L. Bizzocchi , M. Melosso , F. Lique , L. Dore , V. Barone , C. Puzzarini

One of the biggest problems we can encounter while dealing with the limb-darkening coefficients for stellar atmospheric models with spherical symmetry is the difficulty of adjusting both the limb and the central parts simultaneously. In…

Solar and Stellar Astrophysics · Physics 2018-10-10 Antonio Claret

Context: The solution of the nonlocal thermodynamical equilibrium (non-LTE) radiative transfer equation usually relies on stationary iterative methods, which may falsely converge in some cases. Furthermore, these methods are often unable to…

Solar and Stellar Astrophysics · Physics 2015-07-29 Julien Lambert , Eric Josselin , Nils Ryde , Alexandre Faure

One of the current opportunities for stellar atmospheric modeling is the interpretation of optical interferometric data of stars. Starting from the robust, open source ATLAS atmospheric code (Kurucz, 1979), we have developed a spherically…

Astrophysics · Physics 2009-11-13 Hilding R. Neilson , John B. Lester

We have developed a numerical model for the temporal evolution of particle and photon spectra resulting from nonthermal processes at the shock fronts formed in merging clusters of galaxies. Fermi acceleration is approximated by injecting…

Astrophysics · Physics 2007-05-23 R. C. Berrington , C. D. Dermer

High-resolution images of the solar surface show a granulation pattern of hot rising and cooler downward-sinking material -- the top of the deep-reaching solar convection zone. Convection plays a role for the thermal structure of the solar…

Solar and Stellar Astrophysics · Physics 2011-12-14 Bernd Freytag , Matthias Steffen , Hans-Günter Ludwig , Sven Wedemeyer-Böhm , Werner Schaffenberger , Oskar Steiner

We develop an efficient numerical scheme for the 3D mean-field spherical dynamo equation. The scheme is based on a semi-implicit discretization in time and a spectral method in space based on the divergence-free spherical harmonic…

Numerical Analysis · Mathematics 2019-10-04 Ting cheng , Lina Ma , Jie Shen

Although the formalism of Lecavelier des Etangs et al. (2008) is extremely useful to understand what shapes transmission spectra of exoplanets, it does not include the effects of a sharp change in flux with altitude generally associated…

Earth and Planetary Astrophysics · Physics 2017-03-22 Yan Bétrémieux , Mark R. Swain

Sphere decoding (SD) of polar codes is an efficient method to achieve the error performance of maximum likelihood (ML) decoding. But the complexity of the conventional sphere decoder is still high, where the candidates in a target sphere…

Information Theory · Computer Science 2013-08-14 Kai Niu , Kai Chen , Jiaru Lin

We present the analysis of emission lines in high-resolution optical spectra of the planet-host star Proxima Centauri (Proxima) classified as a M5.5V\@. We carry out the detailed analysis of observed spectra to get a better understanding of…

Solar and Stellar Astrophysics · Physics 2017-10-11 Ya. V. Pavlenko , A. Suarez Mascareno , R. Rebolo , N. Lodieu , V. J. S. Bejar , J. I. Gonzalez Hernandez

Massive stars play an important role in the mechanical and chemical evolution of galaxies. Understanding the internal processes of these stars is vital to our understanding of their evolution and eventual end products. Deformations from…

Solar and Stellar Astrophysics · Physics 2020-04-29 Michael Abdul-Masih , Hugues Sana , Kyle E. Conroy , Jon Sundqvist , Andrej Prša , Angela Kochoska , Joachim Puls

We develop a method of analyzing radio frequency spectral line observations to derive data on the temperature, density, velocity, and molecular abundance of the emitting gas. The method incorporates a radiative transfer code with a new…

Astrophysics · Physics 2009-11-10 Eric Keto , George B. Rybicki , Edwin A. Bergin , Rene Plume

In this paper we report on the improvements implemented in the cosmological radiative transfer code CRASH. In particular we present a new multi-frequency algorithm for spectra sampling which makes use of colored photon packets: we discuss…

Astrophysics · Physics 2009-11-13 A. Maselli , B. Ciardi , A. Kanekar , .

Taking advantage of the unprecedented statistical power of upcoming cosmic shear surveys will require exquisite knowledge of the matter power spectrum over a wide range of scales. Analytical methods can achieve such precision only up to…

Cosmology and Nongalactic Astrophysics · Physics 2022-03-23 Matteo Cataneo

We present a new particle code for modelling the evolution of galaxies. The code is based on a multi-phase description for the interstellar medium (ISM). We included star formation (SF), stellar feedback by massive stars and planetary…

Astrophysics · Physics 2009-11-11 Stefan Harfst , Christian Theis , Gerhard Hensler

A new model is presented for spin-exchange optical pumping using an open-source code, ElmerFEM-CSC. The model builds on previous models by adding the effects of alkali-vapor heterogeneity in optical pumping cells and by modeling the effects…

Other Condensed Matter · Physics 2020-09-14 Geoffry M. Schrank