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We compare the three-dimensional gas temperature distributions obtained by a dedicated radiative transfer and photoionisation code, MOCASSIN, against those obtained by the recently-developed Smooth Particle Hydrodynamics (SPH) plus…

Astrophysics of Galaxies · Physics 2015-05-20 Barbara Ercolano , Matthias Gritschneder

Observations and magnetohydrodynamic simulations of solar and stellar atmospheres reveal an intermittent behavior or steep gradients in physical parameters, such as magnetic field, temperature, and bulk velocities. The numerical solution of…

Solar and Stellar Astrophysics · Physics 2019-03-22 Gioele Janett

A discrete spherical harmonics method is developed for the radiative transfer problem in inhomogeneous polarized planar atmosphere illuminated at the top by a collimated sunlight while the bottom reflects the radiation. The method expands…

Instrumentation and Methods for Astrophysics · Physics 2018-02-07 Romuald Tapimo , Hervé Thierry Tagne Kamdem , David Yemele

To advance our understanding of massive star formation, it is essential to perform a comprehensive suite of simulations that explore the relevant parameter space and include enough physics to enable a comparison with observational data. We…

Astrophysics of Galaxies · Physics 2025-11-19 Birka Zimmermann , Stefanie Walch , Seamus D. Clarke , Richard Wünsch , Andre Klepitko

Fitting spectral distributions of total fluxes or image intensities are two standard methods for estimating the masses of starless cores and protostellar envelopes. These mass estimates, which are the main source and basis of our knowledge…

Instrumentation and Methods for Astrophysics · Physics 2016-09-28 Alexander Men'shchikov

The fragmentation of star-forming interstellar clouds, and the resulting stellar initial mass function (IMF), is strongly affected by the temperature structure of the collapsing gas. Since radiation feedback from embedded stars can modify…

Astrophysics of Galaxies · Physics 2015-05-14 Mark R. Krumholz , Andrew J. Cunningham , Richard I. Klein , Christopher F. McKee

We present a new detailed model of the He I collisional-recombination spectrum based on the most up-to-date atomic data. The model accounts for radiative transfer effects and the influence of a non-zero optical depth in He I lines arising…

Astrophysics of Galaxies · Physics 2026-01-21 Oleg Kurichin , Alexandre Ivanchik

Spatially resolved studies of star forming regions show that the assumption of spherical geometry is not realistic in most cases, with a major complication posed by the gas being ionised by multiple non-centrally located stars or star…

Astrophysics · Physics 2009-06-23 B. Ercolano , N. Bastian , G. Stasinska

Context: Radiative feedback plays a crucial role in the formation of massive stars. The implementation of a fast and accurate description of the proceeding thermodynamics in pre-stellar cores and evolving accretion disks is therefore a main…

Solar and Stellar Astrophysics · Physics 2015-03-13 Rolf Kuiper , Hubert Klahr , Cornelis Dullemond , Wilhelm Kley , Thomas Henning

The [CII] 158$\mu$m emission line can arise in all phases of the ISM, therefore being able to disentangle the different contributions is an important yet unresolved problem when undertaking galaxy-wide, integrated [CII] observations. We…

Astrophysics of Galaxies · Physics 2016-11-23 Gioacchino Accurso , Amélie Saintonge , Thomas. G. Bisbas , Serena Viti

We study the inhomogeneous reionization in a critical density CDM universe due to stellar sources, including Population III objects. The spatial distribution of the sources is obtained from high resolution numerical N-body simulations. We…

Astrophysics · Physics 2009-10-31 B. Ciardi , A. Ferrara , F. Governato , A. Jenkins

Forming stars emit a substantial amount of radiation into their natal environment. We use ORION, an adaptive mesh refinement (AMR) three-dimensional gravito-radiation-hydrodynamics code, to simulate low-mass star formation in a turbulent…

Solar and Stellar Astrophysics · Physics 2009-09-28 S. S. R. Offner , R. I. Klein , C. F. McKee , M. R. Krumholz

We introduce and test a new and highly efficient method for treating the thermal and radiative effects influencing the energy equation in SPH simulations of star formation. The method uses the density, temperature and gravitational…

Astrophysics · Physics 2009-11-13 D. Stamatellos , A. P. Whitworth , T. Bisbas , S. Goodwin

We describe a technique for deriving effective temperatures, surface gravities, rotation velocities, and radial velocities from high resolution near-IR spectra. The technique matches the observed near-IR spectra to spectra synthesized from…

Astrophysics · Physics 2009-11-10 G. W. Doppmann , D. T. Jaffe

We present results from combining a grid-based radiative transfer code with a Smoothed Particle Hydrodynamics code to produce a flexible system for modelling radiation hydrodynamics. We use a benchmark model of a circumstellar disc to…

Solar and Stellar Astrophysics · Physics 2015-05-14 David M. Acreman , Tim J. Harries , David A. Rundle

Observations of the epoch of reionization give us clues about the nature and evolution of the sources of ionizing photons, or early stars and galaxies. We present a new suite of structure formation and radiative transfer simulations from…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-27 Keri L. Dixon , Ilian T. Iliev , Garrelt Mellema , Kyungjin Ahn , Paul R. Shapiro

We develop an analytic approach to study inhomogeneous reionization on large scales by solving the equations of ionization balance and radiative transfer to first order in perturbations. Given the spatial distribution and spectrum of the…

Astrophysics · Physics 2008-11-26 Jun Zhang , Lam Hui , Zoltan Haiman

Recent results from the James Webb Space Telescope show that nearby spiral galaxies are dominated by the presence of H I and H II bubbles that strongly shape their surrounding medium. These bubbles result from the feedback of high-mass…

High-fidelity spectroscopy presents challenges for both observations and in designing instruments. High-resolution and high-accuracy spectra are required for verifying hydrodynamic stellar atmospheres and for resolving intergalactic…

Instrumentation and Methods for Astrophysics · Physics 2015-05-18 Dainis Dravins

When modelling the ionisation of gas in the intergalactic medium after reionisation, it is standard practice to assume a uniform radiation background. This assumption is not always appropriate; models with radiative transfer show that…

Cosmology and Nongalactic Astrophysics · Physics 2020-09-02 Teresita Suarez , Andrew Pontzen