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The mid- and far-infrared view on high-mass star formation, in particular with the results from the Herschel space observatory, has shed light on many aspects of massive star formation. However, these continuum studies lack kinematic…

Astrophysics of Galaxies · Physics 2014-05-21 J. Tackenberg , H. Beuther , Th. Henning , H. Linz , T. Sakai , S. E. Ragan , O. Krause , M. Nielbock , M. Hennemann , J. Pitann , A. Schmiedeke

To understand the chemistry of sulphur (S) in the interstellar medium, models need to be tested by observations of S-bearing molecules in different physical conditions. We analyse observations obtained with the IRAM 30m telescope towards 15…

Astrophysics of Galaxies · Physics 2023-10-17 F. Fontani , E. Roueff , L. Colzi , P. Caselli

We present a new radiative transfer method (SPH-M1RT) that is coupled dynamically with smoothed particle hydrodynamics (SPH). We implement it in the (task-based parallel) SWIFT galaxy simulation code but it can be straightforwardly…

Instrumentation and Methods for Astrophysics · Physics 2021-07-06 T. K. Chan , Tom Theuns , Richard Bower , Carlos Frenk

A radiative transfer method for the treatment of molecular lines is presented. We apply this method to previous SWAS and ISO observations of water vapor in the source S140 in order to make models to plan for, and to interpret, HIFI data.…

Astrophysics · Physics 2009-11-11 D. R. Poelman , M. Spaans

We present a review of the TORUS radiation transfer and hydrodynamics code. TORUS uses a 1-D, 2-D or3-D adaptive mesh refinement scheme to store and manipulate the state variables, and solves the equation of radiative transfer using Monte…

Solar and Stellar Astrophysics · Physics 2019-03-18 Tim Harries , Tom Haworth , David Acreman , Ahmad Ali , Tom Douglas

We describe a powerful methodology for numerical solution of 3-D self-gravitational hydrodynamics problems with extremely high resolution. Our method utilizes the technique of local adaptive mesh refinement (AMR), employing multiple grids…

Astrophysics · Physics 2016-01-27 Richard I. Klein , Robert T. Fisher , Christopher F. McKee , J. Kelly Truelove

We have invented a new algorithm to use with self-gravitating SPH Star Formation codes. The new method is designed to enable SPH simulations to self-regulate their numerical resolution, i.e. the number of SPH particles; the latter is…

Astrophysics · Physics 2007-05-23 Spyridon Kitsionas

Using the Torus radiative transfer code we produce synthetic observations of the 21 cm neutral hydrogen line from an SPH simulation of a spiral galaxy. The SPH representation of the galaxy is mapped onto an AMR grid, and a ray tracing…

Astrophysics of Galaxies · Physics 2015-05-18 David M. Acreman , Kevin A. Douglas , Clare L. Dobbs , Christopher M. Brunt

HII regions powered by ionizing radiation from massive stars drive the dynamical evolution of the interstellar medium. Fast radiative transfer methods for incorporating photoionization effects are thus essential in astrophysical…

Instrumentation and Methods for Astrophysics · Physics 2025-02-25 Cheryl S. C. Lau , Maya A. Petkova , Ian A. Bonnell

Spectral line and continuum observations of the ionized and molecular gas in G20.08-0.14 N explore the dynamics of accretion over a range of spatial scales in this massive star-forming region. Very Large Array observations of NH_3 at 4''…

Astrophysics of Galaxies · Physics 2015-05-14 Roberto Galván-Madrid , Eric Keto , Qizhou Zhang , Stan Kurtz , Luis F. Rodríguez , Paul T. P. Ho

We describe a grid-based numerical method for 3D hydrodynamic cosmological simulations which is adaptive in space and time and combines the best features of higher order--accurate Godunov schemes for Eulerian hydrodynamics with adaptive…

Astrophysics · Physics 2016-01-27 Michael L. Norman , Greg L. Bryan

The MHD version of the adaptive mesh refinement (AMR) code, MG, has been employed to study the interaction of thermal instability, magnetic fields and gravity through 3D simulations of the formation of collapsing cold clumps on the scale of…

Astrophysics of Galaxies · Physics 2020-11-11 C. J. Wareing , J. M. Pittard , S. A. E. G. Falle

What is the numerical reproducibility of a stellar system (including its discs) when evolving only a sub-set of (partially-evolved) smoothed particle hydrodynamics (SPH) particles? To investigate this, we modelled the evolution of 29 star…

Solar and Stellar Astrophysics · Physics 2024-01-10 James Wurster , Connar Rowan

We carry out adaptive mesh refinement (AMR) cosmological simulations of Milky-Way mass halos in order to investigate the formation of disk-like galaxies in a {\Lambda}-dominated Cold Dark Matter model. We evolve a suite of five halos to z =…

Astrophysics of Galaxies · Physics 2015-06-03 Cameron Hummels , Greg Bryan

Sufficiently massive clumps of molecular gas collapse under self-gravity and fragment to spawn a cluster of stars that have a range of masses. We investigate observationally the early stages of formation of a stellar cluster in a massive…

Solar and Stellar Astrophysics · Physics 2015-05-27 Qizhou Zhang , Ke Wang , Xing Lu , Izaskun Jimenez-Serra

Through synthetic observations of a hydrodynamical simulation of an evolving star-forming region, we assess how the choice of observational techniques affects the measurements of properties which trace star formation. Testing and…

Solar and Stellar Astrophysics · Physics 2017-11-01 Christine M. Koepferl , Thomas P. Robitaille , James E. Dale , Francesco Biscani

We describe the results of a sequence of simulations of gravitational collapse in a turbulent magnetized region. The parameters are chosen to be representative of molecular cloud material. We find that several protostellar cores and…

Astrophysics · Physics 2009-11-06 D. Balsara , D. Ward-Thompson , R. M. Crutcher

We present multi-wavelength global star formation rate (SFR) estimates for 326 galaxies from the Star Formation Reference Survey (SFRS) in order to determine the mutual scatter and range of validity of different indicators. The widely used…

Astrophysics of Galaxies · Physics 2018-11-07 Smriti Mahajan , M. L. N. Ashby , S. P. Willner , P. Barmby , G. G. Fazio , A. Maragkoudakis , S. Raychaudhury , A. Zezas

Comparison is made between a number of independent computer programs for radiative transfer in molecular rotational lines. The test models are spherically symmetric circumstellar envelopes with a given density and temperature profile. The…

We explore millimeter line diagnostics of an obscuring molecular torus modeled by a hydrodynamic simulation with three-dimensional nonLTE radiative transfer calculations. Based on the results of high-resolution hydrodynamic simulation of…

Astrophysics · Physics 2009-11-13 Masako Yamada , Keiichi Wada , Kohji Tomisaka