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We characterize the column density probability distributions functions (PDFs) of the atomic hydrogen gas, HI, associated with seven Galactic molecular clouds (MCs). We use 21 cm observations from the Leiden/Argentine/Bonn Galactic HI Survey…

Astrophysics of Galaxies · Physics 2016-10-05 Nia Imara , Blakesley Burkhart

We present PPMAP, a Bayesian procedure that uses images of dust continuum emission at multiple wavelengths to produce resolution-enhanced image cubes of differential column-density as a function of dust temperature and position. PPMAP is…

Instrumentation and Methods for Astrophysics · Physics 2015-11-04 K. A. Marsh , A. P. Whitworth , O. Lomax

We analyse column density and temperature maps derived from Herschel dust continuum observations of a sample of massive infrared dark clouds (G11.11-0.12, G18.82-0.28, G28.37+0.07, G28.53-0.25). We disentangle the velocity structure of the…

Astrophysics of Galaxies · Physics 2015-05-27 N. Schneider , T. Csengeri , R. S. Klessen , P. Tremblin , V. Ossenkopf , N. Peretto , R. Simon , S. Bontemps , C. Federrath

Diffuse gamma-ray emission from interstellar clouds results largely from cosmic ray (CR) proton collisions with ambient gas, regardless of the gas state, temperature, or dust properties of the cloud. The interstellar medium is predominantly…

High Energy Astrophysical Phenomena · Physics 2017-01-11 Ryan D. Abrahams , Alex Teachey , Timothy A. D. Paglione

Eclipsing binaries provide one of the most direct mechanisms for measuring stellar properties such as mass and radius, but historically, determining these properties has been non-trivial and computationally prohibitive. As such, only a…

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

Star formation is intimately linked to the dynamical evolution of molecular clouds. Turbulent fragmentation determines where and when protostellar cores form, and how they contract and grow in mass via accretion from the surrounding cloud…

Astrophysics · Physics 2007-05-23 Ralf Klessen

We present new analytic theory and radiative transfer computations for the atomic to molecular (HI-to-H2) transitions, and the build-up of atomic-hydrogen (HI) gas columns, in optically thick interstellar clouds, irradiated by…

Astrophysics of Galaxies · Physics 2015-06-19 Amiel Sternberg , Franck Le Petit , Evelyne Roueff , Jacques Le Bourlot

We report the results of a 100 square degree survey of the Taurus Molecular Cloud region in the J = 1-0 transition of 12CO and 13CO. The image of the cloud in each velocity channel includes ~ 3 million Nyquist sampled pixels on a 20" grid.…

Astrophysics · Physics 2009-12-08 Paul F. Goldsmith , Mark Heyer , Gopal Narayanan , Ronald Snell , Di Li , Chris Brunt

We present analytic theory for the total column density of singly ionized carbon (C+) in the optically thick photon dominated regions (PDRs) of far-UV irradiated (star-forming) molecular clouds. We derive a simple formula for the C+ column…

Astrophysics of Galaxies · Physics 2016-08-31 Raanan Nordon , Amiel Sternberg

Sub-millimetre dust emission is often used to derive the column density N of dense interstellar clouds. The observations consist of data at several wavelengths but of variable resolution. We examine two procedures that been proposed for the…

Astrophysics of Galaxies · Physics 2015-06-15 M. Juvela , J. Malinen , T. Lunttila

We construct models of molecular clouds that are considered as ensembles of transient cores. Each core is assumed to develop in the background gas of the cloud, grow to high density and decay into the background. The chemistry in each core…

Astrophysics · Physics 2009-11-13 R. T. Garrod , D. A. Williams , J. M. C. Rawlings

We review recent advances in the analytical and numerical modeling of the star formation rate in molecular clouds and discuss the available observational constraints. We focus on molecular clouds as the fundamental star formation sites,…

Turbulent mixing layers (TMLs) are ubiquitous in multiphase gas. They can potentially explain observations of high ions such as O VI, which have significant observed column densities despite short cooling times. Previously, we showed that…

Astrophysics of Galaxies · Physics 2021-09-01 Brent Tan , S. Peng Oh

Aims. We aim to improve a previous model for the prediction of column densities and deuterium fractions of non- and singly deuterated methanol. Thereby, we try to identify crucial chemical and physical parameters, for which the study of…

Astrophysics of Galaxies · Physics 2023-12-20 W. Riedel , O. Sipilä , E. Redaelli , P. Caselli , A. I. Vasyunin , F. Dulieu , N. Watanabe

Most gas in giant molecular clouds is relatively low-density and forms star inefficiently, converting only a small fraction of its mass to stars per dynamical time. However, star formation models generally predict the existence of a…

Solar and Stellar Astrophysics · Physics 2019-08-28 Shivan Khullar , Mark R. Krumholz , Christoph Federrath , Andrew J. Cunningham

Clouds containing molecular dark matter in quantities relevant for star formation may exist in minihaloes of the type of cold dark matter included in many cosmological simulations or in the regions of some galaxies extending far beyond…

Astrophysics · Physics 2008-11-26 T. A. Bell , T. W. Hartquist , S. Viti , D. A. Williams

We present an analysis of probability distribution functions (pdfs) of column density in different zones of the star-forming region Perseus and its diffuse environment based on the map of dust opacity at 353 GHz available from the Planck…

Astrophysics of Galaxies · Physics 2015-08-06 Orlin Stanchev , Todor V. Veltchev , Jens Kauffmann , Sava Donkov , Rahul Shetty , Bastian Körtgen , Ralf S. Klessen

We introduce a model for the large-scale, global 3D structure of molecular clouds. Motivated by the morphological appearance of clouds in surface density maps, we model clouds as cylinders, with the aim of backing out information about the…

Astrophysics of Galaxies · Physics 2023-09-12 Nia Imara , John C. Forbes

The high ionization-state ions trace the hot gases in the universe, of which gaseous halos around galaxies are a major contributor. Following Qu & Bregman (2018), we calculate the gaseous halo contribution to the observed column density…

Astrophysics of Galaxies · Physics 2018-08-01 Zhijie Qu , Joel N. Bregman
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