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The $\rm H_2$ mass of molecular clouds has traditionally been traced by the CO(J=1-0) rotational transition line. This said, CO is relatively easily photodissociated, and can also be destroyed by cosmic rays, thus rendering some fraction of…

Astrophysics of Galaxies · Physics 2018-12-26 Qi Li , Desika Narayanan , Romeel Dave , Mark R. Krumholz

We present new high resolution and dynamic range dust column density and temperature maps of the California Molecular Cloud derived from a combination of Planck and Herschel dust-emission maps, and 2MASS NIR dust-extinction maps. We used…

Astrophysics of Galaxies · Physics 2017-10-25 Charles J. Lada , John A. Lewis , Marco Lombardi , João Alves

We aim to better understand the emission of molecular tracers of the diffuse and dense gas in giant molecular clouds and the influence that metallicity, optical extinction, density, far-UV field, and star formation rate have on these…

We report the spatial distribution and physical characteristics of molecular clouds in the G24 region, which is located near the intersection of the Milky Way's Galactic bar with the Norma arm and the 3 kpc arm. Utilizing molecular line…

Astrophysics of Galaxies · Physics 2025-03-21 Tian Yang , Xi Chen , Xiao-Yun Xu , Yang Yang , En Chen , Jun Li , Bing-Gang Ju , Deng-Rong Lu

We present three-dimensional astrochemical simulations and synthetic observations of magnetised, turbulent, self-gravitating molecular clouds. We explore various galactic interstellar medium environments, including cosmic-ray ionization…

Astrophysics of Galaxies · Physics 2021-01-20 Thomas G. Bisbas , Jonathan C. Tan , Kei E. I. Tanaka

We report high resolution observations of the $^{12}$CO$(1\rightarrow0)$ and $^{13}$CO$(1\rightarrow0)$ molecular lines in the Carina Nebula and the Gum 31 region obtained with the 22-m Mopra telescope as part of the The Mopra Southern…

We study the relationship between molecular gas and dust in the California Molecular Cloud over an unprecedented dynamic range of cloud depth (Av = 3 - 60 magnitudes). We compare deep Herschel-based measurements of dust extinction with…

Astrophysics of Galaxies · Physics 2021-02-24 John Arban Lewis , Charles Lada , John Bieging , Anoush Kazarians , João Alves , Marco Lombardi

We present a quantitatively accurate machine-learning (ML) model for the computational prediction of core-electron binding energies, from which x-ray photoelectron spectroscopy (XPS) spectra can be readily obtained. Our model combines…

We report a new analysis protocol for HCN hyperfine data, based on the PYSPECKIT package, and results of using this new protocol to analyse a sample area of seven massive molecular clumps from the Census of High- and Medium-mass Protostars…

Astrophysics of Galaxies · Physics 2017-01-25 W. J. Schap , P. J. Barnes , A. Ordonez , A. Ginsburg , Y. Yonekura , Y. Fukui

We present the first study of the relationship between the column density distribution of molecular clouds within nearby Galactic spiral arms and their evolutionary status as measured from their stellar content. We analyze a sample of 195…

Astrophysics of Galaxies · Physics 2015-09-09 J. Abreu-Vicente , J. Kainulainen , A. Stutz , T. Henning , H. Beuther

[Abridged] Molecular filaments have received special attention recently, thanks to new observational results on their properties. In particular, our early analysis of filament properties revealed a narrow distribution of median widths…

We analyse synthetic $^{12}$CO, $^{13}$CO, and [CII] emission maps of simulated molecular clouds of the SILCC-Zoom project, which include an on-the-fly evolution of H$_2$, CO, and C$^+$. We use simulations of hydrodynamical and…

Astrophysics of Galaxies · Physics 2022-07-12 S. Ebagezio , D. Seifried , S. Walch , P. C. Nürnberger , T. E. Rathjen , T. Naab

We aim to develop the Orion B Giant Molecular Cloud (GMC) as a local template for interpreting extra-galactic molecular line observations. We use the wide-band receiver at the IRAM-30m to spatially and spectrally resolve the Orion B GMC.…

We revisit the mass-size relation of molecular cloud structures based on the column density map of the Cygnus-X molecular cloud complex. We extract 135 column density peaks in Cygnus-X and analyze the column density distributions around…

Astrophysics of Galaxies · Physics 2022-05-18 Yuchen Xing , Keping Qiu

We have developed a code that models the formation, destruction, radiative transfer, and vibrational/rotational excitation of H_2 in a detailed fashion. We discuss how such codes, together with FUSE observations of H_2 in diffuse and…

Astrophysics · Physics 2009-11-07 Matthew K. Browning , Jason Tumlinson , J. Michael Shull

Observations of molecular clouds in metal-poor environments typically find that they have much higher star formation rates than one would expect based on their observed CO luminosities and the molecular gas masses that are inferred from…

Astrophysics of Galaxies · Physics 2015-06-04 Simon C. O. Glover , Paul C. Clark

While the CO(1-0) transition is often used to deduce the total molecular hydrogen in galaxies, it is challenging to detect in low metallicity galaxies, in spite of the star formation taking place. In contrast, the [CII] 158 micron line is…

Aims: Our aims are threefold: a) To compare the $uv$ and mm-wave results; b) to interpret 13CO and 12CO abundances in terms of the physical processes which separately and jointly determine them; c) to interpret observed J=1-0 rotational…

Astrophysics · Physics 2009-11-13 H. S. Liszt

Determining the efficiency with which gas is converted into stars in galaxies requires an accurate determination of the total reservoir of molecular gas mass. However, despite being the most abundant molecule in the Universe, H$_2$ is…

The chemical structure of neutral clouds in low metallicity environments is examined with particular emphasis on the H to H_2 and C+ to CO transitions. We observed near-IR H_2 lines and the CO J=1-0 line from 30 Doradus and N159/N160 in the…

Astrophysics · Physics 2014-10-13 Soojong Pak , D. T. Jaffe , Ewine F. van Dishoeck , L. E. B. Johansson , R. S. Booth