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We present the first results on the diffuse transition clouds observed in [CII] line emission at 158 microns (1.9 THz) towards Galactic longitudes near 340deg (5 LOSs) and 20deg (11 LOSs) as part of the GOT C+ survey. Out of the total 146…

Astrophysics of Galaxies · Physics 2015-05-19 T. Velusamy , W. D. Langer , J. L. Pineda , P. F. Goldsmith , D. Li. , H. W. Yorke

The 1-50 GHz GBT PRIMOS data contains ~50 molecular absorption lines observed in diffuse and translucent clouds located in the Galactic Center, Bar, and spiral arms in the line-of-sight to Sgr B2(N). We measure the column densities and…

Astrophysics of Galaxies · Physics 2018-02-14 Joanna Corby , Brett McGuire , Eric Herbst , Anthony Remijan

We present an all sky map of the diffuse Galactic far ultraviolet (1344-1786 Angstroms) background using GALEX data, covering 65% of the sky with 11.79 arcmin square pixels. We investigate the dependence of the background on Galactic…

Astrophysics of Galaxies · Physics 2015-06-17 Erika Hamden , David Schiminovich , Mark Seibert

The FUSE far-ultraviolet interstellar spectra toward seven targets in NGC 6231 show that the molecules H_2, HD, and CO as well as various atomic species are distributed in several clouds. The main absorption component found on the sight…

Astrophysics · Physics 2009-11-10 O. Marggraf , H. Bluhm , K. S. de Boer

We extend the non-equilibrium model for the chemical and thermal evolution of diffuse interstellar gas presented in Richings et al. (2014) to account for shielding from the UV radiation field. We attenuate the photochemical rates by dust…

Astrophysics of Galaxies · Physics 2015-06-19 Alexander J. Richings , Joop Schaye , Benjamin D. Oppenheimer

We present the far-ultraviolet (FUV) fluorescent molecular hydrogen (H_2) emission map of the Milky Way Galaxy obtained with FIMS/SPEAR covering ~76% of the sky. The extinction-corrected intensity of the fluorescent H_2 emission has a…

Astrophysics of Galaxies · Physics 2017-08-23 Young-Soo Jo , Kwang-Il Seon , Kyoung-Wook Min , Jerry Edelstein , Wonyong Han

The diffuse interstellar medium is dynamic, and its chemistry and evolution is determined by shock fronts as well as photodissociation. Shocks are implied by the supersonic motions and velocity dispersion often statistically called…

Astrophysics of Galaxies · Physics 2021-03-17 William T. Reach , Carl Heiles

We have developed a complete model of the hydrogen molecule as part of the spectral simulation code Cloudy. Our goal is to apply this to spectra of high-redshift star-forming regions where H2 absorption is seen, but where few other details…

Astrophysics · Physics 2009-11-13 Gargi Shaw , G. J. Ferland , R. Srianand , N. P. Abel

We use 3D-PDR, a three-dimensional astrochemistry code for modeling photodissociation regions (PDRs), to post-process hydrodynamic simulations of turbulent, star-forming clouds. We focus on the transition from atomic to molecular gas, with…

Solar and Stellar Astrophysics · Physics 2015-06-15 Stella S. R. Offner , Thomas G. Bisbas , Serena Viti , Thomas A. Bell

Gas and dust properties in the Chamaeleon molecular cloud complex have been investigated with emission lines from atomic hydrogen (HI) and 12CO molecule, dust optical depth at 353 GHz ($\tau_{353}$), and $J$-band infrared extinction…

Astrophysics of Galaxies · Physics 2019-06-26 Katsuhiro Hayashi , Ryuji Okamoto , Hiroaki Yamamoto , Takahiro Hayakawa , Kengo Tachihara , Yasuo Fukui

We have carried out high-resolution observations along one-dimensional cuts through the three Galactic supershells GS 064-01-97, GS 090-28-17, and GS 174+02-64 in the HI 21 cm and CO J=1-0 lines. By comparing the HI data with IRAS data, we…

Astrophysics · Physics 2007-05-23 Jeong-Eun Lee , Kee-Tae Kim , Bon-Chul Koo

We observed the 3335 MHz (9cm) F=1-1 line of CH toward a sample of diffuse clouds occulting compact extragalactic mm-wave continuum sources, using the old NRAO 43m telescope. Because radiofrequency observations of CH really must be…

Astrophysics · Physics 2009-11-07 H. Liszt , R. Lucas

Spectra obtained with the Hubble Space Telescope GHRS are combined with high-resolution optical spectra and UV spectra from Copernicus to study the abundances and physical conditions in the diffuse interstellar clouds seen along the line of…

Astrophysics · Physics 2008-11-26 D. E. Welty , L. M. Hobbs , J. T. Lauroesch , D. C. Morton , L. Spitzer , D. G. York

The chemical composition of diffuse interstellar clouds is not fully established. They host an active chemistry despite their relatively low density and the ubiquitous presence of far-UV radiation. To further explore the chemical…

Astrophysics of Galaxies · Physics 2025-11-21 Maryvonne Gerin , Harvey Liszt , Belen Tercero , Jose Cernicharo

To understand the conditions under which dense, molecular gas is able to form within a galaxy, we post-process a series of three-dimensional galactic-disk-scale simulations with ray-tracing based radiative transfer and chemical network…

We present a study of the three-dimensional structure of the molecular clouds in the Galactic Centre (GC) using CO emission and OH absorption lines. Two CO isotopologue lines, $^{12}$CO ($J$=1$\rightarrow$0) and $^{13}$CO…

We present a semi-analytical description of the relative HD/H2 abundance in the diffuse interstellar medium. We found three asymptotics of the relative HD/H$_2$ abundance for different parts of the medium and their dependence on the…

Astrophysics of Galaxies · Physics 2020-01-15 S. A. Balashev , D. N. Kosenko

We use a suite of hydrodynamics simulations of the interstellar medium (ISM) within a galactic disk, which include radiative transfer, a non-equilibrium model of molecular hydrogen, and a realistic model for star formation and feedback, to…

Astrophysics of Galaxies · Physics 2024-05-07 Ava Polzin , Andrey V. Kravtsov , Vadim A. Semenov , Nickolay Y. Gnedin

We present a theoretical investigation of CN and HCN molecule formation in dense interstellar clouds. We study the gas-phase CN and HCN production efficiencies from the outer photon-dominated regions (PDRs) into the opaque cosmic-ray…

Astrophysics · Physics 2009-11-13 Gai I. Boger , Amiel Sternberg

We study infrared emission of 17 isolated, diffuse clouds with masses of order solar masses, to test the hypothesis that grain property variations cause the apparently low gas-to-dust ratios that have been measured in those clouds. Maps of…

Astrophysics of Galaxies · Physics 2018-08-13 William T. Reach , Jean-Philippe Bernard , Thomas Jarrett , Carl Heiles
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