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The majority of hydrogen in the interstellar medium (ISM) is in atomic form. The transition from atoms to molecules and, in particular, the formation of the H$_2$ molecule, is a key step in cosmic structure formation en route to stars.…

Astrophysics of Galaxies · Physics 2018-10-31 Pei Zuo , Di Li , J. E. G. Peek , Qiang Chang , Xia Zhang , Nicholas chapman , Paul F. Goldsmith , Zhi-Yu Zhang

The spatial distribution of the gaseous components of the Milky Way is of great importance for a number of different fields, for example, Galactic structure, star formation, and cosmic rays. However, obtaining distance information to…

We have used archival FUSE data to complete a survey of interstellar HD in 41 lines of sight with a wide range of extinctions. This follow up to an earlier survey was made to further assess the utility of HD as a cosmological probe; to…

We use far-UV absorption spectra obtained with FUSE towards three late B stars to study the formation and excitation of H2 in the diffuse ISM. The data interpretation relies on a model of the chemical and thermal balance in…

We present ALMA observations of a small but statistically complete sample of twelve 250 micron selected galaxies at $z=0.35$ designed to measure their dust submillimeter continuum emission as well as their CO(1-0) and atomic carbon…

Astrophysics of Galaxies · Physics 2021-11-18 L. Dunne , S. J. Maddox , C. Vlahakis , H. L. Gomez

We report on the abundance of interstellar neutral oxygen (OI) for 26 sightlines, using data from the Far Ultraviolet Spectroscopic Explorer (FUSE), the International Spectroscopic Explorer (IUE), and the Hubble Space Telescope (HST). OI…

Astrophysics · Physics 2009-11-10 Adam G. Jensen , Brian L. Rachford , Theodore P. Snow

Our ability to trace the star-forming molecular gas is important to our understanding of the Universe. We can trace this gas using CO emission, converting the observed CO intensity into the H$_2$ gas mass of the region using the CO-to-H$_2$…

We have conducted OH 18 cm survey toward 141 molecular clouds in various environments, including 33 optical dark clouds, 98 Planck Galactic cold clumps (PGCCs) and 10 Spitzer dark clouds with the Arecibo telescope. The deviations from local…

Astrophysics of Galaxies · Physics 2020-12-23 Ningyu Tang , Di Li , Nannan Yue , Pei Zuo , Tie Liu , Gan Luo , Longfei Chen , Sheng-Li Qin , Yuefang Wu , Carl Heiles

Carbon monoxide is the most abundant molecule after H$_2$ and is important for chemistry in circumstellar envelopes around late-type stars. The size of the envelope is important when modelling low-J transition lines and deriving mass-loss…

Solar and Stellar Astrophysics · Physics 2017-10-18 M. A. T. Groenewegen

We investigate the correlation between extinction and H~{\sc i} and CO emission at intermediate and high Galactic latitudes ($|b|>10\degr$) within the footprint of the Xuyi Schmidt Telescope Photometric Survey of the Galactic anticentre…

Astrophysics of Galaxies · Physics 2015-06-23 B. -Q. Chen , X. -W. Liu , H. -B. Yuan , Y. Huang , M. -S. Xiang

Gas in protostellar disks provides the raw material for giant planet formation and controls the dynamics of the planetesimal-building dust grains. Accurate gas mass measurements help map the observed properties of planet-forming disks onto…

Earth and Planetary Astrophysics · Physics 2017-05-31 Mo Yu , Neal J. Evans , Sarah E. Dodson-Robinson , Karen Willacy , Neal J. Turner

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 present numerical computations and analysis of atomic to molecular (HI-to-H$_2$) transitions in cool ($\sim$100 K) low-metallicity dust-free (primordial) gas, in which molecule formation occurs via cosmic-ray driven negative ion…

Astrophysics of Galaxies · Physics 2021-10-27 Amiel Sternberg , Alon Gurman , Shmuel Bialy

Our understanding of how molecular clouds form in the interstellar medium (ISM) would be greatly helped if we had a reliable observational tracer of the gas flows responsible for forming the clouds. Fine structure emission from singly…

Astrophysics of Galaxies · Physics 2019-05-14 Paul C. Clark , Simon C. O. Glover , Sarah E. Ragan , Ana Duarte-Cabral

We present the study of CI/H$_2$ relative abundance in the diffuse cold neutral medium. Using the chemical and thermal balance model we calculated the dependence of CI/H$_2$ on the main parameters of the medium: hydrogen number density,…

Astrophysics of Galaxies · Physics 2024-02-02 Sergei Balashev , Daria Kosenko

CO is the most widely used observational tracer of molecular gas. The observable CO luminosity is translated to H_2 mass via a conversion factor, X_CO, which is a source of uncertainty and bias. Despite variations in X_CO, the…

Astrophysics of Galaxies · Physics 2020-11-18 Munan Gong , Eve C. Ostriker , Chang-Goo Kim , Jeong-Gyu Kim

We apply novel survival analysis techniques to investigate the relationship between a number of the properties of galaxies and their atomic ($M_\mathrm{HI}$) and molecular ($M_{\mathrm{H_2}}$) gas mass, with the aim of devising efficient,…

Astrophysics of Galaxies · Physics 2019-11-06 Hassen M. Yesuf , Luis C. Ho

We use the IRAM HERACLES survey to study CO emission from 33 nearby spiral galaxies down to very low intensities. Using atomic hydrogen (HI) data, mostly from THINGS, we predict the local mean CO velocity from the mean HI velocity. By…

This paper presents the first results of comparison of Planck along with IRAS data with Green Bank Telescope 21-cm observations in 14 fields covering more than 800 square degrees at high Galactic latitude. Galactic dust emission for fields…

Astrophysics of Galaxies · Physics 2015-05-27 Planck Collaboration , A. Abergel , P. A. R. Ade , N. Aghanim , M. Arnaud , M. Ashdown , J. Aumont , C. Baccigalupi , A. Balbi , A. J. Banday , R. B. Barreiro , J. G. Bartlett , E. Battaner , K. Benabed , A. Benoit , J. -P. Bernard , M. Bersanelli , R. Bhatia , K. Blagrave , J. J. Bock , A. Bonaldi , J. R. Bond , J. Borrill , F. R. Bouchet , F. Boulanger , M. Bucher , C. Burigana , P. Cabella , C. M. Cantalupo , J. -F. Cardoso , A. Catalano , L. Cayon , A. Challinor , A. Chamballu , L. -Y Chiang , C. Chiang , P. R. Christensen , D. L. Clements , S. Colombi , F. Couchot , A. Coulais , B. P. Crill , F. Cuttaia , L. Danese , R. D. Davies , R. J. Davis , P. de Bernardis , G. de Gasperis , A. de Rosa , G. de Zotti , J. Delabrouille , J. -M. Delouis , F. -X. Desert , C. Dickinson , S. Donzelli , O. Dore , U. Dorl , M. Douspis , X. Dupac , G. Efstathiou , T. A. Ensslin , H. K. Eriksen , F. Finelli , O. Forni , M. Frailis , E. Franceschi , S. Galeotta , K. Ganga , M. Giard , G. Giardino , Y. Giraud-Heraud , J. Gonzalez-Nuevo , K. M. Gorski , S. Gratton , A. Gregorio , A. Gruppuso , F. K. Hansen , D. Harrison , G. Helou , S. Henrot-Versille , D. Herranz , S. R. Hildebrandt , E. Hivon , M. Hobson , W. A. Holmes , W. Hovest , R. J. Hoyland , K. M. Huffenberger , A. H. Jaffe , G. Joncas , A. Jones , W. C. Jones , M. Juvela , E. Keihanen , R. Keskitalo , T. S. Kisner , R. Kneissl , L. Knox , H. Kurki-Suonio , G. Lagache , J. -M. Lamarre , A. Lasenby , R. J. Laureijs , C. R. Lawrence , S. Leach , R. Leonardi , C. Leroy , M. Linden-Vornle , F. J. Lockman , M. Lopez-Caniego , P. M. Lubin , J. F. Macias-Perez , C. J. MacTavish , B. Maffei , D. Maino , N. Mandolesi , R. Mann , M. Maris , D. J. Marshall , P. Martin , E. Martinez-Gonzalez , S. Masi , S. Matarrese , F. Matthai , P. Mazzotta , P. McGehee , P. R. Meinhold , A. Melchiorri , L. Mendes , A. Mennella , M. -A. Miville-Deschenes , A. Moneti , L. Montier , G. Morgante , D. Mortlock , D. Munshi , A. Murphy , P. Naselsky , F. Nati , P. Natoli , C. B. Netterfield , H. U. Norgaard-Nielsen , F. Noviello , D. Novikov , I. Novikov , I. J. O'Dwyer , S. Osborne , F. Pajot , R. Paladini , F. Pasian , G. Patanchon , O. Perdereau , L. Perotto , F. Perrotta , F. Piacentini , M. Piat , D. Pinheiro Goncalves , S. Plaszczynski , E. Pointecouteau , G. Polenta , N. Ponthieu , T. Poutanen , G. Prezeau , S. Prunet , J. -L. Puget , J. P. Rachen , W. T. Reach , M. Reinecke , C. Renault , S. Ricciardi , T. Riller , I. Ristorcelli , G. Rocha , C. Rosset , M. Rowan-Robinson , J. A. Rubino-Martin , B. Rusholme , M. Sandri , D. Santos , G. Savini , D. Scott , M. D. Seiffert , P. Shellard , G. F. Smoot , J. -L. Starck , F. Stivoli , V. Stolyarov , R. Stompor , R. Sudiwala , J. -F. Sygnet , J. A. Tauber , L. Terenzi , L. Toffolatti , M. Tomasi , J. -P. Torre , M. Tristram , J. Tuovinen , G. Umana , L. Valenziano , P. Vielva , F. Villa , N. Vittorio , L. A. Wade , B. D. Wandelt , A. Wilkinson , D. Yvon , A. Zacchei , A. Zonca

We present a method to simultaneously model the dust far-infrared spectral energy distribution (SED) and the total infrared $-$ carbon monoxide (CO) integrated intensity $(S_{\rm IR}-I_{\rm CO})$ relationship. The modelling employs a…

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