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Several galaxies, such as dwarfs and Irregulars as well as outer galactic clouds have low metallicity. At low metallicities a reduction in the amount of dust and heavy elements plays a significant role on the chemistry as well as the…

Astrophysics · Physics 2007-05-23 S. Jeyakumar , J. Stutzki

This study explores the link between the [OIII]88mu emission, a well-known tracer of HII regions, and 24mu continuum, often used to trace warm dust in the ionized phases of galaxies. We investigate the local conditions driving the relation…

More complete knowledge of galaxy evolution requires understanding the process of star formation and interaction between the interstellar radiation field and the interstellar medium in galactic environments traversing a wide range of…

We present observations of HDCO and H2CO emission toward a sample of 15 Class 0 protostars in the Orion A and B clouds. Of these, eleven protostars are Herschel-identified PACS Bright Red Sources (PBRS) and four are previously identified…

Astrophysics of Galaxies · Physics 2015-10-14 Miju Kang , Minho Choi , Amelia M. Stutz , Ken'ichi Tatematsu

The article deals with observations of star-forming regions S231-S235 in 'quasi-thermal' lines of ammonia (NH$_3$), cyanoacetylene (HC$_3$N) and maser lines of methanol (CH$_3$OH) and water vapor (H$_2$O). S231-S235 regions is situated in…

Astrophysics of Galaxies · Physics 2016-05-31 D. A. Ladeyschikov , M. S. Kirsanova , A. P. Tsivilev , A. M. Sobolev

Young massive stars regulate the physical conditions, ionization, and fate of their natal molecular cloud. It is important to find tracers that help quantifying the stellar feedback processes that take place at different scales. We present…

We present 5--14~$\mu$m spectra at two different positions across the Orion Bar photodissociation region (PDR) obtained with the Infrared Spectrograph onboard the Spitzer Space Telescope and 3.3~$\mu$m PAH observations obtained with the…

Astrophysics of Galaxies · Physics 2021-11-03 C. Knight , E. Peeters , A. G. G. M. Tielens , W. D. Vacca

C$_2$H is a representative hydrocarbon that is abundant and ubiquitous in the interstellar medium (ISM). To study its chemical properties, we present Submillimeter Array (SMA) observations of the C$_2$H $N=3-2$ and HC$_3$N $J=30-29$…

Solar and Stellar Astrophysics · Physics 2015-08-06 Xue-Jian Jiang , Hauyu Baobab Liu , Qizhou Zhang , Junzhi Wang , Zhi-Yu Zhang , Juan Li , Yu Gao , Qiusheng Gu

We present results of analysis of physical conditions (number density, intensity of UV field, kinetic temperature) in the cold H$_2$-bearing interstellar medium of local and high redshift galaxies. Our measurements based on the fit to the…

Astrophysics of Galaxies · Physics 2020-10-07 V. V. Klimenko , S. A. Balashev

We present a model for the hydrogenation states of Polycyclic Aromatic Hydrocarbons (PAHs) in the diffuse interstellar medium. First, we study the abundance of hydrogenation and charge states of PAHs due to photo-ionization,…

Astrophysics · Physics 2007-05-23 My Ha Vuong , Bernard H. Foing

We investigate the formation of molecular hydrogen (H_2) in a primordial H+He gas cloud irradiated by a power-law UV flux. We find that at high densities (>1 cm^{-3}) and low temperatures (<10^4 K), the background radiation enhances the…

Astrophysics · Physics 2009-10-28 Zoltan Haiman , Martin Rees , Abraham Loeb

We have studied the influence of far ultraviolet (UV) radiation from a massive young stellar object (YSO) on the chemistry of its own envelope by extending the models of Doty et al. (2002) to include a central source of UV radiation. The…

Astrophysics · Physics 2009-11-10 P. Stauber , S. D. Doty , E. F. van Dishoeck , J. K. Jorgensen , A. O. Benz

We present wide-field, deep narrowband H$_2$, Br$\gamma$, H$\alpha$, [S II], [O III], and broadband I and K-band images of the Carina star formation region. The new images provide a large-scale overview of all the H$_2$ and Br$\gamma$…

Solar and Stellar Astrophysics · Physics 2015-06-23 P. Hartigan , M. Reiter , N. Smith , J. Bally

The observed molecular properties of a sample of FIR-luminous and OH megamaser (OH-MM) galaxies have been investigated. The ratio of high and low-density tracer lines is found to be determined by the progression of the star formation in the…

Astrophysics · Physics 2009-11-13 A. F. Loenen , W. A. Baan , M. Spaans

Modern observations of the interstellar medium (ISM) in galaxies detect a variety of atomic and molecular species. The goal is to connect these observations to the astrochemical properties of the ISM. 3D hydro-chemical simulations attempt…

Astrophysics of Galaxies · Physics 2019-02-20 Thomas G. Bisbas , Andreas Schruba , Ewine F. van Dishoeck

Using data from the Green Bank Telescope, we analyze the radio continuum (free-free) and radio recombination line (RRL) emission of the compact HII region NGC 7538 (Sharpless 158). We detect extended radio continuum and hydrogen RRL…

Astrophysics of Galaxies · Physics 2016-06-29 Matteo Luisi , L. D. Anderson , Dana S. Balser , T. M. Bania , Trey V. Wenger

We have discovered 12 new molecular hydrogen emission-line objects (MHOs) in the vicinity of the candidate massive young stellar object Mol 121, in addition to five that were previously known. H2 2.12-micron/H2 2.25-micron flux ratios…

Astrophysics of Galaxies · Physics 2015-06-12 G. Wolf-Chase , K. Arvidsson , M. Smutko , R. Sherman

Estimating molecular abundances ratios from the direct measurement of the emission of the molecules towards a variety of interstellar environments is indeed very useful to advance in our understanding of the chemical evolution of the…

Astrophysics of Galaxies · Physics 2018-09-12 S. Paron , M. B. Areal , M. E. Ortega

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

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