Molecular absorption lines toward star-forming regions: a comparative study of HCO+, HNC, HCN, and CN

  title={Molecular absorption lines toward star-forming regions: a comparative study of HCO+, HNC, HCN, and CN},
  author={Benjamin Godard and E. Falgarone and Maryvonne Gerin and Pierre Hily-Blant and Massimo De Luca},
  journal={Astronomy and Astrophysics},
Aims. The comparative study of several molecular species at the origin of the gas phase chemistry in the diffuse interstellar medium (ISM) is a key input in unraveling the coupled chemical and dynamical evolution of the ISM. Methods. The lowest rotational lines of HCO + , HCN, HNC, and CN were observed at the IRAM-30m telescope in absorption against the λ 3m m andλ1.3 mm continuum emission of massive star-forming regions in the Galactic plane. The absorption lines probe the gas over kiloparsecs… 
The Role of Neutral Hydrogen in Setting the Abundances of Molecular Species in the Milky Way’s Diffuse Interstellar Medium. I. Observational Constraints from ALMA and NOEMA
We have complemented existing observations of H i absorption with new observations of HCO+, C2H, HCN, and HNC absorption from the Atacama Large Millimeter/submillimeter Array and the Northern
[C II] absorption and emission in the diffuse interstellar medium across the Galactic plane
Aims. Ionized carbon is the main gas-phase reservoir of carbon in the neutral diffuse interstellar medium (ISM) and its 158 μm fine structure transition [C ii] is the most important cooling line of
Molecular gas in absorption and emission along the line of sight to W31C G10.62-0.38
We used the ARO 12m antenna to observe emission from the J=1-0 lines of carbon monoxide, \hcop\ and HNC and the J=2-1 line of CS toward and around the continuum peak used for absorption studies and
Molecular ion abundances in the diffuse ISM: CF+, HCO+, HOC+, and C3H+
Aims. The transition between atomic and molecular hydrogen is associated with important changes in the structure of interstellar clouds, and marks the beginning of interstellar chemistry. Most
Dense gas in M 33 (HerM33es)
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
Detection of a dense clump in a filament interacting with W51e2
In the framework of the Herschel/PRISMAS guaranteed time key program, the line of sight to the distant ultracompact H ii region W51e2 has been observed using several selected molecular species. Most
Absorption lines from the molecules OH+, H2O+, and H-3(+) have been observed in a diffuse molecular cloud along a line of sight near W51 IRS2. We present the first chemical analysis that combines the
CH+(1-0) and 13CH+(1-0) absorption lines in the direction of massive star-forming regions
We report the detection of the ground-state rotational transition of the methylidyne cation CH+ and its isotopologue 13CH+ toward the remote massive star-forming regions W33A, W49N, and W51 with the
Comparative study of CH+ and SH+ absorption lines observed towards distant star-forming regions
Aims. The HIFI instrument onboard Herschel has allowed high spectral resolution and sensitive observations of ground-state transitions of three molecular ions: the methylidyne cation CH^+, its
A spectral line survey of the starless and proto-stellar cores detected by BLAST toward the Vela-D molecular cloud
Context. Starless cores represent a very early stage of the star forma tion process, before collapse results in the formation of a c entral protostar or a multiple system of protostars. Aims. We use


Cloud structure and physical conditions in star-forming regions from optical observations
We present high-resolution optical spectra (at ~0.6-1.8 km s-1) of interstellar CN, CH, CH+, Ca I, K I, and Ca II absorption toward 29 lines of sight in three star-forming regions, ρ Oph, Cep OB2,
H2 formation and excitation in the diffuse interstellar medium
We use far-UV absorption spectra obtained with FUSE towards three late B stars to study the formation and ex- citation of H2 in the diuse ISM. The data interpretation relies on a model of the
Ultra-high-resolution observations of the intrinsic line profiles of interstellar CH, CH+ and CN
Ultra-high-resolution (0.3 km s–1 FWHM) observations of interstellar CH and CH+ are presented for five southern stars (HD 110432, 152234, 152235, 152236 and 152270); CN spectra were also obtained for
Nonthermal Chemistry in Diffuse Clouds with Low Molecular Abundances
High-quality archival spectra of interstellar absorption from Ci toward nine stars, taken with the Goddard High Resolution Spectrograph on the Hubble Space Telescope, were analyzed. Our sample was
Comparative chemistry of diffuse clouds: II. CN, HCN, HNC, CH3CN& N2H^+
Using the Plateau de Bure interferometer, we observed the 3 mm absorption lines of CN, HCN and HNC from some of the diuse clouds which lie toward our well-studied sample of compact extragalactic
Kinematics and Chemistry of the Hot Molecular Core in G34.26+0.15 at High Resolution
We present high angular resolution (~1'') multitracer spectral line observations toward the hot molecular core (HMC) associated with G34.26+0.15 between 87 and 109 GHz. We have mapped emission from
Chemical transitions for interstellar C2 and CN in cloud envelopes
Observations were made of absorption from CH, C2, and CN toward moderately reddened stars in Sco, OB2, Ceo OB3, and Taurus/Auriga. For these directions, most of the reddening is associated with a
Nitrogen hydrides in interstellar gas - Herschel/HIFI observations towards G10.6-0.4 (W31C)
The HIFI instrument on board the Herschel Space Observatory has been used to observe interstellar nitrogen hydrides along the sight-line towards G10.6−0.4 in order to improve our understanding of the
We have observed six clouds along the line of sight toward W49A using the Submillimeter Wave Astronomy Satellite and several ground-based observatories. The ortho-H2O 110 → 101 and OH (1665 and 1667
Detection of interstellar NH towards ζ Ophiuchi by means of ultra-high-resolution spectroscopy
We have obtained an ultra-high-resolution (0.38 km s-l FWHM) spectrum of the R1(0) (3358.053 A) line of interstellar NH towards r Oph. These observations comprise the first detection of NH towards r