Related papers: Limits on chemical complexity in diffuse clouds: s…
Based on measurements with the Effelsberg 100-m telescope, a multi-line study of molecular species is presented toward the south-western source of the gravitational lens system PKS 1830-211, which is by far the best known target to study…
In the Halo21 absorption modeling challenge we generated synthetic absorption spectra of the circumgalactic medium (CGM), and attempted to estimate the metallicity, temperature, and density (Z, T, and nH) of the underlying gas using…
We investigate the correlation between OH and H2 column densities in diffuse Galactic clouds, in order to identify potential molecular tracers of interstellar H2. For this, we analyse near-UV spectra extracted from the ESO/VLT archives…
We discuss the interstellar absorption from many atomic and molecular species seen in high-resolution $HST$/STIS UV and high-S/N optical spectra of the moderately reddened B3-5~V star HD~62542. This remarkable sight line exhibits both very…
We report new observations of the fundamental $J=1-0$ transition of HCl (at 625.918GHz) toward a sample of 25 galactic star-forming regions, molecular clouds, and evolved stars, carried out using the Caltech Submillimeter Observatory.…
Surprisingly large column densities of H3+ have been detected using infrared absorption spectroscopy in seven diffuse cloud sightlines (Cygnus OB2 12, Cygnus OB2 5, HD 183143, HD 20041, WR 104, WR 118, and WR 121), demonstrating that H3+ is…
We present the detection analysis of a diffuse molecular cloud at z$_{abs}$=2.4636 towards the quasar SDSS J1513+0352(z$_{em}\,\simeq$ 2.68) observed with the X-shooter spectrograph(VLT). We measure very high column densities of atomic and…
Complex organic molecules, such as propylene (CH3CHCH2), are detected in molecular clouds (such as TMC1) with high fractional abundances (~2.10^{-9}, relative to hydrogen) that cannot be explained by gas-phase chemical reactions under…
We investigated the chemical evolution of HC3N in six dense molecular clouds, using archival available data from the Herschel infrared Galactic Plane Survey (Hi-GAL) and the Millimeter Astronomy Legacy Team Survey at 90 GHz (MALT90). Radio…
We report the results of a sensitive search for the 443.952902 GHz $J=1-0$ transition of the LiH molecule toward two interstellar clouds in the Milky Way, W49N and Sgr B2 (Main), that has been carried out using the Atacama Pathfinder…
Context. High latitude molecular clouds (hereafter HLMCs) permit the study of interstellar gas dynamics and astrochemistry with good accuracy due to their proximity, generally clear lines of sight, and lack of internal star-forming activity…
We have mapped 27 massive star-forming regions associated with water masers using three dense gas tracers: HC3N 10-9, HNC 1-0 and C2H 1-0. The FWHM sizes of HNC clumps and C2H clumps are about 1.5 and 1.6 times higher than those of HC3N,…
We present the discovery in TMC-1 of vinyl acetylene, CH2CHCCH, and the detection, for the first time in a cold dark cloud, of HCCN, HC4N, and CH3CH2CN. A tentative detection of CH3CH2CCH is also reported. The column density of vinyl…
Recent detections of complex organic molecules in dark clouds have rekindled interest in the astrochemical modeling of these environments. Because of its relative closeness and rich molecular complexity, TMC-1 has been extensively observed…
Almost all the physics of star formation critically depends on the number density of the molecular gas. However, the methods to estimate this key property often rely on uncertain assumptions about geometry, depend on overly simplistic…
It is important to understand the origin of molecular line intensities and chemical composition in the molecular-cloud scale in the Galactic sources because it serves as a benchmark to compare with the chemical compositions of extragalactic…
Observations of diffuse clouds showed that they contain a number of simple hydrocarbons (e.g. CH, C$_2$H, (l- and c-)C$_3$H$_2$, and C$_4$H) in abundances that may be difficult to understand on the basis of conventional gas-phase chemical…
We present evidence of 6.7 GHz methanol (CH3OH)~and 4.8 GHz formaldehyde (H2CO) absorption towards the Galactic Center (GC) point-source `N3'. Both absorption features are unresolved and spatially aligned with N3. The 6.7 GHz CH3OH contains…
We have constructed three-dimensional models for the equilibrium abundance of molecular hydrogen within diffuse interstellar clouds of arbitrary geometry that are illuminated by ultraviolet radiation. The position-dependent photo-…
%context More gas is inferred to be present in molecular cloud complexes than can be accounted for by HI and CO emission, a phenomenon known as dark neutral medium (DNM) or CO-dark gas for the molecules. %aims To see if molecular gas can be…