We present a detailed study of the ionization fraction of the Barnard 68 pre-stellar core, using millimeter HCO and DCO lines observations. These observations are compared to the predictions of a radiative transfer model coupled to a chemical network that includes depletion on grains and gas phase deuterium fractionation. Together with previous observations and modelling of CO and isotopologues...

We report on the first detection in space of fulminic acid, HCNO. This isomer of HNCO has been observed in three starless cores, B1, L1544 and L183, and in the low mass star forming region L1527 with a measured abundance ratio of HNCO/HCNO between 40-70. However, HCNO was not detected towards the direction of the cyanopolyyne peak of TMC-1 or towards the Orion Hot Core region. The derived HNCO/...

We present the results of imaging spectroscopy of the reflection nebula vdB 133, obtained with the infrared camera and circular variable filter wheel on the Infrared Space Observatory (ISO). Our observations reveal the infrared emission features (IEFs), at 6.2, 7.7, 8.6, 11.3, and 12.7 μm, and associated 5 – 15 μm continuum emission. The stellar system illuminating vdB 133 has the lowest ratio ...

Cepheus E is the site of an exceptional example of a protostellar outflow with a very young dynamical age and extremely high near infrared luminosity. We combine molecular spectroscopic data from the submillimeter to the near infrared in order to interpret the rotational excitation of CO and the ro-vibrational excitation of H2. We conclude that C-type shocks with a paraboloidal bow shock geomet...

We show in this paper why molecular millimeter absorption line searches in DLAs have been unsuccessful. We use CO emission line maps of local galaxies to derive the H2 column density distribution function f(NH2) at z = 0. We show that it forms a natural extension to f(NHI): the H2 distribution exceeds f(NHI) at NH ≈ 10 cm and exhibits a power law drop-off with slope ∼ −2.5. Approximately 97% of...

Using the IRAM 30 m telescope, a mapping survey in optically thick and thin lines was performed towards 46 high mass star-forming regions. The sample includes UC Hii precursors and UC Hii regions. Seventeen sources are found to show ”blue profiles”, the expected signature of collapsing cores. The excess of sources with blue over red profiles ([Nblue – Nred]/Ntotal) is 29% in the HCO + J=1–0 lin...

We present the results of a search for molecular gas emission via the CO line in the far outer disk of the nearby spiral, NGC 6946. The positions targeted were chosen to lie on or near previously-identified outer disk HII regions. Molecular gas was clearly detected out to 1.3 R25, with a further tentative detection at 1.4 R25. The CO detections show excellent agreement with the HI velocities an...

We calculate the evolution of molecular line profiles of HCO and CO toward a dense core that is forming inside a magnetized turbulent molecular cloud. Features of the profiles can be affected more significantly by coupled velocity and abundance structures in the outer region than those in the inner dense part of the core. The velocity structure at large radii is dominated by a turbulent flow ne...

Many present-day galaxies are known to harbor supermassive, ≥ 10 M⊙, black holes. These central black holes must have grown through accretion from less massive seeds in the early universe. The molecules CO and H2 can be used to trace this young population of accreting massive black holes through the Xray irradiation of ambient gas. The X-rays drive a low-metallicity ion-molecule chemistry that ...

We have investigated the presence of dense gas toward the radio source Cen A by looking at the absorption of the HCO and HCN (3-2) lines in front of the bright continuum source with the Submillimeter Array. We detect narrow HCO (3-2) absorption, and tentatively HCN (3-2), close to the systemic velocity. For both molecules, the J = 3 − 2 absorption is much weaker than for the J = 1− 0 line. From...