Related papers: Early phases of star formation: testing chemical t…
Our main purpose is to estimate the effect of assuming uniform density on the line-of-sight in PDR chemistry models, compared to a more realistic distribution for which total gas densities may well vary by several orders of magnitude. A…
Constraining parameters such as the initial mass function high-mass slope and the frequency of type Ia supernovae is of critical importance in the ongoing quest to understand galactic physics and create realistic hydrodynamical simulations.…
We use a suite of hydrodynamics simulations of the interstellar medium (ISM) within a galactic disk, which include radiative transfer, a non-equilibrium model of molecular hydrogen, and a realistic model for star formation and feedback, to…
The dense, cold regions where high-mass stars form are poorly characterised, yet they represent an ideal opportunity to learn more about the initial conditions of high-mass star formation (HMSF), since high-mass starless cores (HMSCs) lack…
Isotopic ratios have been used as chemical diagnostics to investigate the origin of the material in the Solar System. We have determined the HCN, HNC, and N2H+ isotopic ratios and the chemical age in a large sample of 23 starless cores…
Infrared Dark Clouds (IRDCs), condensed regions of the ISM with high column densities, low temperatures and high masses, are suspected sites of star formation. Thousands of IRDCs have already been identified. To date, it has not been…
Molecular clouds, which harbor the birthplaces of stars, form out of the atomic phase of the interstellar medium (ISM). We aim to characterize the atomic and molecular phases of the ISM and set their physical properties into the context of…
We analyzed both HCN J=1-0 and HNC J=1-0 line profiles to study the inflow motions in different evolutionary stages of massive star formation: 54 infrared dark clouds (IRDCs), 69 high-mass protostellar object (HMPOs), and 54 ultra-compact…
Star-forming regions host a large and evolving suite of molecular species. Molecular transition lines, particularly of complex molecules, can reveal the physical and dynamical environment of star formation. We aim to study the large-scale…
We report a sample of 463 high-mass starless clump (HMSC) candidates within $-60\deg<l<60\deg$ and $-1\deg<b<1\deg$. This sample has been singled out from 10861 ATLASGAL clumps. All of these sources are not associated with any known…
\abridged The nuclei of active galaxies harbor massive young stars, an accreting central black hole, or both. In order to determine the physical conditions that pertain to molecular gas close to the sources of radiation, numerical models…
Star formation activity in molecular clouds is often found to be correlated with the amount of material above a column density threshold of $\sim 10^{22} \, {\rm cm^{-2}}$. Attempts to connect this column density threshold to a ${\it…
Chemical abundances and abundance ratios measured in galaxies provide precious information about the mechanisms, modes and time scales of the assembly of cosmic structures. Yet, the nucleogenesis and chemical evolution of elements heavier…
We compare observations of HI from the Very Large Array (VLA) and the Arecibo Observatory and observations of HCO$^+$ from the Atacama Large Millimeter/submillimeter Array (ALMA) and the Northern Extended Millimeter Array (NOEMA) in the…
We characterize the molecular environment of candidate massive young stellar objects (MYSOs) signposted by methanol masers. Single pixel observations of 10 transitions of HCO^+, CO and CS isotopomers were carried out, using the IRAM 30m…
We report the identification of a sample of potential High-Mass Starless Cores (HMSCs). The cores were discovered by comparing images of the fields containing candidate High-Mass Protostellar Objects (HMPOs) at 1.2mm and mid-infrared…
Dense molecular gas and star formation are correlated in galaxies. The effect of low metallicity on this relationship is crucial for interpreting observations of high redshift galaxies, which have lower metallicities than galaxies today.…
Massive infrared dark clouds (IRDCs) are considered to host the earliest stages of high-mass star formation. In particular, 70 $\mu$m dark IRDCs are the colder and more quiescent clouds. At a scale of about 5000 au using formaldehyde (H2CO)…
Peptide bonds (N-C=O) play a key role in metabolic processes since they link amino acids into peptide chains or proteins. Recently, several molecules containing peptide-like bonds have been detected across multiple environments in the…
We use archival ALMA observations of the HCN and CO $J=1-0$ transitions, in addition to the radio continuum at 93 GHz, to assess the relationship between dense gas, star formation, and gas dynamics in ten, nearby (U)LIRGs and late-type…