Related papers: Chemical changes during star formation: high- vers…
Low-mass protostars form from condensations inside molecular clouds when gravity overwhelms thermal and magnetic supporting forces. The first phases of the formation of a solar-type star are characterized by dramatic changes not only in the…
We present 1D radiative transfer modelling of the envelopes of a sample of 18 low-mass protostars and pre-stellar cores with the aim of setting up realistic physical models, for use in a chemical description of the sources. The density and…
The physical and chemical properties of cold and dense molecular clouds are key to understanding how stars form. Using the IRAM 30 m and NRO 45 m telescopes, we carried out a Multiwavelength line-Imaging survey of the 70 $\mu$m dark and…
The physical structure of the envelopes around a sample of fourteen massive (1000-100,000 solar L) young stars is investigated on 100- 100,000 AU scales using maps and spectra in submillimeter continuum and lines of C17O, CS and H2CO. The…
Young Stellar Objects (YSO) are newly formed stars from molecular clouds. They stay close to where they were born and serve as good tracers to study gas and star formation. During cloud evolution, young massive stars can disrupt the…
Star-forming regions show a rich and varied chemistry, including the presence of complex organic molecules - both in the cold gas distributed on large scales, and in the hot regions close to young stars where protoplanetary disks arise.…
Star formation is a multi-scale, multi-physics problem ranging from the size scale of molecular clouds ($\sim$10s pc) down to the size scales of dense prestellar cores ($\sim$0.1 pc) that are the birth sites of stars. Several physical…
The complexity of physico-chemical models of star formation is increasing, with models that take into account new processes and more realistic setups. These models allow astrochemists to compute the evolution of chemical species throughout…
Low-mass dense cores represent the state of molecular gas associated with the earliest phases of low-mass star formation. Such cores are called "protostellar" or "starless," depending on whether they do or do not contain compact sources of…
Observations of dense molecular gas lie at the basis of our understanding of the density and temperature structure of protostellar envelopes and molecular outflows. We aim to characterize the properties of the protostellar envelope,…
Up to 90% of the chemical reactions during star formation occurs on ice surfaces, probably including the formation of complex organics. Only the most abundant ice species are however observed directly by infrared spectroscopy. This study…
The standard interstellar ratio of deuterium to hydrogen (D/H) atoms is $\sim 1.5 \times 10^{-5}$. However, the deuterium fractionation is in fact found to be enhanced, to different degrees, in cold, dark cores, hot cores around massive…
During the process of star formation, the dense gas undergoes significant chemical evolution leading to the emergence of a rich variety of molecules associated with hot cores and hot corinos. However, the physical and chemical conditions…
Aims. Our goals are to compare the CS, N2H+ and dust distributions in a representative sample of high-mass star forming dense cores and to determine the physical and chemical properties of these cores. Methods. We compare the results of…
We review the use of young low mass stars and protostars, or young stellar objects (YSOs), as tracers of star formation. Observations of molecular clouds at visible, infrared, radio and X-ray wavelengths can identify and characterize the…
We found that in regions of high mass star formation the CS emission correlates well with the dust continuum emission and is therefore a good tracer of the total mass while the N$_2$H$^+$ distribution is frequently very different. This is…
The onset of massive star formation is not well understood because of observational and theoretical difficulties. To find the dense and cold clumps where massive star formation can take place, we compiled a sample of high infrared…
Detailed radial/vertical structure modeling of observations of disks around Young Stellar Objects (YSOs) can provide information on the physical conditions and on the characteristics of the gas and dust in their interiors. We describe…
There is mounting evidence that the composition and structure of planetary systems are intimately linked to their birth environments. During the past decade, several spectral surveys probed the chemistry of the earliest stages of star…
Massive stars play an important role in shaping the structure of galaxies. Infrared dark clouds (IRDCs), with their low temperatures and high densities, have been identified as the potential birthplaces of massive stars. In order to…