Related papers: Dust opacity variations in the pre-stellar core L1…
Early dust grain growth in protostellar envelopes infalling on young discs has been suggested in recent studies, supporting the hypothesis that dust particles start to agglomerate already during the Class 0/I phase of young stellar objects…
Understanding planet formation requires to discern how dust grows in protoplanetary disks. An important parameter to measure in disks is the maximum dust grain size present. This is usually estimated through measurements of the dust opacity…
The project Galactic Cold Cores has made Herschel observations of interstellar clouds where the Planck satellite survey has located cold and compact clumps. The sources range from starless clumps to protostellar cores. We examine 116…
[Abridged] $Context.$ Pre-stellar cores are centrally concentrated starless cores on the verge of star formation and they represent the initial conditions for star and planet formation. Pre-stellar cores host an active organic chemistry and…
Exploring the structure and dynamics of cold starless clouds is necessary to understand the different steps leading to the formation of protostars. Because clouds evolve slowly, many of them must be studied in detail to pick up different…
Prior to star formation, pre-stellar cores accumulate matter towards the centre. As a consequence, their central density increases while the temperature decreases. Understanding the evolution of the chemistry and physics in this early phase…
Observations of dark cloud cores have been carried out in the mid-infrared using ISOCAM and in the far-infrared using ISOPHOT, both aboard the Infrared Space Observatory. The cores are in most cases detected in emission at 200 and 170…
Density profiles of isolated cores derived from thermal dust continuum emission rely on models of dust properties, such as mass opacity, which are poorly constrained. With complementary measures from near-infrared extinction maps, we can…
Starless cores represent the initial stage of evolution toward (proto)star formation, and a subset of them, known as prestellar cores, with high density (~ 10^6 cm^-3 or higher) and being centrally concentrated are expected to be embryos of…
Recent high-resolution studies of the L1544 protostellar core by Tafalla et al. and Williams et al. reveal the structure and kinematics of the gas. The observations of this prestellar core provide a natural test for theoretical models of…
With Planck and Herschel, we now have the spectral coverage and angular resolution required to observe dense and cold molecular clouds. As these clouds are optically thick at short wavelength but optically thin at long wavelength, it is…
We study the density structure of candidate contracting starless core L694-2 using 1.3 mm dust continuum observations from the IRAM Plateau de Bure Interferometer and the Berkeley-Illinois-Maryland Array, probing spatial scales from…
Light scattering at near-infrared wavelengths has been used to study the optical properties of the interstellar dust grains, but these studies are limited by the assumptions on the strength of the radiation field. On the other hand, thermal…
Pre-stellar cores represent the earliest stage of the star- and planet-formation process. By characterizing the physical and chemical structure of these cores we can establish the initial conditions for star and planet formation and…
Context. Using observations to deduce dust properties, grain size distribution, and physical conditions in molecular clouds is a highly degenerate problem. Aims. The coreshine phenomenon, a scattering process at 3.6 and 4.5 $\mu$m that…
To characterize the mechanisms of planet formation it is crucial to investigate the properties and evolution of protoplanetary disks around young stars, where the initial conditions for the growth of planets are set. Our goal is to study…
Our understanding of the physical and chemical structure of pre-stellar cores, the simplest star-forming sites, has significantly improved since the last IAU Symposium on Astrochemistry (South Korea, 1999). Research done over these years…
Observations carried out toward starless and pre-stellar cores have revealed that complex organic molecules are prevalent in these objects, but it is unclear what chemical processes are involved in their formation. Recently, it has been…
The maps presented in Paper I are here used to infer the variation of the column densities of HCO+, DCO+, N2H+, and N2D+ as a function of distance from the dust peak. These results are interpreted with the aid of a crude chemical model…
We wish to map the magnetic field geometry and to study the dust properties of the starless cloud, L1570, using multi-wavelength optical polarimetry and photometry of the stars projected on the cloud. We made R-band imaging polarimetry of…