Related papers: L1521E: A Starless Core in the Early Evolutionary …

We present here findings for C18O depletion in eight starless cores in Taurus: TMC-2, L1498, L1512, L1489, L1517B, L1521E, L1495A-S, and L1544. We compare observations of the C18O J=2-1 transition taken with the ALMA prototype receiver on…

We detected carbon-chain molecules (CCMs) HC2n+1N (n=1-3) and C3S in Ku band as well as {high-energy excitation lines including C4H N=9-8, J=17/2-15/2, 19/2-17/2, and CH3CCH J=5-4, K=2 in the 3 mm band toward a starless core called the…

I review the basic processes that may be used to develop a chemical evolutionary sequence for low-mass starless cores. I highlight observational results from the Arizona Radio Observatory-Green Bank Survey. Observations were performed with…

Context. Low-mass star-forming cores differ from their surrounding molecular cloud in turbulence, shape, and density structure. Aims. We aim to understand how dense cores form out of the less dense cloud material by studying the connection…

Aims. The purpose of this study is to investigate the distributions of the isomeric molecules HCN and HNC and estimate their abundance ratio in the protostellar core Cha-MMS1 located in Chamaeleon {\sc i}. Methods. The core was mapped in…

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…

We present results of mapping observations of the DNC, HN^13C, and H^13CO^+ lines (J=1-0) toward 4 nearby dark cloud cores, TMC-1, L1512, L1544, and L63, along with observations of the DNC and HN^13C lines (J=2-1) toward selected positions.…

The chemical evolution of pre-stellar cores during their transition to a protostellar stage is not yet fully understood. Detailed chemical characterizations of these sources are needed to better define their chemistry during star formation.…

We present results from the Spitzer Space Telescope and molecular line observations of 9 species toward the dark cloud L43. The Spitzer images and molecular line maps suggest it has a starless core and a Class I protostar evolving in the…

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…

In the centre of pre-stellar cores, deuterium fractionation is enhanced due to the low temperatures and high densities. Therefore, the chemistry of deuterated molecules can be used to study the earliest stages of star formation. We analyse…

We report molecular line observations, made with ASTE and SEST, and dust continuum observations at 0.87 mm, made with APEX, towards the cold dust core G305.136+0.068. The molecular observations show that the core is isolated and roughly…

We have undertaken a survey of N2H+ and N2D+ towards 31 low-mass starless cores using the IRAM 30m telescope. Our main objective has been to determine the abundance ratio of N2D+ and N2H+ towards the nuclei of these cores and thus to obtain…

Spitzer Space Telescope observations of a point-like source, L1014-IRS, close to the dust peak of the low-mass dense core L1014 have questioned its starless nature. The presence of an object with colors expected for an embedded protostar…

We have compared molecular line emission to dust continuum emission and modeled molecular lines using Monte Carlo simulations in order to study the depletion of molecules and the ionization fraction in three preprotostellar cores, L1512,…

We imaged two starless molecular cloud cores, TUKH083 and TUKH122, in the Orion A giant molecular cloud in the CCS and ammonia (NH$_3$) emission with the Very Large Array. TUKH122 contains one NH$_3$ core "TUKH122-n," which is elongated and…

OH231.8+4.2 is a well studied O-rich CSE around an intermediate-mass evolved star that displays bipolar molecular outflows accelerated up to 400 km/s. OH231 also presents an exceptional molecular richness probably due to shock-induced…

The physical structure of hot molecular cores, where forming massive stars have heated up dense dust and gas, but have not yet ionized the molecules, poses a prominent challenge in the research of high-mass star formation and…

We observed the $J=5-4$ rotational lines of the normal species and three $^{13}$C isotopologues of HC$_{3}$N at the 45 GHz band toward two low-mass starless cores, L1521B and L134N (L183), using the Nobeyama 45 m radio telescope in order to…

N2H+ observations of molecular cloud cores in Taurus with the Nobeyama 45 m radio telescope are reported. We compare ``cores with young stars'' with ``cores without young stars''. The differences in core radius, linewidth, and core mass are…