Related papers: Systematic Molecular Differentiation in Starless C…
We present new results on CO depletion in a sample of nearby pre-stellar cores, based on observations of the millimeter C17O and C18O lines and the 1.3 mm dust emission with the IRAM 30m telescope. In most cases, the distribution of CO is…
We have observed the HC3N (J=10-9) and N2H+ (J=1-0) lines toward the Vela C molecular clouds with the Mopra 22 m telescope to study chemical characteristics of dense cores. The intensity distributions of these molecules are similar to each…
Cold ($\sim$10 K) and dense ($\sim$10$^{5}$ cm$^{-3}$) cores of gas and dust within molecular clouds, known as starless and dynamically evolved prestellar cores, are the birthplaces of low-mass ($M$ $\leq$ few M$_\odot$) stars. As…
Pre-stellar cores represent a critical evolutionary phase in low-mass star formation. We aim to unveil the detailed thermal structure and density distribution of three early-stage cores, starless core L1517B, and prestellar core L694-2 and…
Sufficiently massive clumps of molecular gas collapse under self-gravity and fragment to spawn a cluster of stars that have a range of masses. We investigate observationally the early stages of formation of a stellar cluster in a massive…
To characterize the initial conditions for intermediate- to high-mass star formation, we observed two Infrared Dark Clouds (IRDCs) that remain absorption features up to 70mum wavelength, with the PdBI in the 3.23mm dust continuum as well as…
Context. The spatial distribution of molecules around starless cores is a powerful tool for studying the physics and chemistry governing the earliest stages of star formation. Aims. Our aim is to study the chemical differentiation in…
We present the results of a single-pointing survey of 207 dense cores embedded in Planck Galactic Cold Clumps distributed in five different environments ($\lambda$ Orionis, Orion A, B, Galactic plane, and high latitudes) to identify dense…
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…
Dense cloud cores present chemical differentiation due to the different distribution of C-bearing and N-bearing molecules, the latter being less affected by freeze-out onto dust grains. In this letter we show that two C-bearing molecules,…
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…
In the standard picture of isolated star formation, dense ``starless'' cores are formed out of magnetic molecular clouds due to ambipolar diffusion. Under the simplest spherical geometry, I demonstrate that ``starless'' cores formed this…
We have measured the deuterium fractionation (through the column density ratio N(N2D+)/N(N2H+)) and the CO depletion factor (ratio between expected and observed CO abundance) in a sample of 10 high-mass protostellar candidates, in order to…
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…
We selected 90 massive star-forming clumps with strong N2H+, HCO+, HCN, and HNC emission from the Millimetre Astronomy Legacy Team 90 GHz survey. We obtained Herschel data for all 90 sources and NRAO VLA Sky Survey data for 51 of them. We…
Aims: We aim to simulate radial profiles of molecular abundances and the gas temperature in cold and heavily shielded starless cores by combining chemical and radiative transfer models. Methods: A determination of the dust temperature in a…
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…
We study the origin of large abundances of complex organic molecules in the Galactic center (GC). We carried out a systematic study of the complex organic molecules CH3OH, C2H5OH, (CH3)2O, HCOOCH3, HCOOH, CH3COOH, H2CO, and CS toward 40 GC…
Molecular emission is a powerful tool for studying the physical and chemical structures of dense cores. The distribution and abundance of different molecules provide information on the chemical composition and physical properties in these…
We have performed a pointed survey of N2D+ 2-1 and N2D+ 3-2 emission toward 64 N2H+-bright starless and protostellar cores in the Perseus molecular cloud using the Arizona Radio Observatory Submillimeter Telescope and Kitt Peak 12 m…