Cecilia Ceccarelli

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Ceccarelli et al. (1998) recently reported the detection of D 2 CO in the low–luminosity protostar IRAS 16293– 2422. Using the data available at the time, they found that the abundance of D 2 CO might be as high as 1/10th that of its hy-drogenated counterpart H 2 CO. Here we describe and analyse new multi–transition observations of D 2 CO, HDCO, H 2 CO, and(More)
Sun like stars are born from the collapse of fragment of molecular clouds. During the first embedded phase (the so called class 0/1), the protostar is surrounded by a collapsing envelope, whose physical and chemical structure would set up the initial conditions of the proto-stellar disk which may eventually form planets. In this contribution , we show how(More)
Context. The high degree of deuteration observed in some prestellar cores depends on the ortho-to-para H 2 ratio through the H + 3 fractionation. Aims. We want to constrain the ortho/para H 2 ratio across the L183 prestellar core. This is mandatory to correctly describe the deuter-ation amplification phenomenon in depleted cores such as L183 and to relate(More)
We report observations of the expected main S-bearing species (SO, SO2 and H2S) in the low-mass star forming region L1689N. We obtained large scale (∼ 300 ′′ x200 ′′) maps of several transitions from these molecules with the goal to study the sulphur chemistry, i.e. how the relative abundances change in the different physical conditions found in L1689N. We(More)
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 physical structure but also in the chemical composition. Since Protostars and Planets IV (e.g., Langer et al., 2000),(More)
This work was carried out with using the Caltech Submillimeter Observatory and presents the observational study of HDS and D 2 S towards a sample of Class 0 sources, and dense cores. We report the first detection of doubly deuterated hydrogen sulfide (D 2 S) in two dense cores and analyze the chemistry of these molecules aiming to help understand the(More)
Single-dish spectra and interferometric maps of (sub-)millimeter lines of H 18 2 O and HDO are used to study the chemistry of water in eight regions of high-mass star formation. The spectra indicate HDO excitation temperatures of ∼110 K and column densities in an 11 ′′ beam of ∼2×10 14 cm −2 for HDO and ∼2×10 17 cm −2 for H2O, with the N (HDO)/N (H2O) ratio(More)
We have detected the 372 GHz line of ortho–H2D + towards the pre–stellar core L1544. The strongest emission (T mb ∼ 1 K) occurs at the peak of the millimeter continuum emission, while measurements at offset positions indicate that H2D + is confined within ∼ 20 ′′ , where CO is highly depleted. The derived H2D + abundance of ∼10 −9 is comparable with(More)
A (sub-)millimeter line and continuum study of the class I protostar Elias 29 in the ρ Ophiuchi molecular cloud is presented, whose goals are to understand the nature of this source, and to locate the ices that are abundantly present along this line of sight. Within 15–60 ′′ beams, several different components contribute to the line emission. Two different(More)
The BASECOL2012 database is a repository of collisional data and a web service within the Virtual Atomic and Molecular Data Centre (VAMDC, http://www.vamdc.eu). It contains rate coefficients for the collisional excitation of rotational, ro-vibrational, vi-brational, fine, and hyperfine levels of molecules by atoms, molecules, and electrons, as well as(More)