Related papers: Observations of pre-stellar cores
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…
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,…
Pre-stellar cores are the basic unit for the formation of stars and stellar systems. The anatomy of the physical and chemical structures of pre-stellar cores is critical for understanding the star formation process. L1544 is a prototypical…
[Abridged] We present a molecular survey of the starless cores L1498 and L1517B. These cores have been selected for their relative isolation and close-to-round shape, and they have been observed in a number of lines of 13 molecular species…
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…
(Abridged) We present evidence that low-mass starless cores, the simplest units of star formation, are systematically differentiated in their chemical composition. Molecules including CO and CS almost vanish near the core centers, where the…
Prestellar cores exhibit a strong chemical differentiation, which is mainly caused by the freeze-out of molecules onto the grain surfaces. Understanding this chemical structure is important, because molecular lines are often used as probes…
The detection of complex organic molecules (COMs) toward cold sources such as pre-stellar cores (with T<10 K), has challenged our understanding of the formation processes of COMs in the interstellar medium. Recent modelling on COM chemistry…
[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…
Pre-stellar cores represent the initial conditions in the process of star and planet formation. Their low temperatures ($<$10 K) allow the formation of thick icy dust mantles, which will be partially preserved in the future protoplanetary…
We have characterized the physical structure and chemical composition of two close-to-round starless cores in Taurus-Auriga, L1498 and L1517B. Our analysis is based on high angular resolution observations in at least two transitions of NH3,…
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…
Pre-stellar cores are the first steps in the process of star and planet formation. However, the dynamical and chemical evolution of pre-stellar cores is still not well understood. We aim at estimating the central density of the pre-stellar…
Recent observations of the pre-stellar core L1544 and the younger starless core L1498 have revealed that complex organic molecules (COMs) are enhanced in the gas phase toward their outer and intermediate-density shells. Our goal is to…
We have studied the physical and chemical properties of a quiescent starless core L1521E with various molecular lines. It is found that there exists a compact dense core traced by the H^13CO^+, HN^13C, CCS, and HC_3N lines; their…
Prestellar cores are unique laboratories for studies of the chemical and physical conditions preceding star formation. We observed the prestellar core L1544 in the fundamental transition of ortho-H2D+ (1_1,0-1_1,1) at different positions…
Dense low mass cores in nearby clouds like Taurus and Auriga are some of the simplest sites currently forming stars like our Sun. Because of their simplicity and proximity, dense cores offer the clearest view of the different phases of star…
Both analytic and numerical radiative transfer models applied to high spectral resolution CS and N2H+ data give insight into the evolutionary state of L1551 MC. This recently discovered pre-protostellar core in L1551 appears to be in the…
In order to obtain a census of the pre-stellar and star-forming molecular cores, we have begun an unbiased survey in CS and N2H+ of the L1630 and L1641 molecular clouds. The use of these two molecular species enables us to quantify and…
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…