Understanding the formation of stars in galaxies is central to much of modern astrophysics.
However, a quantitative prediction of the star formation rate and the initial distribution of …

Cold dark clouds are nearby members of the densest and coldest phase in the Galactic
interstellar medium, and represent the most accessible sites where stars like our Sun are …

Molecular absorption and emission bands dominate the visible, infrared, and submillimeter
spectra of most objects with associated gas. These observations reveal a surprisingly rich …

Aims. Photodissociation by UV light is an important destruction mechanism for carbon
monoxide (CO) in many astrophysical environments, ranging from interstellar clouds to …

We present results of an extensive map** survey of N 2 H+(1–0) in about 60 low-mass
cloud cores already mapped in the NH 3 (1, 1) inversion transition line. The survey has been …

We present evidence that low-mass starless cores, the simplest units of star formation, are
systematically differentiated in their chemical composition. Some molecules, including CO …

We have undertaken a survey of N 2 H+ and N 2 D+ toward 31 low-mass starless cores
using the IRAM 30 m telescope. Our main objective has been to determine the abundance …

Aims. We aim to characterize and compare the molecular-line emission of three clouds
whose star-formation rates span one order of magnitude: California, Perseus, and Orion A …

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 …

The maps presented in Paper I are here used to infer the variation of the column densities of
HCO+, DCO+, N 2 H+, and N 2 D+ as a function of distance from the dust peak. These …