On the internal structure of starless cores

• DOI: 10.1051/0004-6361:20031704
• Publication Date: 2004-02-23T14:00:24Z
• Authors: M. Tafalla; P. C. Myers; P. Caselli; C. M. Walmsley
• Keywords: Isotopomers; Submillimeter Array

We have characterized the physical structure and chemical composition of two close-to-round starless cores in Taurus-Auriga, L1498 L1517B. Our analysis is based on high angular resolution observations at least transitions NH3, N2H+, CS, C34S, C18O, C17O, together with maps 1.2 mm continuum. For both cores, we derive radial profiles constant temperature turbulence, density distributions close to those non-singular isothermal spheres. Using these conditions a Monte Carlo radiative transfer model, abundance for all species model strong differentiation core interiors. According our models, NH3 increases toward centers by factor several 5) while N2H+ has over most cores. In contrast, C18O CS (and isotopomers) are strongly depleted interiors, likely due their freeze out onto grains densities few 104 cm-3. Concerning kinematics dense gas, find (in addition turbulence) pattern internal motions level 0.1 km s-1. These seem correlated asymmetries molecular depletion, interpret them as residuals contraction. Their distribution size suggest that formation occurs rather irregular manner time scale Myr. A comparison derived properties predicted supersonic turbulence models shows Taurus much more quiescent than representative predictions from models. appendices end paper present simple accurate approximation profile an (Bonnor-Ebert) sphere, Carlo-calibrated method gas kinetic temperatures using data.