Open AccessThe initial conditions of isolated star formation ‐‐ III. Millimetre continuum mapping of pre‐stellar cores
Author(s) -
WardThompson D.,
Motte F.,
André P.
Publication year - 1999
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1999.02412.x
Subject(s) - physics , james clerk maxwell telescope , astrophysics , star formation , molecular cloud , bolometer , protostar , young stellar object , millimeter , ambipolar diffusion , telescope , astronomy , galaxy , stars , optics , plasma , quantum mechanics , detector
We present the results of 1.3‐mm continuum mapping observations of eight pre‐stellar cores, taken with the IRAM 30‐m telescope equipped with the 19‐channel MPIfR bolometer array. The new 1.3‐mm data, which were obtained in the `on‐the‐fly' mapping mode, have higher angular resolution and sensitivity than previous surveys, reaching an rms noise level of ∼ 3‐‐9 mJy per 13‐arcsec beam. The present study supports the conclusions of our previous James Clerk Maxwell Telescope (JCMT) survey and suggests that, in contrast with some theoretical predictions, most pre‐stellar cores have flat inner density gradients that only approach ρ (r) ∝ r ‐2 beyond a few thousand au. Several of the cores have a filamentary‐like morphology and are apparently fragmented in a small number (∼ 2‐‐4) of subclumps. This implies that the initial conditions for protostellar collapse depart significantly from a singular isothermal sphere. We also note quantitative disagreement in time‐scales with published ambipolar diffusion models for the quasi‐static evolution of molecular cloud cores under the influence of a uniform magnetic field. We speculate that turbulent processes might help to explain our observations.