EPoS Contribution
EPoS Contribution
CCH in prestellar cores

Marco Padovani
Institut de Ciencies de l'Espai (CSIC-IEEC), Barcelona, Spain
The ethynyl radical CCH is a crucial intermediate in the interstellar chemistry leading to long chain carbon compounds and its ground state gives rise to non-negligible Zeeman splitting. These facts make it of interest to explore its abundance variations in nearby prestellar cores. In particular, it seems worthwhile to test for its presence or absence in nearby cores where CO appears to be depleted. CCH is also of interest because hyperfine and spin interactions cause the rotational transitions to split into as many as eleven components which can be observed simultaneously with modern autocorrelation spectrometers. This allows for a precise examination of the deviations from LTE in individual rotational levels and eventually an evaluation of the relative importance of collisional and radiative processes. We describe the results of CCH observations towards two prestellar cores (L1498 and CB246) which show a clear signature for non-LTE hyperfine populations, with a discussion of the prospects for measuring magnetic field strengths using CCH.
Caption: Dust emission at 1.3 mm, coloured map, superposed to the emission of CCH(1-0) (J',F' - J,F = 3/2,2 - 1/2,1), black contours, for the two observed prestellar cores. The star to the south of the NW emission peak of CB246 shows the presence of a bright infrared source (2MASS J23563433+5834043).
Collaborators:
C.M. Walmsley, INAF, Italy
M. Tafalla, OAN, Spain
D. Galli, INAF, Italy
H.S.P. Mueller, U Köln, Germany
Key publication

Suggested Session: Chemistry, Cores and Collapse, Magnetic Fields