Herschel observation of C3 in star forming regions

Conference poster, 2011

We present spectrally resolved observations of triatomic carbon (C3) in several ro-vibrational transitions between the vibrational ground state and the low-energy ν2 bending mode at frequencies above 1.6 THz using HIFI onboard Herschel, towards several Galactic star forming regions including W31C, W49N, DR21(OH), W33A and W51. These observations have been performed as part of the Herschel key programme PRISMAS. C3 lines arising from the warm envelopes surrounding the hot cores associated with these star forming regions are detected in absorption. We shall present results of detailed radiative transfer models in which the C3 lines are excited by FIR pumping by the dust continuum.