Research Information System
5th Zermatt ISM Symposium Conditions and Impact of Star Formation: New Results with Herschel and Beyond, Zermatt, Switzerland, 19 - 24 September 2010, vol.52, pp.313-314, (Full Text)
Herschel-HIFI observations of high-J lines (up to J(u) = 10) of (CO)-C-12, (CO)-C-13 and (CO)-O-18 are presented toward three deeply embedded low-mass protostars in NGC 1333. The observations show several energetic components including shocked and quiescent gas. Radiative transfer models are used to quantify the (CO)-O-18 envelope abundance which require a jump in the abundance at an evaporation temperature, T-ev similar to 25 K, providing new direct evidence of a CO ice evaporation zone around protostars. The abundance in the outermost part of the envelope, X-0, is within the canonical value of 2 x 10(-4); however the inner abundance, X-in, is found around a factor of 3-5 lower than X-0.