Very Cold and Massive Cores near Isoss J18364-0221: Implications for the Initial Conditions of High-mass Star-formation

We report the discovery of two very cold and massive molecular cloud cores in the region ISOSS J18364-0221. The object has been identified by a systematic search for very early evolutionary stages of high-mass stars using the 170μm ISOPHOT Serendipity Survey (ISOSS). Submm continuum and molecular line measurements reveal two compact cores within this region. The first core has a temperature of 16.5K, shows signs of ongoing infall and outflows, has no NIR or MIR counterpart and is massive enough (M ∼ 75M⊙) to form at least one O star with an associated cluster. It is therefore considered a candidate for a genuine high-mass protostar and a high-mass analog to the Class 0 objects. The second core has an average gas and dust temperature of only ∼ 12K and a mass of M ∼ 280M⊙. Its temperature and level of turbulence are below the values found for massive cores so far and are suggested to represent the initial conditions from which high-mass star formation occurs. Subject headings: Stars: formation — ISM: dust, extinction — ISM: kinematics and dynamics — ISM: clouds — ISM: individual objects: ISOSS J18364-0221— Astronomical data bases: ISO data base