Seminar in Interstellar Matter

Stars form in the densest parts of molecular clouds, so-called prestellar cores. However, the formation and spatial distribution of prestellar cores in different kinds of molecular clouds is far from well-known due to the lack of an "all-sky" census. The important connection between core formation and the hierarchical fragmentation of molecular clouds remains obscure. Now, the Planck telescope has provided us with an unprecedented sample of "all-sky" pre-stellar object candidates. Planck cold clumps correspond to the coldest portion of the ISM where stars form, and can be used to characterize the earliest stages of star formation. In order to make significant progress in understanding the early evolution of molecular clouds and dense cores in a wide range of Galactic environments, we will carry out an unbiased "all-sky" survey of 2000 Planck cold clumps in J=1-0 of CO/13CO survey with TRAO 14-m telescope and 850 micrometer continuum survey with the JCMT/SCUBA-2. Through this extensive survey, we will study how dense cores form and how star formation varies as a function of environment, the universality of filaments in the cold ISM and their roles in generating dense cores, the existence of a density threshold for dense core formation, how dust properties change in different environments and, how dust properties affect the chemical evolution of dense cores. We are actively developing follow-up surveys/observations (SMT, KVN, FAST, NRO 45-m, SMA) for these legacy surveys, which will allow us to deepen the investigation of the dense core or star formation in widely different environments at their earliest evolutionary phases. Our survey will also provide a unique legacy database for such studies with other instruments, especially with ALMA.

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