The COMPLETE study of dense cores with the GBT: pointed observations and maps
Harvard-Smithsonian Center for Astrophysics
In the past years, dust continuum surveys of molecular clouds have been the most successful approach to find dense cores. With the planned and on-going surveys (which are deeper and/or with an even better coverage) a larger and more unbiased sample of dense cores is expected. However, to derive the mass a temperature has to be assumed and no information about the dense cores kinematic is obtained, and therefore only from these observations we can not determine if the cores are bound. Ammonia (NH3) is a very good molecule to study dense cores, because we can derive the temperature and line-width in regions with high-density (it does not deplete onto dust grains as CO and isotopologues), and therefore, it is a very good complement to the dust continuum observations.
In this talk, I will present the results of two dense cores studies carried out by the COMPLETE Survey using the 100-meters Green Bank Telescope (GBT):
1) We have finished a survey of pointed observations with the GBT (100-m) towards *all* the known cores in the Perseus Molecular Cloud in NH3(1,1), NH3(2,2) and CCS (2-1). From these observations we have determined column densities, temperatures and line-widths. We perform a comparison of the physical parameters (temperatures, abundances and line-widths) between starless-vs-starred and clustered-vs-isolated cores.
2) We have also performed a follow-up study of two regions (IC348-mm and L1448), where we have completed large area maps (~100 arcmin2 and a ~30' beam). We will also present maps of the derived physical parameters (column densities, temperatures and line-widths). We compare the NH3 emission with the c2d Bolocam map (because the Bolocam angular resolution is almost identical to the GBT beam). What are the physical properties of the inter-core gas?
These surveys are part of the new generation of molecular line surveys that covers a complete cloud in high density tracers. I will focus on what we can learn from these surveys and how to use the current results to improve the planning of follow-up observations (pointing and mapping), specially regarding the new K-band array that will be available at the GBT in a few years.