Dr. Paul Goldsmith will carry out a major study of the Taurus molecular cloud complex. It will result in the largest images in 12CO and 13CO of a molecular cloud yet obtained. This project will also produce the first fully sampled high angular resolution map of atomic hydrogen in the 100 square degree region. The combination of the atomic and molecular data sets will, in conjunction with existing data on the dust distribution and young stars in Taurus, provide a unique tool for studying key aspects of the life cycle of molecular clouds and star formation. Acquiring the data to address these important questions is only possible due to recent developments in radio astronomical imaging technology. The molecular maps will be obtained using the Five College Radio Astronomy Observatory 13.7m telescope and 32 element Sequoia focal plane array: observing time has already been allocated. The HI data will be obtained using the 305m Arecibo telescope and the 7 element dual polarization ALFA focal plane array system. Prior to the availability of these instruments which provide an order of magnitude increase in mapping speed, it was not realistic to cover the required solid angle with the angular resolution needed to be sensitive to structure over a range of scales exceeding 100:1. The greatly enhanced capability permits this project to address the following key questions. 1. The relationship between the atomic and molecular components of Taurus, including the evolutionary history of the region, will be addressed by comparing the hydrogen emission and absorption line profiles and column densities, and by determining the ages of cloud cores from their residual atomic gas content; 2. The role of turbulence in dark cloud complexes -- both in the atomic/molecular transition and in the formation of new stars -- will be studied by the Dr. Goldsmith and collaborators through identification of critical scales for turbulent support based on Principal Component Analysis; 3. Critical parameters for star formation, including the threshold of column density and/or density, the association between molecular clouds and stars, and the role of large scale processes versus local effects in star formation will be identified; 4. The impact of young stars on molecular clouds and subsequent star formation will be evaluated by carrying out a complete census of molecular outflows, the energy that they have returned to molecular clouds, and their effect on cloud structure.
This work will have an impact on a wide range of areas in astrophysics and star formation research, especially (1) numerical simulations of atomic and molecular cloud hydrodynamics including the transition between these two key phases; (2) time dependent astrochemistry based on gas phase reactions and grain surface formation of molecular hydrogen; (3) the overall energetics of molecular clouds including dissipation and regeneration of turbulence. This work will integrate research and teaching. Various portions of the data will be ideal for investigation by undergraduate students. Inasmuch as the formation of solar type stars is of considerable interest to the public, and that this kind of mapping project really does produce images to which people can relate, it is ideally suited for both talks and to be the focus of exhibits being contemplated for local science education facilities.
