The GALFA-HI Survey: Transition from HI to H2 Caught in Action in the Perseus Molecular Cloud

Type Conference Paper
Names Min-Young Lee, S. Stanimirovic, A. Leroy, K. Douglas, J. Di Francesco, S. Gibson, L. Knee, R. Plume, A. Begum, J. Grcevich, C. Heiles, E. Korpela, J. Peek, N. Pingel, M. Putman, D. Saul
Proceedings Title Bulletin of the American Astronomical Society
Conference Name American Astronomical Society, AAS Meeting #217, #241.02
Volume 43
Date January 1, 2011
Short Title The GALFA-HI Survey
URL http://adsabs.harvard.edu/abs/2011AAS...21724102L
Library Catalog NASA ADS
Abstract The conversion of atomic gas into molecular gas is a critical process for star formation. Yet, a deep understanding of fundamental agents that control the ratio of atomic to molecular gas in molecular clouds has not been achieved. Recently, Krumholz et al. (2009) provided theoretical predictions for the ratio of atomic to molecular gas in galaxies as a function of galactic properties (total gas column density and metallicity). We test the Krumholz's predictions on sub-parsec scales by investigating the ratio of atomic to molecular gas across the Perseus molecular cloud. We estimate the dust column density using the IRIS 60 and 100 micron maps and derive the H2 column density from the excess of infrared emission relative to the HI column density. Using the HI data from the GALFA-HI Survey, we derive the map of RH2 (H2 surface density / HI surface density) for Perseus. Our comparison of observational data with the Krumholz's predictions shows that the model reasonably well describes RH2 as a function of total gas column density even at sub-parsec scales. We compare RH2 for several star-forming and dark clouds in Perseus to investigate the role of interstellar radiation field in molecule formation. This research was partially funded by the NSF grant AST-0707679 and the Research Corporation for Science Advancement.
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