PI: Craig A. Kulesa, University of Arizona, firstname.lastname@example.org
Address: Steward Observatory, 933 N. Cherry Ave., Tucson, AZ 85721, USA
CoI: John H. Black, Onsala Space Observatory
Title: Direct Measurement of Cold H_2 and CO in the \rho Ophiuchi Star Forming Region
Abstract: High-resolution infrared spectroscopy provides a powerful probe of the physical conditions, abundances, chemistry and distribution of molecular material in interstellar clouds. The dominant form of hydrogen in cool, dense clouds is H_2; indeed, it comprises almost half of the normal interstellar matter in the Galaxy. However, its symmetric properties leave it with no observable emission-line spectrum in the vast majority of the cold and dark environments where it dominates. However, through a weak electric-quadrupole absorption line spectrum, the pivotal H_2 molecule can be detected \bf directly and compared along the same pencil-beam line of sight with the abundance of its most commonly cited surrogate, CO. The excitation and abundances of these two species are being firmly established by this group via previous observations with Phoenix at Kitt Peak. With the improved sensitivity and high resolution of Phoenix at Gemini, coarse ``mapping'' of many lines of sight through a single cloud can now be performed. Comparison with [sub]millimeter spectroscopy mapping over the same region will provide a direct test of over 30 years of CO measurements at mm-wavelengths, and will calibrate the technique of near-infrared extinction as a probe of the physical structure of molecular clouds. We propose to test these concepts for the \rho Ophiuchi molecular cloud, where these results will have immediate impact upon extensive existing ground- and space- based infrared and submillimeter observations, such as those from MIPS and IRS on SIRTF and FLAMINGOS at Kitt Peak and the MMT.
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