AAS 196th Meeting, June 2000
Session 26. The Galactic ISM: Observations and Modelling
Display, Tuesday, June 6, 2000, 10:00am-6:30pm, Empire Hall South

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[26.18] Small Scale Structure in the Taurus Molecular Cloud: OH, H2CO, and CO Observations Towards Six Extra-galactic Continuum Sources

R. P. Kleban, P. F. Goldsmith (Cornell University)

The results of a study of six small sites in the Taurus molecular cloud will be presented. Each site was chosen because it was in a dense region of molecular material, with a strong extra-galactic radio continuum source behind it. The OH 1667 MHz and 1665 MHz lines and the 4.8 GHz H2CO line were observed in absorption against the background continuum sources. Using the method described by Marscher et. al. (1993 ApJ {\bf419}, L101), the sources were observed on five separate occasions with the Arecibo Observatory 305 m telescope. The observations occurred every three months over a fifteen month period. Due to differential galactic rotation and the earth's motion around the sun, the line of sight toward the radio sources changed with respect to the cloud over that time. Changes in the line profiles with time probe cloud variations on a size scale of a few to 10s of AU.

The area around each source was mapped in emission in CO, C18O, and 13CO using the FCRAO 14 m telescope. This data has been combined with interferometry data from BIMA of 13CO and C18O emission for several of the sites, to model local cloud conditions such as density, temperature, and structure. Combining the absorption and emission line spectroscopy yields morphological information about cloud structure at a range of small scales.

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