[81.25] Structure of the Taurus Molecular Cloud Complex

AAS 207th Meeting, 8-12 January 2006
Session 81 ISM: From Dark to Blinded
Poster, Tuesday, 9:20am-6:30pm, January 10, 2006, Exhibit Hall

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[81.25] Structure of the Taurus Molecular Cloud Complex

P. Goldsmith (JPL), Y. Tang (Cornell Univ.), M. Heyer, G. Narayanan (Univ. Mass.), R. Snell (Univ. Mass), C. Brunt (Univ. Exeter), D. Li (JPL)

We report the initial results of a large-scale project mapping the Taurus molecular cloud complex. We have covered a 21 by 28 pc region (92 sq. deg.) using the FCRAO 14m telescope in ¹²CO and ¹³CO. Each map comprises 3.2x10⁶ Nyquist-sampled pixels with spatial resolution 0.03 pc. The rms noise is less than 0.75 K for the ¹²CO and less than 0.33 K for the ¹³CO in 0.1 km s^-1 channels.

The observations reveal an astonishing amount of structure in the spatial distribution and kinematics of the gas. There are several prominent ring-like features that have high contrast between central and peripheral column density. There are no sources which can plausibly be identified as responsible for emptying these regions of molecular gas. Several well-known dense regions are clearly delineated, including the molecular ring which contains TMC-1 and the filament including L1495. Overall, the dense regions of the cloud complex appear to be comprised of a network of filamentary features which are visible in ¹²CO as well as ¹³CO.

The edges of the dense regions are fuzzy, with the boundaries dominated by cilia-like features, which are generally aligned with the direction of the local magnetic field inferred from polarization measurements of background stars. Over a significant fraction of the area mapped the ¹³CO emission is not readily visible in individual spectra, but when spectra are averaged, emission from this species is found at a level of about 0.15 K. The ¹²CO is about an order of magnitude stronger, with integrated area approximately 20 times as great. Thus, there is a considerable amount of low column density molecular material which is traced by far-infrared dust emission. It is also striking that this material appears highly filamentary, with the filaments again being aligned with the local magnetic field direction.

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