Large-scale structure of the molecular gas in Taurus revealed by high linear dynamic range spectral line mapping

We report the results of a 100 deg(2) survey of the Taurus molecular cloud region in (CO)-C-12 and (CO)-C-13 J = 1 -> 0. The image of the cloud in each velocity channel includes similar or equal to 3 x 10(6) Nyquist-sampled pixels on a 20 '' grid. The high sensitivity and large spatial dynamic range of the maps reveal a very complex, highly structured cloud morphology, including filaments, cavities, and rings. The axes of the striations seen in the (CO)-C-12 emission from relatively diffuse gas are aligned with the direction of the magnetic field. We have developed a statistical method for analyzing the pixels in which (CO)-C-12 but not (CO)-C-13 is detected, which allows us to determine the CO column in the diffuse portion of the cloud, as well as in the denser regions in which we detect both isotopologues. Using a column-density-dependent model for the CO fractional abundance, we derive the mass of the region mapped to be 2.4 x 10(4) M-circle dot, more than twice as large as would be obtained using a canonical fixed fractional abundance of (CO)-C-13, and a factor of 3 greater than would be obtained considering only the high column density regions. We determine that half the mass of the cloud is in regions having column density below 2.1 x 10(21) cm(-2). The distribution of young stars in the region covered is highly nonuniform, with the probability offinding a star in a pixel with a specified column density rising sharply for N(H-2) = 6 x 10(21) cm(-2). We determine a relatively low star formation efficiency (mass of young stars/mass of molecular gas), between 0.3% and 1.2%, and an average star formation rate during the past 3 Myr of 8; 10(-5) stars yr(-1).