THE RELATION BETWEEN GAS AND DUST IN THE TAURUS MOLECULAR CLOUD

By J. Pineda, Paul F. Goldsmith, N. Chapman, R. Snell, Di Li, L. Cambrésy, C. Brunt. 2010

158 citations recorded by the source corpus.

We report a study of the relation between dust and gas over a 100 deg2 area in the Taurus molecular cloud. We compare the H2 column density derived from dust extinction with the CO column density derived from the 12CO and 13CO J = 1 → 0 lines. We derive the visual extinction from reddening determined from 2MASS data. The comparison is done at an angular size of 200″ corresponding to 0.14 pc at a distance of 140 pc. We find that the relation between visual extinction AV and N(CO) is linear between AV ≃ 3 and 10 mag in the region associated with the B213-L1495 filament. In other regions, the linear relation is flattened for AV≳ 4 mag. We find that the presence of temperature gradients in the molecular gas affects the determination of N(CO) by ∼30%–70% with the largest difference occurring at large column densities. Adding a correction for this effect and accounting for the observed relation between the column density of CO and CO2 ices and AV, we find a linear relationship between the column of carbon monoxide and dust for observed visual extinctions up to the maximum value in our data ≃23 mag. We have used these data to study a sample of dense cores in Taurus. Fitting an analytical column density profile to these cores we derive an average volume density of about 1.4 × 104 cm−3 and a CO depletion age of about 4.2 × 105 yr. At visual extinctions smaller than ∼3 mag, we find that the CO fractional abundance is reduced by up to two orders of magnitude. The data show a large scatter suggesting a range of physical conditions of the gas. We estimate the H2 mass of Taurus to be about 1.5 × 104 M☉, independently derived from the AV and N(CO) maps. We derive a CO integrated intensity to H2 conversion factor of about 2.1 × 1020 cm−2 (K km s−1)−1, which applies even in the region where the [CO]/[H2] ratio is reduced by up to two orders of magnitude. The distribution of column densities in our Taurus maps resembles a log-normal function but shows tails at large and low column densities. The length scale at which the high column density tail starts to be noticeable is about 0.4 pc.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/2cce244e45e1ed0d257ef58362f91e4e06160e0e

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Citations in the corpus

The CO-to-H2 Conversion Factor (2013, background): “In the highest resolution studies of the Large Magellanic Cloud (LMC) to date, Israel et al. (2003), Hughes et al. (2010), Wong et al. (2011), and Pineda et al. (2010) all find XCO,20 ≈ 4.”
Star Formation in the Milky Way and Nearby Galaxies (2012, methodology): “A recent, careful study of CO and 13CO toward the Taurus molecular cloud shows that N(CO) traces AV up to 10 mag in some regions but only up to 4 mag in other regions, and other issues cause problems below AV = 3 mag (Pineda et al. 2010b).”
ISM MASSES AND THE STAR FORMATION LAW AT Z = 1 TO 6: ALMA OBSERVATIONS OF DUST CONTINUUM IN 145 GALAXIES IN THE COSMOS SURVEY FIELD (2015, methodology): “The H2 column densities were taken from Pineda et al. (2010) who used NIR extinction measures as a primary measure of molecular gas column densities.”
ON THE STAR FORMATION EFFICIENCY OF TURBULENT MAGNETIZED CLOUDS (2012, background): “For instance, Taurus has a total molecular mass of about 1.5×104M (Pineda et al. 2010), and more than 300 YSOs were detected (see Table 1 in Kainulainen et al. 2009; Elias 1978).”
Molecular Clouds in the Milky Way (2015, methodology): “One can assume optically thin 13CO emission or derive the 13CO opacity, τ13(v), using the brightness of the optically thick 12CO line, if available, as a measure of the 13CO excitation temperature and then correct the optically thin column density value by the factor∫ τ13(v)dv/ ∫ [1 − exp[−τ13(v)]]d”
PHYSICAL PROPERTIES OF MOLECULAR CLOUDS FOR THE ENTIRE MILKY WAY DISK (2016, background): “This is comparable to the molecular mass of several clouds of the Gould Belt: Taurus (Pineda et al. 2010), Perseus (Lee et al. 2015), Ophiuchus (Loren 1989), and the Coalsack (Cambrésy 1999) all have masses in the range 1 − 3 × 104 M .”
THE STAR FORMATION RATE AND GAS SURFACE DENSITY RELATION IN THE MILKY WAY: IMPLICATIONS FOR EXTRAGALACTIC STUDIES (2010, methodology): “We include data points for the Taurus molecular cloud, including YSO counts from Rebull et al. (2010), Σgas from a 2MASS extinction map (Pineda et al. 2010), and the total 13CO and 12CO gas mass from Goldsmith et al. (2008).”
THE STAR FORMATION RATE OF TURBULENT MAGNETIZED CLOUDS: COMPARING THEORY, SIMULATIONS, AND OBSERVATIONS (2012, methodology): “The observational data are from Galactic observations of clouds and YSOs identified in the Spitzer Cores-to-Disks (C2D) and GB surveys (Evans et al. 2009) of massive dense clumps (Wu et al. 2010), and of the Taurus molecular cloud (Pineda et al. 2010; Rebull et al. 2010).”
A Herschel [C ii] Galactic plane survey - I. The global distribution of ISM gas components (2013, methodology): “Pineda et al. (2010a) used the RADEX (van der Tak et al. 2007) excitation/radiative transfer code to predict line intensities from a gas with conditions similar to those of mask CO1 in the envelope of the Taurus molecular cloud.”