Large-Scale Structure of the Molecular Gas in Taurus Revealed by High Linear Dynamic Range Spectral Line Mapping

By Paul F. Goldsmith, M. Heyer, G. Narayanan, R. Snell, Di Li, C. Brunt. 2008

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We report the results of a 100 deg2 survey of the Taurus molecular cloud region in 12CO and 13CO J = 1→ 0. The image of the cloud in each velocity channel includes ≃3 × 106 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 12CO 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 12CO but not 13CO 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 × 104 M☉, more than twice as large as would be obtained using a canonical fixed fractional abundance of 13CO, 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 × 1021 cm−2. The distribution of young stars in the region covered is highly nonuniform, with the probability of finding a star in a pixel with a specified column density rising sharply for N(H2) = 6 × 1021 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.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/899112ff60809cdb3020ac99d8619e52471c326b

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Citations in the corpus

The Formation and Destruction of Molecular Clouds and Galactic Star Formation (2015, background): “We can also see many faint filamentary structuresthat mimic “striations” observed in the Taurus Dark Cloud and arealmost parallel to the mean magnetic field lines (Goldsmith et al. 2008).”
Magnetically Regulated Star Formation in Three Dimensions: The Case of the Taurus Molecular Cloud Complex (2008, methodology): “…comes from the fact that star formation is slow even in dense gas: the rate of star formation for the last 3 million years is about Ṁ∗ ∼ 5 × 10−5 M⊙yr−1 (Goldsmith et al. 2008), two orders of magnitude below the free-fall rate for the dense (∼ 104 cm−3) C18O gas (Onishi et al. 2002; see §…”
PHYSICAL PROPERTIES AND GALACTIC DISTRIBUTION OF MOLECULAR CLOUDS IDENTIFIED IN THE GALACTIC RING SURVEY (2010, background): “Wolfire et al. (2010) predicts that 30% of a molecular cloud’s mass is in the form of CO-dark molecular envelope, while Goldsmith et al. (2008) predicts 50%.”
THE STAR FORMATION RATE AND GAS SURFACE DENSITY RELATION IN THE MILKY WAY: IMPLICATIONS FOR EXTRAGALACTIC STUDIES (2010, methodology): “A few clouds have been mapped to still lower levels and a factor of two more mass is found in Taurus, for example Goldsmith et al. (2008).”
THE RELATION BETWEEN GAS AND DUST IN THE TAURUS MOLECULAR CLOUD (2010, methodology): “THE N(H2) MAP DERIVED FROM 12CO AND 13CO In the following we derive the column density of CO using the FCRAO 14–m 12CO and 13CO observations presented by Narayanan et al. 2008 (see also Goldsmith et al. 2008).”
The importance of radiative feedback for the stellar initial mass function (2008, background): “The Taurus-Auriga star-forming region is a large but diffuse molecular cloud spanning 30 pc and containing 2 × 104 M of molecular gas (Goldsmith et al. 2008).”
FILAMENTARY STRUCTURE OF STAR-FORMING COMPLEXES (2009, background): “…1962, Feitzinger & Stüwe 1984, Schneider & Elmegreen 1979, Dobashi et al 2005), infrared (Lada, Alves & Lombardi 2007), and submillimeter wavelengths (Motte, André & Neri 1998), and in rotational lines of CO and its isotopes (Ungerechts & Thaddeus 1987, Mizuno et al 1995, Goldsmith et al 2008).”
RE-EXAMINING LARSON'S SCALING RELATIONSHIPS IN GALACTIC MOLECULAR CLOUDS (2008, background): “However, the mass discrepancy illustrated in Figure 3 is larger than differences measured for clouds in the Solar neighborhood (Heyer et al. 2006; Goldsmith et al. 2008).”
Star Formation in the Milky Way and Nearby Galaxies (2012, background): “CO does emit beyond the area where 13CO is detectable and even, at a low level, beyond the usual detection threshold for CO. Stacking analysis of positions beyond the usual boundary of the Taurus cloud suggest a factor of two additional mass in this transition region (Goldsmith et al. 2008).”
MAPPING THE SHORES OF THE BROWN DWARF DESERT. II. MULTIPLE STAR FORMATION IN TAURUS–AURIGA (2011, background): “Stars seem to form along large-scale filaments in their progenitor giant molecular cloud (Goldsmith et al. 2008; Menshchikov et al. 2010), so if protostellar cores remain elongated as they collapse (as might be suggested by observations; Tobin et al. 2010), then wide companions could form more…”
PHYSICAL PROPERTIES OF MOLECULAR CLOUDS FOR THE ENTIRE MILKY WAY DISK (2016, background): “When observed at higher angular resolution, these large puffy clouds appear fragmented with abundant small-scale structures (Jackson et al. 2006; Goldsmith et al. 2008).”
THE TAURUS SPITZER SURVEY: NEW CANDIDATE TAURUS MEMBERS SELECTED USING SENSITIVE MID-INFRARED PHOTOMETRY (2009, background): “Finally, the Five College Radio Astronomy Observatory (FCRAO) millimeter wavelength survey (Goldsmith et al. 2008) mapped ∼100 square degrees in the CO(1-0) line, covering the Spitzer survey area entirely.”
Molecular Clouds in the Milky Way (2015, methodology): “Adapted from figure 12 of Goldsmith et al. (2008) and reproduced with permission from AAS.”
STAR FORMATION RATES IN MOLECULAR CLOUDS AND THE NATURE OF THE EXTRAGALACTIC SCALING RELATIONS (2011, result): “Similar surface density thresholds for star formation in local clouds have been suggested in other recent studies (e.g., Goldsmith et al 2008; Heiderman et al. 2010).”
Planck 2018 results (2018, methodology): “…SRoll destriper capabilities, we attempted at 100 GHz to extract the response differences to the two isotopologue (i.e., 12CO and 13CO) lines within its global minimization, using as templates millimetre spectroscopy maps of 64 deg2 in the Taurus region for these two lines (Goldsmith et al. 2008).”
Cores, filaments, and bundles: hierarchical core formation in the L1495/B213 Taurus region (2013, background): “Such chemical youth is again in good agreement with the lack of stellar population, which has already been used to argue that the B211 region is at a very early state of evolution (Goldsmith et al. 2008; Schmalzl et al. 2010).”