Study of Structure and Small-Scale Fragmentation in TMC-1

Langer, W. D.; Velusamy, T.; Kuiper, T. B. H.; Levin, S. M.; Olsen, E. H.; Migenes, V.

doi:10.1086/176389

Cited by 92 publications

(88 citation statements)

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“…Molecular clouds exhibit supersonic line widths, which are interpreted as supersonic turbulence (Zuckerman & Evans 1974). Such supersonic turbulence seems to be common in the wide range from molecular clouds to molecular cloud cores (Langer et al 1995).…”

Section: Introductionmentioning

confidence: 99%

Protostellar Collapse of Magneto-Turbulent Cloud Cores: Shape During Collapse and Outflow Formation

Matsumoto

Hanawa

2011

ApJ

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We investigate the protostellar collapse of molecular cloud cores using numerical simulations, taking into account turbulence and magnetic fields. By using the adaptive mesh refinement technique, the collapse is followed over a wide dynamic range from the scale of a turbulent cloud core to that of the first core. The cloud core is lumpy in the low density region owing to the turbulence, while it has a smooth density distribution in the dense region produced by the collapse. The shape of the dense region depends mainly on the mass of the cloud core; a massive cloud core tends to be prolate while a less massive cloud core tends to be oblate. In both cases, the anisotropy of the dense region increases during the isothermal collapse (n 10 11 cm −3 ). The minor axis of the dense region is always oriented parallel to the local magnetic field. All the models eventually yield spherical first cores (n 10 13 cm −3 ) supported mainly by the thermal pressure. Most of turbulent cloud cores exhibit protostellar outflows around the first cores. These outflows are classified into two types, bipolar and spiral flows, according to the morphology of the associated magnetic field. Bipolar flow often appears in the less massive cloud core. The rotation axis of the first core is oriented parallel to the local magnetic field for bipolar flow, while the orientation of the rotation axis from the global magnetic field depends on the magnetic field strength. In spiral flow, the rotation axis is not aligned with the local magnetic field.

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Section: Introductionmentioning

confidence: 99%

Protostellar Collapse of Magneto-Turbulent Cloud Cores: Shape During Collapse and Outflow Formation

Matsumoto

Hanawa

2011

ApJ

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“…The global velocity gradient is less important than the local velocity gradient. In this sense, small-scale inhomogeneity in the cloud core (see, e.g., Langer et al 1995) may be responsible for bar formation and accordingly for binary formation.…”

Section: Application To Formation Of Binary and Multiple Starsmentioning

confidence: 99%

Bar and Disk Formation in Gravitationally Collapsing Clouds: Implications for Binary Formation

Matsumoto

Hanawa

1999

ApJ

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We investigated the dynamical collapse of a molecular cloud core with three-dimensional numerical simulations. Our simulations show that an initially spherical core produces a bar or disk during its dynamical collapse. The disk and bar formation is due to instability. Velocity perturbations grow in proportion to where denotes the central density. The growing velocity perturbations are due to two o c 1@6, o c e †ects, rotation and shear. Rotation makes the core spin faster to produce a disk at the center. On the other hand, velocity shear elongates or shortens the core in one direction to form a bar or nonrotating disk. When the core rotates nonuniformly, the collapse produces a disk containing a bar at its center by the growth of rotation and shear. This bar is much longer than the Jeans length and is likely to be unstable against fragmentation. We expect that the bar will evolve into a binary or multiple stars. The binary or multiple stars will be surrounded by a common disk. We also demonstrate the growth of an eigenmode that leads to bar and disk formation. On the basis of our numerical simulations, we give a condition for formation of a disk and bar during the isothermal collapse phase of a molecular cloud core. If the core has an oblateness of 10% or an equivalent velocity shear at cm~3, the core n H2^1 04 produces a bar by the end of its isothermal collapse phase.

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“…wellseparated cyanopolyyne, ammonia (Little et al 1979), and SO (Pratap et al 1997) peaks (see also Table 1). Studies of NH 3 , HC n N (n = 3, 5, 7), C 4 H, CS, C 34 S, HCS + (Tölle et al 1981;Gaida et al 1984;Olano et al 1988;Hirahara et al 1992), CH (Suutarinen et al 2011;Sakai et al 2012), and other carbonchain and sulfur-containing molecules (Langer et al 1995;Pratap et al 1997) show complex velocity and chemical structure in TMC-1. Hirahara et al (1992) suggested that the displacement of the column density peaks of carbon-chain and nitrogen bearing molecules is due to different evolutionary states of the regions.…”

Section: Introductionmentioning

confidence: 99%

“…Cernicharo & Guelin (1987) considered TMC-1 a clump inside a thick, bent filamentary complex projecting itself as a loop on the plane of the sky. The existence and relative motion of fragments in TMC-1 were discussed in various papers (Snell et al 1982;Schloerb et al 1983;Olano et al 1988;Hirahara et al 1992;Langer et al 1995;Pratap et al 1997). Nutter et al (2008) concluded that in sub-millimeter and FIR, TMR is composed of a dense filament on one side (TMC-1) and a series of point-like sources on the other.…”

Section: Introductionmentioning

confidence: 99%

Structure and stability in TMC-1: Analysis of NH₃molecular line andHerschelcontinuum data

Fehér

Tóth

Ward-Thompson

et al. 2016

A&A

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Aims. We examined the velocity, density, and temperature structure of Taurus molecular cloud-1 (TMC-1), a filamentary cloud in a nearby quiescent star forming area, to understand its morphology and evolution. Methods. We observed high signal-to-noise (S/N), high velocity resolution NH 3 (1,1), and (2, 2) emission on an extended map. By fitting multiple hyperfine-split line profiles to the NH 3 (1, 1) spectra, we derived the velocity distribution of the line components and calculated gas parameters on several positions. Herschel SPIRE far-infrared continuum observations were reduced and used to calculate the physical parameters of the Planck Galactic Cold Clumps (PGCCs) in the region, including the two in TMC-1. The morphology of TMC-1 was investigated with several types of clustering methods in the parameter space consisting of position, velocity, and column density. Results. Our Herschel-based column density map shows a main ridge with two local maxima and a separated peak to the south-west. The H 2 column densities and dust colour temperatures are in the range of 0.5−3.3 × 10 22 cm −2 and 10.5−12 K, respectively. The NH 3 column densities and H 2 volume densities are in the range of 2.8−14.2 × 10 14 cm −2 and 0.4−2.8 × 10 4 cm −3 . Kinetic temperatures are typically very low with a minimum of 9 K at the maximum NH 3 and H 2 column density region. The kinetic temperature maximum was found at the protostar IRAS 04381+2540 with a value of 13.7 K. The kinetic temperatures vary similarly to the colour temperatures in spite of the fact that densities are lower than the critical density for coupling between the gas and dust phase. The k-means clustering method separated four sub-filaments in TMC-1 with masses of 32.5, 19.6, 28.9, and 45.9 M and low turbulent velocity dispersion in the range of 0.13−0.2 km s −1 . Conclusions. The main ridge of TMC-1 is composed of four sub-filaments that are close to gravitational equilibrium. We label these TMC-1F1 through F4. The sub-filaments TMC-1F1, TMC-1F2, and TMC-1F4 are very elongated, dense, and cold. TMC-1F3 is a little less elongated and somewhat warmer, and probably heated by the Class I protostar, IRAS 04381+2540, which is embedded in it. TMC-1F3 is approximately 0.1 pc behind TMC1-F1. Because of its structure, TMC-1 is a good target to test filament evolution scenarios.

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Study of Structure and Small-Scale Fragmentation in TMC-1

Cited by 92 publications

References 0 publications

Protostellar Collapse of Magneto-Turbulent Cloud Cores: Shape During Collapse and Outflow Formation

Protostellar Collapse of Magneto-Turbulent Cloud Cores: Shape During Collapse and Outflow Formation

Bar and Disk Formation in Gravitationally Collapsing Clouds: Implications for Binary Formation

Structure and stability in TMC-1: Analysis of NH₃molecular line andHerschelcontinuum data

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Study of Structure and Small-Scale Fragmentation in TMC-1

Cited by 92 publications

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Protostellar Collapse of Magneto-Turbulent Cloud Cores: Shape During Collapse and Outflow Formation

Protostellar Collapse of Magneto-Turbulent Cloud Cores: Shape During Collapse and Outflow Formation

Bar and Disk Formation in Gravitationally Collapsing Clouds: Implications for Binary Formation

Structure and stability in TMC-1: Analysis of NH3molecular line andHerschelcontinuum data

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Structure and stability in TMC-1: Analysis of NH₃molecular line andHerschelcontinuum data