Cores, filaments, and bundles: hierarchical core formation in the L1495/B213 Taurus region

By Á. Hacar, M. Tafalla, J. Kauffmann, A. Kovács. 2013

284 citations recorded by the source corpus.

Context. Core condensation is a critical step in the star-formation process, but it is still poorly characterized observationally. Aims. We have studied the 10 pc-long L1495/B213 complex in Taurus to investigate how dense cores have condensed out of the lower density cloud material. Methods. We observed L1495/B213 in C 18 O(1−0), N 2 H + (1−0), and SO( J N  = 3 2 –2 1 ) with the 14 m FCRAO telescope, and complemented the data with dust continuum observations using APEX (870 μ m) and IRAM 30 m (1200 μ m). Results. From the N 2 H + emission, we identify 19 dense cores, some starless and some protostellar. They are not distributed uniformly, but tend to cluster with relative separations on the order of 0.25 pc. From the C 18 O emission, we identify multiple velocity components in the gas. We have characterized them by fitting Gaussians to the spectra and by studying the distribution of the fits in position–position–velocity space. In this space, the C 18 O components appear as velocity-coherent structures, and we identify them automatically using a dedicated algorithm (FIVE: Friends In VElocity). Using this algorithm, we identify 35 filamentary components with typical lengths of 0.5 pc, sonic internal velocity dispersions, and mass-per-unit length close to the stability threshold of isothermal cylinders at 10 K. Core formation seems to have occurred inside the filamentary components via fragmentation, with few fertile components with higher mass-per-unit length being responsible for most cores in the cloud. On large scales, the filamentary components appear grouped into families, which we refer to as bundles. Conclusions. Core formation in L1495/B213 has proceeded by hierarchical fragmentation. The cloud fragmented first into several pc-scale regions. Each of these regions later fragmented into velocity-coherent filaments of about 0.5 pc in length. Finally, a small number of these filaments fragmented quasi-statically and produced the individual dense cores we see today.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/ed620dfa2311199e6374f0bb65c278a385287392

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In Astronomy and Astrophysics

1. Á. Hacar
2. S. Oh
3. Ryan M. O’Leary
4. A. Madigan
5. Christoph Federrath
6. J. Forbrich
7. P. Teixeira
8. João Alves

In Spectroscopy

1. Á. Hacar
2. M. Tafalla
3. Christoph Federrath
4. J. Forbrich

Citations in the corpus

• An ALMA study of the Orion Integral Filament: I. Evidence for narrow fibers in a massive cloud (2018, methodology): “In both Taurus and Orion, the observed fibers closely follow these predictions showing roughly similar λ f rag FWHM ∼ 3 (see similar results in Schneider & Elmegreen 1979).”
• On the universality of interstellar filaments: theory meets simulations and observations (2015, background): “E-mail: christoph.federrath@anu.edu.au et al. 2015; Kainulainen et al. 2015), coherent velocity structures (Hacar et al. 2013; Moeckel & Burkert 2015; Smith et al. 2016) and orientations preferentially (but not always) perpendicular to the magnetic field direction (Sugitani et al. 2011; Gaensler et…”
• A characteristic scale for cold gas (2016, result): “In similar observations, but at lower temperature, Hacar & Tafalla (2011) and Hacar et al. (2013) demonstrate in a careful analysis that molecular filaments in the interstellar medium with strongly suprathermal line widths resolve into ∼ 10s of smaller sub-filaments, each with approximately thermal…”