Young starless cores embedded in the magnetically dominated Pipe Nebula. II. Extended dataset

Abstract

The Pipe nebula is a massive, nearby, filamentary dark molecular cloud with a low star-formation efficiency threaded by a uniform magnetic field perpendicular to its main axis. It harbors more than a hundred, mostly quiescent, very chemically young starless cores. The cloud is, therefore, a good laboratory to study the earliest stages of the star-formation process. We aim to investigate the primordial conditions and the relation among physical, chemical, and magnetic properties in the evolution of low-mass starless cores. We used the IRAM 30-m telescope to map the 1.2 mm dust continuum emission of five new starless cores, which are in good agreement with previous visual extinction maps. For the sample of nine cores, which includes the four cores studied in a previous work, we derived a Av to NH2 factor of (1.27$\pm$0.12)$\times 10^{-21}$ mag cm${}^2$ and a background visual extinction of ~6.7 mag possibly arising from the cloud material. We derived an average core diameter of ~0.08 pc, density of ~10${}^5$ cm${}^{-3}$, and mass of ~1.7 Msun. Several trends seem to exist related to increasing core density: (i) diameter seems to shrink, (ii) mass seems to increase, and (iii) chemistry tends to be richer. No correlation is found between the direction of the surrounding diffuse medium magnetic field and the projected orientation of the cores, suggesting that large scale magnetic fields seem to play a secondary role in shaping the cores. The full abstract is available in the pdf.

19 pages, 12 figures, 13 tables, accepted for publication in ApJ

References in corpus (10)

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Cited by in corpus (12)

• On the radiation driven alignment of dust grains: Detection of the polarization hole in a starless core
• Evolution and excitation conditions of outflows in high-mass star-forming regions
• Molecular outflow launched beyond the disk edge
• The mid-infrared extinction law in the darkest cores of the Pipe Nebula
• Formation of dense structures induced by filament collisions. Correlation of density, kinematics and magnetic field in the Pipe nebula
• Some like it cold: molecular emission and effective dust temperatures of dense cores in the Pipe Nebula
• Simultaneous evolution of the virial parameter and star formation rate in molecular clumps undergoing global hierarchical collapse
• An efficient method for determining the chemical evolution of gravitationally collapsing prestellar cores
• The impact of magnetic fields on the chemical evolution of the supernova-driven ISM
• Ambipolar diffusion and the molecular abundances in prestellar cores
• A correlation between chemistry, polarization and dust properties in the Pipe Nebula starless core FeSt 1-457
• Collapse and Fragmentation of Magnetic Molecular Cloud Cores with the Enzo AMR MHD Code. II. Prolate and Oblate Cores