A 2MASS Analysis of the Stability of Southern Bok Globules

Abstract

We used near-infrared 2MASS data to construct visual extinction maps of a sample of Southern Bok globules utilizing the NICE method. We derived radial extinction profiles of dense cores identified in the globules and analyzed their stability against gravitational collapse with isothermal Bonnor-Ebert spheres. The frequency distribution of the stability parameter xi_max of these cores shows that a large number of them are located in stable states, followed by an abrupt decrease of cores in unstable states. This decrease is steeper for globules with associated IRAS point sources than for starless globules. Moreover, globules in stable states have a Bonnor-Ebert temperature of T = 15 +- 6 K, while the group of critical plus unstable globules has a different temperature of T = 10 +- 3 K. Distances were estimated to all the globules studied in this work and the spectral class of the IRAS sources was calculated. No variations were found in the stability parameters of the cores and the spectral class of their associated IRAS sources. On the basis of 13CO J = 1-0 molecular line observations, we identified and modeled a blue-assymetric line profile toward a globule of the sample, obtaining an upper limit infall speed of 0.25 km/s.

arXiv comment53 pages, 15 figures, accepted for publication in ApJ

References in corpus (21)

• Dense Cores in Dark Clouds. XIV. N2H+(1-0) maps of dense cloud cores
• Physical Conditions in Regions of Star Formation
• Properties of the Youngest Protostars in Perseus, Serpens, and Ophiuchus
• Mapping the interstellar dust with near-infrared observations: An optimized multi-band technique
• A Survey for Infall Motions toward Starless Cores. II. $CS(2-1)$ and $N_2{H}^{+}(1-0)$ Mapping Observations
• Near Infrared Imaging Survey of Bok Globules: Density Structure
• Chemistry and Dynamics in Pre-Protostellar Cores
• Correlation Between Gas and Dust in Molecular Clouds: L977
• Structure of Protostellar Collapse Candidate B335 Derived from Near-Infrared Extinction Maps
• Molecular Line Profile Fitting with Analytic Radiative Transfer Models
• Deep Near-Infrared Observations of L1014: Revealing the nature of the core and its embedded source
• Centrally Condensed Collapse of Starless Cores
• From Dusty Filaments to Cores to Stars: An Infrared Extinction Study of Lupus 3
• A Pre-Protostellar Core in L1551
• Envelope Structure of Starless Core L694-2 Derived from a Near-Infrared Extinction Map
• A Near-Infrared Imaging Survey of Coalsack Globule 2
• The Physical and Chemical Status of Pre-protostellar Core B68
• The kinetic temperature of Barnard 68
• Discovery of a Dusty Ring in the Coalsack: A Dense Core Caught in the Act of Formation?
• A comparison of density structures of a star forming and a non-star-forming globule. DCld303.8-14.2 and Thumbprint Nebula
• A Pre-Protostellar Core in L1551. II. State of Dynamical and Chemical Evolution

Cited by in corpus (10)

• The Earliest Phases of Star formation observed with Herschel (EPoS): The dust temperature and density distributions of B68
• The Panchromatic Hubble Andromeda Treasury VIII: A Wide-Area, High-Resolution Map of Dust Extinction in M31
• Distances to dense cores that contain Very Low Luminosity Objects
• Two dimensional ice mapping of molecular cores
• Tracing the evolutionary stage of Bok globules: CCS and NH3
• Intensity-Corrected Herschel Observations of Nearby Isolated Low-Mass Clouds
• Searching for Galactic hidden gas through interstellar scintillation: Results from a test with the NTT-SOFI detector
• Dynamics of Molecular Clouds
• Magnetic field dispersion in the neighbourhood of Bok Globules
• A Survey of Magnetic Field Properties in Bok Globules