Star formation in Chamaeleon I and III: a molecular line study of the starless core population

Abstract

The Chamaeleon clouds are excellent targets for low-mass star formation studies. Cha I and II are actively forming stars while Cha III shows no sign of ongoing star formation. We aim to determine the driving factors that have led to the very different levels of star formation activity in Cha I and III and examine the dynamical state and possible evolution of the starless cores within them. Observations were performed in various molecular transitions with APEX and Mopra. Five cores are gravitationally bound in Cha I and one in Cha III. The infall signature is seen toward 8-17 cores in Cha I and 2-5 cores in Cha III, which leads to a range of 13-28% of the cores in Cha I and 10-25% of the cores in Cha III that are contracting and may become prestellar. Future dynamical interactions between the cores will not be dynamically significant in either Cha I or III, but the subregion Cha I North may experience collisions between cores within ~0.7 Myr. Turbulence dissipation in the cores of both clouds is seen in the high-density tracers N2H+ 1-0 and HC3N 10-9. Evidence of depletion in the Cha I core interiors is seen in the abundance distributions of C17O, C18O, and C34S. Both contraction and static chemical models indicate that the HC3N to N2H+ abundance ratio is a good evolutionary indicator in the prestellar phase for both gravitationally bound and unbound cores. In the framework of these models, we find that the cores in Cha III and the southern part of Cha I are in a similar evolutionary stage and are less chemically evolved than the central region of Cha I. The measured HC3N/N2H+ abundance ratio and the evidence for contraction motions seen towards the Cha III starless cores suggest that Cha III is younger than Cha I Centre and that some of its cores may form stars in the future. The cores in Cha I South may on the other hand be transient structures. (abridged)

arXiv commentAccepted for publication in A&A. The resolution of Figure 2 has been degraded and the abstract in the metadata has been shortened to fit within the limits set by arXiv

References in corpus (49)

• Control of star formation by supersonic turbulence
• A computer program for fast non-LTE analysis of interstellar line spectra
• The Spitzer c2d Legacy Results: Star Formation Rates and Efficiencies; Evolution and Lifetimes
• From filamentary clouds to prestellar cores to the stellar IMF: Initial highlights from the Herschel Gould Belt survey
• The Stellar IMF from Turbulent Fragmentation
• The Formation of a Star Cluster: Predicting the Properties of Stars and Brown Dwarfs
• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• On the Formation of Massive Stars
• Star Formation in a Crossing Time
• The mass function of dense molecular cores and the origin of the IMF
• A three-phase chemical model of hot cores: the formation of glycine
• Massive star formation: Nurture, not nature
• A Search for Infall Motions Toward Nearby Young Stellar Objects
• The Mass Distribution and Lifetime of Prestellar Cores in Perseus, Serpens, and Ophiuchus
• The Stellar Population of the Chamaeleon I Star-Forming Region
• The Large APEX Bolometer Camera LABOCA
• A Catalogue of Optically Selected Cores
• Clouds as Turbulent Density Fluctuations. Implications for pressure confinement and spectral line data interpretation
• The initial conditions of isolated star formation - VI. SCUBA mapping of prestellar cores
• The initial conditions of star formation in the Ophiuchus main cloud: Kinematics of the protocluster condensations
• New Protostellar Collapse Candidates: An HCO+ Survey of the Class 0 Sources
• The Lifetimes and Evolution of Molecular Cloud Cores
• Molecular Excitation and Differential Gas-Phase Depletions in the IC 5146 Dark Cloud
• The Dynamical State of Barnard 68: A Thermally Supported, Pulsating Dark Cloud
• Quiescent Cores and the Efficiency of Turbulence-Accelerated, Magnetically Regulated Star Formation
• A Bubbling Nearby Molecular Cloud: COMPLETE Shells in Perseus
• The Mass Distributions of Starless and Protostellar Cores in Gould Belt Clouds
• Chemistry in Infrared Dark Clouds
• Enhancement of Ambipolar Diffusion Rates through Field Fluctuations
• The evolutionary state of the southern dense core Cha-MMS1
• Line Profiles of Cores within Clusters: I. The Anatomy of a Filament
• How to Identify Pre-Protostellar Cores
• On the Timescale for the Formation of Protostellar Cores in Magnetic Interstellar Clouds
• Dark cloud cores and gravitational decoupling from turbulent flows
• Herschel Observations of a Potential Core Forming Clump: Perseus B1-E
• Deuterium fractionation and the degree of ionisation in massive clumps within infrared dark clouds
• The Dynamical State of the Starless Dense Core FeSt 1-457: A Pulsating Globule?
• The Dynamical State fo the Starless Dense Core FeSt 1-457: A Pulsating Globule?
• Statistics of Core Lifetimes in Numerical Simulations of Turbulent, Magnetically Supercritical Molecular Clouds
• Clumpy filaments of the Chamaeleon I cloud: C18O mapping with the SEST
• The interstellar C18O/C17O ratio in the solar neighbourhood: The rho Oph cloud
• Oscillations in the stable starless core Barnard 68
• The dynamical state of the First Hydrostatic Core Candidate Cha-MMS1
• Multi-line spectral imaging of dense cores in the Lupus molecular cloud
• Will the starless cores in Chamaeleon I and III turn prestellar?
• A submillimetre survey of the kinematics of the Perseus molecular cloud - III. Clump kinematics
• Molecular Clouds as Ensembles of Transient Cores
• Dense and diffuse gas in dynamically active clouds
• A spectral line survey of the starless and proto-stellar cores detected by BLAST toward the Vela-D molecular cloud

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• The Gaia-ESO Survey: Structural and dynamical properties of the young cluster Chamaeleon I
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• The "C": The large Chameleon-Musca-Coalsack cloud
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