The young population of the Chamaeleon II dark cloud

Abstract

We discuss the results of the optical spectroscopic follow-up of pre-main sequence (PMS) objects and candidates selected in the Chamaeleon II dark cloud based on data from the Spitzer Legacy survey "From Molecular Cores to Planet Forming Disks" (c2d) and from previous surveys. Our sample includes both objects with infrared excess selected according to c2d criteria and referred to as Young Stellar Objects and other cloud members and candidates selected from complementary optical and near-infrared data. We characterize the sample of objects by deriving their physical parameters. The vast majority of objects have masses < 1 solar mass and ages < 6 Myr. Several of the PMS objects and candidates lie very close to or below the Hydrogen-burning limit. A first estimate of the slope of the Initial Mass Function in Cha II is consistent with that of other T associations. The star formation efficiency in the cloud (1-4%) is consistent with our own estimates for Taurus and Lupus, but significantly lower than for Cha I. This might mean that different star-formation activities in the Chamaeleon clouds may reflect a different history of star formation. We also find that the Cha II cloud is turning some 8 solar masses into stars every Myr, which is less than the star formation rate in the other c2d clouds. However, the star formation rate is not steady and evidence is found that the star formation in Cha II might have occurred very rapidly. The H_alpha emission of the Cha II PMS objects, as well as possible correlations between their stellar and disk properties, are also investigated.

51 pages, 14 figures

References in corpus (7)

• A Submillimeter View of Circumstellar Dust Disks in $\rho$ Ophiuchus
• Low-Mass Dwarf Template Spectra from the Sloan Digital Sky Survey
• Characterizing Young Brown Dwarfs using Low Resolution Near-IR Spectra
• Young, Low-Mass Brown Dwarfs with Mid-Infrared Excesses
• The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds.X. The Chamaeleon II Pre-Main Sequence Population as Observed With IRAC and MIPS
• Spectroscopy of Young Planetary Mass Candidates with Disks
• A WFI survey in the Chamaeleon II dark cloud

Cited by in corpus (18)

• The Mass Distribution and Lifetime of Prestellar Cores in Perseus, Serpens, and Ophiuchus
• Herschel's view of the large-scale structure in the Chamaeleon dark clouds
• Low EUV Luminosities Impinging on Protoplanetary Disks
• Dust properties inside molecular clouds from coreshine modeling and observations
• Chamaeleon DANCe. Revisiting the stellar populations of Chamaeleon I and Chamaeleon II with Gaia-DR2 data
• POISSON project - III - Investigating the evolution of the mass accretion rate
• The mass and size of Herbig disks as seen by ALMA
• The Gaia-ESO Survey: metallicity of the Chamaeleon I star forming region
• Large gaps and high accretion rates in photoevaporative transition disks with a dead zone
• Proper motions of young stars in Chamaeleon. I. A Virtual Observatory study of spectroscopically confirmed members
• Herschel-PACS observations of far-IR lines in YSOs I: [OI] and H2O at 63 microns
• Determining Dust Properties in Protoplanetary Disks: SED-derived Masses and Settling With ALMA
• Probing protoplanetary disk evolution in the Chamaeleon II region
• Crescent-Shaped Molecular Outflow from the Intermediate-mass Protostar DK Cha Revealed by ALMA
• An SMA Survey of Chemistry in Disks around Herbig AeBe Stars
• Herschel -PACS observations of [OI] and H2O in Cha II
• Disk dissipation, giant planet formation and star-formation-rate fluctuations in the past three-million-year history of Gould's Belt
• A framework for modeling the evolution of young stellar objects