The Spitzer c2d survey of large, nearby, interstellar clouds. X. the chamaeleon II pre-main-sequence population as observed with IRAC and MIPS

Research output: Contribution to journalJournal articlepeer-review

  • Juan M. Alcalá
  • Loredana Spezzi
  • Nicholas Chapman
  • Neal J. Evans
  • Tracy L. Huard
  • Jørgensen, Jes Kristian
  • Bruno Merín
  • Karl R. Stapelfeldt
  • Elvira Covino
  • Antonio Frasca
  • Davide Gandolfi
  • Isa Oliveira

We discuss the results from the combined IRAC and MIPS c2d Spitzer Legacy survey observations and complementary optical and NIR data of the Chamaeleon II (Cha II) dark cloud. We perform a census of the young population in an area of ∼ 1.75 deg2 and study the spatial distribution and properties of the cloud members and candidate premain-sequence (PMS) objects and their circumstellar matter. Our census is complete down to the substellar regime (M ≈ 0.03 M). From the analysis of the volume density of the PMS objects and candidates we find two groups of objects with volume densities higher than 25 M pc-3 and 5-10 members each. A multiplicity fraction of about 13% ± 3% is observed for objects with separations 0.8″ < θ < 6.0″ (142-1065 AU). No evidence for variability between the two epochs of the c2d IRAC data set, Δt ∼ 6 hr, is detected. We estimate a star formation efficiency of 1%-4%, consistent with the estimates for Taurus and Lupus, but lower than for Cha I. This mightmean that different star formation activities in the Chamaeleon clouds reflect a different history of star formation. We also find that Cha II is turning some 6-7 M⊙ into stars every Myr, which is low in comparison with the star formation rate in other c2d clouds. The disk fraction of 70%-80% that we estimate in Cha II is much higher than in other star-forming regions and indicates that the population in this cloud is dominated by objects with active accretion. Finally, the Cha II outflows are discussed; a new Herbig-Haro outflow, HH 939, driven by the classical T Tauri star Sz 50, has been discovered.

Original languageEnglish
JournalAstrophysical Journal
Volume676
Issue number1
Pages (from-to)427-463
Number of pages37
ISSN0004-637X
DOIs
Publication statusPublished - 20 Mar 2008
Externally publishedYes

    Research areas

  • Circumstellar matter, Infrared: stars, Planetary systems: protoplanetary disks, Stars: formation, Stars: low-mass, brown dwarfs, Stars: pre-main-sequence

ID: 234017315