2008/08/23 by K. L. Luhman, Luhman, Kevin L.
Arts and Humanities · #Astrophysics (astro-ph) #FOS: Physical sciences #Historical Art and Culture Studies
paper · pdf · doi:10.48550/arxiv.0808.3207
openalex publication_date 2008/08/23 · openalex created_date 2024/04/11 · openalex updated_date 2026/07/28
The dark clouds in the constellation of Chamaeleon have distances of 160-180 pc from the Sun and a total mass of ~5000 Msun. The three main clouds, Cha I, II, and III, have angular sizes of a few square degrees and maximum extinctions of AV=5-10. Most of the star formation in these clouds is occurring in Cha I, with the remainder in Cha II. The current census of Cha I contains 237 known members, 33 of which have spectral types indicative of brown dwarfs (>M6). Approximately 50 members of Cha II have been identified, including a few brown dwarfs. When interpreted with the evolutionary models of Chabrier and Baraffe, the H-R diagram for Cha I exhibits a median age of ~2 Myr, making it coeval with IC 348 and slightly older than Taurus (~1 Myr). The IMF of Cha I reaches a maximum at a mass of 0.1-0.15 Msun, and thus closely resembles the IMFs in IC 348 and the Orion Nebula Cluster. The disk fraction in Cha I is roughly constant at ~50% from 0.01 to 0.3 Msun and increases to ~65% at higher masses. In comparison, IC 348 has a similar disk fraction at low masses but a much lower disk fraction at M>1 Msun, indicating that solar-type stars have longer disk lifetimes in Cha I.