Near-IR Spectra of ISO Detected Chamaeleon I Young Stellar Objects

M. GÓMEZ, P. PERSI, G. OLOFSSON

Córdoba

Congreso; X Reunion Regional Latinoamericana de Astronomia; 2001

IAU

We present 0.95 -- 2.5 micron moderate (R about 500) resolution spectra of 19 ISOCAM detected sources in the Chamaeleon I dark cloud. Thirteen of these sources are candidate very low mass members of the cloud proposed by Persi et al. (2000, A&A 357, 219) based on their mid-IR color excesses. Three show no mid-IR excesses and the other three (Sz 33, Cha Halpha 1, and Cha Hapha 2) are previously known members of the cloud. The spectra of previously known and ISO detected mid-IR excess sources are relatively flat andfeatureless in this wavelength range. Both atomic and molecular lines (when in absorption) are veiled suggesting the presence of continuum emission from circumstellar dust. In addition some of the sources show emission lines. The overall shape of the spectra in this wavelength range as well as the presence of veiled absorption and emission lines indicate that these sources are potential Class II young stellar members of the Chamaeleon I dark cloud. We apply the 2 micro water vapor index defined by Wilking et al. (1999, AJ 117, 469) to estimate spectral type for these sources. Most of the stars have spectral types M2-8. Finally we use Persi et al.'s luminosity determinations, in combination with D?Antona & Mazzitelli latest pre-main sequence evolutionary tracks, to estimate masses and ages for these stars. These sources have masses between 0.4 M_Sun and 0.08 M_Sun and ages of about 3 x 10^6 yrs, in good agreement with the higher mass members of this cloud.