Optical spectra of selected Chamaeleon I young stellar objects^*

¹ Observatorio Astronómico de Córdoba, Laprida 854, 5000 Córdoba, Argentina e-mail: saffe@oac.uncor.edu;mercedes@oac.uncor.edu;german@oac.uncor.edu
² INAF–Osservatorio Astrofisico di Arcetri, L.go E. Fermi, 5 50125 Firenze, Italia e-mail: randich@arcetri.astro.it;caselli@arcetri.astro.it
³ Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile e-mail: mardones@das.uchile.cl
⁴ Istituto Astrofisica Spaziale e Fisica Cosmica, CNR, Via del Fosso del Cavaliere 00133, Roma, Italia e-mail: persi@rm.iasf.cnr.it

Corresponding author: C. Saffe, saffe@oac.uncor.edu

Received: 25 April 2003
Accepted: 22 July 2003

Abstract

We present optical spectra of eight candidate brown dwarfs and a previously known T Tauri star (Sz 33) of the Chamaeleon I dark cloud. We derived spectral types based on the strength of the TiO or VO absorption bands present in the spectra of these objects as well as on the PC3 index of Martin et al. (1999). Photometric data from the literature are used to estimate the bolometric luminosities for these sources. We apply D'Antona & Mazzitelli(1997) pre-main sequence evolutionary tracks and isochrones to derive masses and ages. Based on the presence of Hα in emission, we confirm that most of the candidates are young objects. Our sample however includes two sources for which we can only provide upper limits for the emission in Hα; whereas these two objects are most likely foreground/background stars, higher resolution spectra are required to confirm their true nature. Among the likely cloud members, we detect one new sub-stellar object and three transition stellar/sub-stellar sources.