Astronomy & Astrophysics

Free access article

Issue		A&A Volume 409, Number 3, October III 2003
Page(s)		993 - 1005
Section		Stellar atmospheres
DOI		10.1051/0004-6361:20031150

A&A 409, 993-1005 (2003)
DOI: 10.1051/0004-6361:20031150

Optical spectra of selected Chamaeleon I young stellar objects

C. Saffe¹, M. Gómez¹, S. Randich², D. Mardones³, P. Caselli², P. Persi⁴ and G. Racca¹

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

(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 H $\alpha$ 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 H $\alpha$ ; 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.

Key words: stars: pre-main sequence -- stars: Hertzsprung-Russell (HR) diagram -- stars: low-mass, brown dwarfs -- infrared: stars

Offprint request: C. Saffe, saffe@oac.uncor.edu

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