Abstract
ABSTRACT Spectroscopic observations of three of the relatively old (220 million years) pre-main-sequence stars of the Pleiades cluster are presented. The observations were carried out at a dispersion of 30 A/mm in the blue and 60 A/mm in the red spectral ranges and resolutions of 1.7 and 3.5 A, respectively, with the image dissector scanner at the ESO 3.6-m telescope. All three stars are observed to show H-alpha, H-gamma and Ca II H and K emission, with H-delta emission also observed in H-134 and H-1321 and H-epsilon possibly present in H-1173. Broad emission lines are noted for H-134, with widths (FWHM approximately 110 km/sec) considerably greater than those of older field dMe stars (FWHM approximately 20 km/sec). The emission-line broadening, which may be a relic of the T Tauri phase, is explained by direct production in the line-emitting region. A search for the Li 6707 resonance line reveals an upper limit of 0.6 for the log of Li abundance on the observed stars, consistent with extrapolation results of Zappala (1972) on stars of late spectral type.
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