Astronomy and Astrophysics, volume 490, 1135-1142 (2008/11-2)
Chemical abundances of late-type pre-main sequence stars in the σ Orionis cluster.
GONZALEZ HERNANDEZ J.I., CABALLERO J.A., REBOLO R., BEJAR V.J.S., BARRADO Y NAVASCUES D., MARTIN E.L. and ZAPATERO OSORIO M.R.
Abstract (from CDS):
The young σ Orionis cluster is an important location for studying the formation and evolution of stars, brown dwarfs, and planetary-mass objects. Its metallicity, although it is a fundamental parameter, has not been well determined yet. We present the first determination of the metallicity of nine young late-type stars in σ Orionis. Using the optical and near-infrared broadband photometry available in the literature we derive the effective temperatures for these nine cluster stars, which lie in the interval 4300-6500K (1-3M☉). These parameters are employed to compute a grid of synthetic spectra based on the code MOOG and Kurucz model atmospheres. We employ a χ2-minimization procedure to derive the stellar surface gravity and atmospheric abundances of Al, Ca, Si, Fe, Ni and Li, using multi-object optical spectroscopy taken with WYFFOS+AF2 at the William Herschel Telescope (λ/δλ∼7500). The average metallicity of the σ Orionis cluster is [Fe/H] = -0.02±0.09±0.13 (random and systematic errors). The abundances of the other elements, except lithium, seem to be consistent with solar values. Lithium abundances are in agreement with the ``cosmic'' 7Li abundance, except for two stars which show a log ε(Li) in the range 3.6-3.7 (although almost consistent within the error bars). There are also other two stars with log ε(Li)∼2.75. We derived an average radial velocity of the σ Orionis cluster of 28±4km/s. The σ Orionis metallicity is roughly solar.
stars: abundances - stars: pre-main sequence - Galaxy: open clusters and associations: individual: σ Orionis
Table 1: [GCR2008] NNNNNN N=24 among (Nos 6-440660).
Table 2 [SWW2004] 125 is [SWW2004] J053751.521-023525.55 in Simbad.
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