The lithium depletion boundary in NGC 2547 as a test of pre-main-sequence evolutionary models |
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| Authors: | R D Jeffries J M Oliveira |
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| Institution: | Astrophysics Group, School of Chemistry and Physics, Keele University, Keele, Staffordshire ST5 5BG |
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| Abstract: | Intermediate resolution spectroscopy from the European Southern Observatory Very Large Telescope is analysed for 63 photometrically selected low-mass (0.08–0.30 M⊙) candidates of the open cluster NGC 2547. We have confirmed membership for most of these stars using radial velocities, and found that lithium remains undepleted for cluster stars with I > 17.54 ± 0.14 and Ks > 14.86 ± 0.12 . From these results, several pre–main-sequence evolutionary models give almost model independent ages of 34–36 Myr, with a precision of 10 per cent. These ages are only slightly larger than the ages of 25–35(±5) Myr obtained using the same models to fit isochrones to higher mass stars descending towards the zero-age main-sequence, both in empirically calibrated and theoretical colour–magnitude diagrams. This agreement between age determinations in different mass ranges is an excellent test of the current generation of low-mass pre–main-sequence stellar models and lends confidence to ages determined with either method between 30 and 120 Myr. |
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| Keywords: | stars: abundances stars: late-type open clusters and associations: individual: NGC 2547 |
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