The lithium depletion boundary in NGC 2547 as a test of pre-main-sequence evolutionary models

• Published in: Monthly notices of the Royal Astronomical Society Vol. 358; no. 1; pp. 13 - 29
• Main Authors: Jeffries, R. D., Oliveira, J. M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.03.2005; Blackwell Science Ltd; Blackwell Science
• Subjects: open clusters and associations: individual: NGC 2547; stars: abundances; stars: late-type; open clusters and associations: individual: NGC 2547; Spectroscopy; Late type stars; Isochrone; Stellar abundance; Open clusters; Star clusters; Star models; stars: abundances; Stellar mass; stars: late-type; Color-magnitude diagrams; Radial velocity; Age
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2005.08820.x

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.