Oliveira, JM and Jeffries, RD and Devey, CR and Navascues, DBY and Naylor, T and Stauffer, JR and Totten, EJ (2003) The lithium depletion boundary and the age of NGC 2547. Monthly Notices of the Royal Astronomical Society, 342. 651 - ?. ISSN 1365-2966
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We present the results of a photometric and spectroscopic survey of cool M dwarf candidates in the young open cluster NGC 2547. Using the 2dF fiber spectrograph, we have searched for the luminosity at which lithium remains unburned in an attempt to constrain the cluster age. The lack of a population of individual lithium-rich objects towards the faint end of our sample places a very strong lower limit to the cluster age of 35 Myr. However, the detection of lithium in the averaged spectra of our faintest targets suggests that the lithium depletion boundary lies at 9.5 < M(I) < 10.0 and that the cluster age is < 54 Myr. The age of NGC 2547 judged from fitting isochrones to low-mass pre-main-sequence stars in colour-magnitude diagrams is 20-35 Myr using the same evolutionary models. The sense and size of the discrepancy in age determined by these two techniques is similar to that found in another young cluster, IC 2391, and in the low-mass pre main-sequence binary system, GJ 871.1AB. We suggest that the inclusion of rotation or dynamo-generated magnetic fields in the evolutionary models could reconcile the two age determinations, but only at the expense of increasing the cluster ages beyond that currently indicated by the lithium depletion. Alternatively, some mechanism is required that increases the rate of lithium depletion in young, very low-mass fully convective stars.
|Uncontrolled Keywords:||stars, abundances, late-type, stars, interiors, open clusters and associations, NGC 2547|
|Subjects:||Q Science > QB Astronomy
Q Science > QC Physics
|Divisions:||Faculty of Natural Sciences > School of Physical and Geographical Sciences|
|Date Deposited:||19 May 2015 09:44|
|Last Modified:||05 May 2016 08:36|
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