AAS 200th meeting, Albuquerque, NM, June 2002
Session 9. Open Clusters and Their Constituents
Display, Monday, June 3, 2002, 9:20am-6:30pm, SW Exhibit Hall

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[9.05] Beryllium Abundances in F and G Dwarfs in Six Open Clusters from Keck/HIRES Observations

A. M. Boesgaard, E. Armengaud (Univ. of Hawaii, Manoa), J. R. King (UNLV)

We have made observations of the resonance doublet of Be II of 81 F and G dwarfs in six open clusters with the Keck I telescope and HIRES. The spectral resolution is ~45,000 and the signal-to-noise ratios are 40 - 100. Abundances of Be have been determined by spectral synthesis using the most recent version of MOOG which contains modern UV opacities. For the F dwarfs there is a Be dip similar to the Li dip in the temperature range 6300 - 6800 K for the Hyades, Coma, and Praesepe clusters. These clusters have ages of 5-8 x 108 yr. The Be dip is not as deep as the Li dip: Be is down by factors of 5-10 while Li is down by 2 orders of magnitude and more. The young clusters, Pleiades and Alpha Per (ages 5-7 x 107 yr), show no Be dip in the mid-F stars; there is no Li dip in clusters this young either. The Be abundance is high (no Be depletion) in the G dwarfs in all the clusters even though Li depletions are more than a factor of 100. In the temperature range 5900 - 6850 K there is a correlation of Li and Be for all the clusters. This correlation is well-matched by the predictions of stellar rotation models.

This work has been supported by the National Science Foundation.

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.