AAS 196th Meeting, June 2000
Session 35. High Resolution Spectroscopy at Visible and Ultraviolet Wavelengths
Topical Session Oral, Wednesday, June 7, 2000, 8:30-10:00am, 10:45am-12:30pm, 2:30-4:00pm, 4:15-6:00pm, Highland A/K

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[35.16] Keck Observations of Lithium in Open Star Clusters

B. F. Jones (UCO/Lick)

Lithium is destroyed at a relatively low temperature (2.5 million K), This temperature is reached at the base of the convective zone during pre-main sequence contraction for stars slightly less massive than the Sun, and these stars show lithium depletion increasing with decreasing mass. Theory suggests that stars newly arrived on the main sequence show show little spread in lithium abundance at a given mass, but that is not the case. Moreover, theory also suggests that solar mass stars should show little lithium depletion while on the main sequence, unless there is some additional mixing below the base of the convective zone. Old solar mass stars (i.e., the Sun) have heavily depleted lithium.

Observations of lithium in solar type stars of different ages and metallicities can give clues about mixing, both during pre-main sequence contraction, and during a star's lifetime on the main sequence. The new generation of large telescopes coupled with efficient high resolution spectrographs has allowed the observation of solar and later type stars in open clusters covering a wide range of ages and metallicities.

Over the last decade, an observational picture of main sequence lithium depletion and its (possible) relationship to angular momentum loss has begun to emerge. This talk will discuss these observations, as well touch on outstanding problems, such as the unexpected dispersion in lithium abundance at a given mass in young clusters, and the lithium-rotation connection.

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