WIYN Open Cluster Study LXXXV. Li in NGC 2243 -- Implications for Stellar and Galactic Evolution

Abstract

High-dispersion spectra in the Li 6708 Angstrom region have been obtained and analyzed in the old, metal-deficient cluster, NGC 2243. From Hydra spectra for 29 astrometric and radial-velocity members, we derive rotational velocities, as well as [Fe/H], [Ca/H], [Si/H], and [Ni/H] based on 17, 1, 1, and 3 lines, respectively. Using ROBOSPECT, an automatic equivalent width measurement program, we derive [Fe/H] = -0.54 +/- 0.11 (MAD), for an internal precision for the cluster [Fe/H] below 0.03 dex. Given the more restricted line set, comparable values for [Ca/H], [Si/H], and [Ni/H] are -0.48 +/- 0.19, -0.44 +/- 0.11, and -0.61 +/- 0.06, respectively. With E(B-V) = 0.055, appropriate isochrones imply (m-M) = 13.2 +/- 0.1 and an age of 3.6 +/- 0.2 Gyr. Using available VLT spectra and published Li abundances, we construct a Li sample of over 100 stars extending from the tip of the giant branch to 0.5 mag below the Li-dip. The Li-dip is well populated and, when combined with results for NGC 6819 and Hyades/Praesepe, implies a mass/metallicity slope of 0.4 solar-mass/dex for the high mass edge of the Li-dip. The A(Li) distribution among giants reflects the degree of Li variation among the turnoff stars above the Li-dip, itself a function of stellar mass and metallicity and strongly anticorrelated with a v_rot distribution that dramatically narrows with age. Potential implications of these patterns for the interpretation of Li among dwarf and giant field populations, especially selection biases tied to age and metallicity, are discussed.

24 pages; 12 figures; accepted for Astronomical Journal

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Cited by in corpus (9)

• The Gaia-ESO Survey: Galactic evolution of lithium from iDR6
• WIYN Open Cluster Study: The Old Open Cluster, NGC 188, and a Re-evaluation of Lithium-Richness Among Red Giants
• WIYN Open Cluster Study 89. M48 (NGC 2548) 2: Lithium Abundances in the 420 Myr Open Cluster M48 From Giants Through K Dwarfs
• The Gaia-ESO Survey: Lithium measurements and new curves of growth
• The Lithium Abundances from the Large Sky Area Multi-object Fiber Spectroscopic Telescope Medium-resolution Survey. I. The Method
• The behaviour of lithium at high metallicity in the Milky Way -- Selection effects in the samples and the possible role of atomic diffusion
• Lithium in Kepler Red Giants: Defining Normal and Anomalous
• A GALAH View of the Chemical Homogeneity and Ages of Stellar Strings Identified in Gaia
• A uvbyCaHbeta CCD Analysis of the Open Cluster Standard, M67,and its Relation to NGC 752