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Pinning Down Gravitational Settling

Andreas J. Korn·Nikolai Piskunov·Frank Grundahl·Paul Barklem·Bengt Gustafsson
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Abstract

We analyse high-resolution archival UVES data of turnoff and subgiant stars in the nearby globular cluster NGC 6397 ([Fe/H] = -2). Balmer-profile analyses are performed to derive reddening-free effective temperatures. Due to the limited S/N and uncertainties related to blaze removal, we find the data quality insufficient to exclude the existence of gravitational settling. If the newly derived effective temperatures are taken as a basis for an abundance analysis, the photospheric iron (Fe II) abundance in the turnoff stars is 0.11 dex lower than in the (well-mixed) subgiants.

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Andreas J. Korn, Nikolai Piskunov, Frank Grundahl, Paul Barklem, Bengt Gustafsson. 2006-08-16. Pinning Down Gravitational Settling. https://doi.org/10.1007/978-3-540-34136-9_95

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