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Atomic diffusion an...
Atomic diffusion and mixing in old stars VI. The lithium content of M30
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- Gruyters, Pieter (författare)
- Uppsala University,Lund University,Lunds universitet,Uppsala universitet,Teoretisk astrofysik,Lund Observ, Box 43, S-22100 Lund, Sweden.,Astronomi - Har omorganiserats,Institutionen för astronomi och teoretisk fysik - Har omorganiserats,Naturvetenskapliga fakulteten,Lund Observatory - Has been reorganised,Department of Astronomy and Theoretical Physics - Has been reorganised,Faculty of Science
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- Lind, Karin (författare)
- Uppsala University,Uppsala universitet,Observationell astrofysik
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- Richard, Olivier (författare)
- Univ Montpellier, CNRS, LUPM, CC072,Pl E Bataillon, F-34095 Montpellier, France.,University of Montpellier
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- Grundahl, Frank (författare)
- Aarhus Univ, Dept Phys & Astron, Stellar Astrophys Ctr, Ny Munkegade 120, DK-8000 Aarhus C, Denmark.,Aarhus University
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- Asplund, Martin (författare)
- Australian Natl Univ, Mt Stromlo Observ, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia.,Australian National University
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- Casagrande, Luca (författare)
- Australian Natl Univ, Mt Stromlo Observ, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia.,Australian National University
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- Charbonnel, Corinne (författare)
- Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland.;Univ Toulouse, CNRS UMR 5277, IRAP, 14 Ave E Belin, F-31400 Toulouse, France.,University of Geneva,University of Toulouse
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- Milone, Antonino (författare)
- Australian Natl Univ, Mt Stromlo Observ, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia.,Australian National University
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- Primas, Francesca (författare)
- European So Observ, D-85748 Garching, Germany.,European Southern Observatory
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- Korn, Andreas J. (författare)
- Uppsala University,Uppsala universitet,Teoretisk astrofysik
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(creator_code:org_t)
- 2016-04-13
- 2016
- Engelska.
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 589
- Relaterad länk:
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http://dx.doi.org/10...
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https://urn.kb.se/re...
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https://doi.org/10.1...
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https://lup.lub.lu.s...
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Abstract
Ämnesord
Stäng
- Context. The prediction of the Planck-constrained primordial lithium abundance in the Universe is in discordance with the observed Li abundances in warm Population II dwarf and subgiant stars. Among the physically best motivated ideas, it has been suggested that this discrepancy can be alleviated if the stars observed today had undergone photospheric depletion of lithium.Aims. The cause of this depletion is investigated by accurately tracing the behaviour of the lithium abundances as a function of effective temperature. Globular clusters are ideal laboratories for such an abundance analysis as the relative stellar parameters of their stars can be precisely determined.Methods. We performed a homogeneous chemical abundance analysis of 144 stars in the metal-poor globular cluster M30, ranging from the cluster turnoff point to the tip of the red giant branch. Non-local thermal equilibrium (NLTE) abundances for Li, Ca, and Fe were derived where possible by fitting spectra obtained with VLT/FLAMES-GIRAFFE using the quantitative-spectroscopy package SME. Stellar parameters were derived by matching isochrones to the observed V vs. V I colour-magnitude diagram. Independent effective temperatures were obtained from automated profile fitting of the Balmer lines and by applying colour-T-eff calibrations to the broadband photometry.Results. Li abundances of the turno ff and early subgiant stars form a thin plateau that is broken off abruptly in the middle of the SGB as a result of the onset of Li dilution caused by the first dredge-up. Abundance trends with effective temperature for Fe and Ca are observed and compared to predictions from stellar structure models including atomic diffusion and ad hoc additional mixing below the surface convection zone. The comparison shows that the stars in M30 are affected by atomic diffusion and additional mixing, but we were unable to determine the efficiency of the additional mixing precisely. This is the fourth globular cluster (after NGC6397, NGC6752, and M4) in which atomic diffusion signatures are detected. After applying a conservative correction (T6.0 model) for atomic diffusion, we find an initial Li abundance of A(Li) = 2.48 +/- 0.10 for the globular cluster M30. We also detected a Li-rich SGB star with a Li abundance of A(Li) = 2.39. The finding makes Li-rich mass transfer a likely scenario for this star and rules out models in which its Li enhancement is created during the RGB bump phase.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- techniques: spectroscopic
- stars: abundances
- stars: atmospheres
- globular clusters: individual: M 30
- stars: Population II
- stars: fundamental parameters
- globular clusters: individual: M 30
- stars: abundances
- stars: atmospheres
- stars: fundamental parameters
- stars: Population II
- techniques: spectroscopic
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Gruyters, Pieter
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Lind, Karin
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Richard, Olivier
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Grundahl, Frank
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Asplund, Martin
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Casagrande, Luca
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Charbonnel, Cori ...
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Milone, Antonino
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Primas, Francesc ...
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Korn, Andreas J.
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