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The Gaia-ESO Survey: A lithium-rotation connection at 5 Myr


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Publication Date: 2016-04-29

Journal Title: Astronomy & Astrophysics

Publisher: EDP Sciences

Language: English

Type: Article

Metadata: Show full item record

Citation: Bouvier, J., Lanzafame, A. C., Venuti, L., Klutsch, A., Jeffries, R., Frasca, A., Moraux, E., et al. (2016). The Gaia-ESO Survey: A lithium-rotation connection at 5 Myr?. Astronomy & Astrophysics

Description: This is the author accepted manuscript. The final version is available from EDP Sciences via http://dx.doi.org/10.1051/0004-6361/201628336

Abstract: Context. The evolution of lithium abundance in cool dwarfs provides a unique probe of non-standard processes in stellar evolution. Aims. We investigate here the lithium content of young low-mass stars in the 5 Myr-old star forming region NGC 2264 and its relationship with rotation. Methods. We combine lithium equivalent width measurements (EW(Li)) from the Gaia-ESO Survey with the determination of rotational periods from the CSI 2264 survey. We consider only bona fide non accreting cluster members in order to minimize uncertainties on EW(Li). Results. We report the existence of a relationship between lithium content and rotation in NGC 2264 at an age of 5 Myr. The Li-rotation connection is seen over a restricted temperature range ( Teff=3800–4400 K) where fast rotators are Li-rich compared to slow ones. This correlation is similar to, albeit of lower amplitude than, the Li-rotation connection previously reported for K dwarfs in the 125 Myr-old Pleiades cluster. We investigate whether the non-standard pre-main sequence models developed so far to explain the Pleiades results, which are based on episodic accretion, pre-main sequence core-envelope decoupling, and/or radius inflation due to enhanced magnetic activity, can account for an early development of the Li-rotation connection. While radius inflation appears to be the most promising possibility, each of these models has issues. We therefore also discuss external causes that might operate during the first few Myr of pre-main sequence evolution, such as planet engulfment and/or steady disk accretion, as possible candidates for the common origin for Li-excess and fast rotation in young low-mass pre-main sequence stars. Conclusions. The emergence of a connection between lithium content and rotation rate at such an early age as 5 Myr suggests a complex link between accretion processes, early angular momentum evolution, and possibly planet formation, which likely impacts early stellar evolution and still is to be fully deciphered.

Keywords: stars: abundances, stars: pre-main sequence, stars: rotation, open clusters and associations: individual: NGC 2264

Sponsorship: J. Bouvier and E. Moraux thank the staff of the Osservatorio Astrofisico di Catania for their kind hospitality in automn of 2015. They acknowledge the Agence Nationale pour la Recherche program ANR 2010 JCJC 0501 1 “DESC (Dynamical Evolution of Stellar Clusters)” for the funding of their stay at OACT during which this study was performed. This study was also supported by the Agence Nationale pour la Recherche program ANR 2011 Blanc SIMI 5-6 020 01 “Toupies (Towards understanding the spin evolution of stars)”. A. Bayo acknowledges financial support from the Proyecto Fondecyt Iniciación 11140572. S.G. Sousa acknowledges the support from FCT through Investigador FCT contract of reference IF/00028/2014. E. Delgado Mena acknowledges the support from FCT in the form of the grant SFRH/BPD/76606/2011. S.G.S. and E.D.M. also acknowledge the support from FCT through the project PTDC/FIS-AST/7073/2014 Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 188.B-3002. These data products have been processed by the Cambridge Astronomy Survey Unit (CASU) at the Institute of Astronomy, University of Cambridge, and by the FLAMES/UVES reduction team at INAF/Osservatorio Astrofisico di Arcetri. These data have been obtained from the Gaia-ESO Survey Data Archive, prepared and hosted by the Wide Field Astronomy Unit, Institute for Astronomy, University of Edinburgh, which is funded by the UK Science and Technology Facilities Council. This work was partly supported by the European Union FP7 programme through ERC grant number 320360 and by the Leverhulme Trust through grant RPG-2012-541. We acknowledge the support from INAF and Ministero dell’ Istruzione, dell’ Uni- versità’ e della Ricerca (MIUR) in the form of the grant “Premiale VLT 2012” and “The Chemical and Dynamical Evolution of the Milky Way and the Local Group Galaxies (prot. 2010LY5N2T). The results presented here benefit from discussions held during the Gaia-ESO workshops and conferences supported by the ESF (European Science Foundation) through the GREAT Research Network Programme.

Identifiers:

This record's URL: http://dx.doi.org/10.1051/0004-6361/201628336https://www.repository.cam.ac.uk/handle/1810/255907





Autor: Bouvier, J.Lanzafame, A. C.Venuti, L.Klutsch, A.Jeffries, R.Frasca, A.Moraux, E.Biazzo, K.Messina, S.Micela, G.Randich, S.Stauffer

Fuente: https://www.repository.cam.ac.uk/handle/1810/255907



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