# The Gaia-ESO Survey: lithium depletion in the Gamma Velorum cluster and inflated radii in low-mass pre-main-sequence stars

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Publication Date: 2017-01-01

Journal Title: Monthly Notices of the Royal Astronomical Society

Publisher: Oxford University Press

Volume: 464

Issue: 2

Pages: 1456-1465

Language: English

Type: Article

This Version: VoR

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Citation: Jeffries, R., Jackson, R., Franciosini, E., Randich, S., Barrado, D., Frasca, A., Klutsch, A., et al. (2017). The Gaia-ESO Survey: lithium depletion in the Gamma Velorum cluster and inflated radii in low-mass pre-main-sequence stars. Monthly Notices of the Royal Astronomical Society, 464 (2), 1456-1465. https://doi.org/10.1093/mnras/stw2458

Abstract: We show that non-magnetic models for the evolution of pre-main-sequence (PMS) stars $\textit{cannot}$ simultaneously describe the colour–magnitude diagram (CMD) and the pattern of lithium depletion seen in the cluster of young, low-mass stars surrounding $\gamma$$^2$ Velorum. The age of 7.5 ± 1 Myr inferred from the CMD is much younger than that implied by the strong Li depletion seen in the cluster M-dwarfs, and the Li depletion occurs at much redder colours than predicted. The epoch at which a star of a given mass depletes its Li and the surface temperature of that star are both dependent on its radius. We demonstrate that if the low-mass stars have radii ~10 per cent larger at a given mass and age, then both the CMD and the Li-depletion pattern of the Gamma Velorum cluster are explained at a common age of $\simeq$18–21 Myr. This radius inflation could be produced by some combination of magnetic suppression of convection and extensive cool starspots. Models that incorporate radius inflation suggest that PMS stars, similar to those in the Gamma Velorum cluster, in the range 0.2 < $M$/$M_\odot$ < 0.7, are at least a factor of 2 older and ~7 per cent cooler than previously thought and that their masses are much larger (by >30 per cent) than inferred from conventional, non-magnetic models in the Hertzsprung–Russell diagram. Systematic changes of this size may be of great importance in understanding the evolution of young stars, disc lifetimes and the formation of planetary systems.

Keywords: stars: evolution, stars: low-mass, stars: magnetic field, stars: pre-main-sequence, starspots, open clusters and associations: general

Sponsorship: RDJ and RJJ acknowledge support from the UK Science and Technology Facilities Council (STFC). Based on data products from observations made with European Southern Observatory (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 the Istituto Nazionale di Astrofisica (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 STFC. This publication makes use of data products from the TwoMicron All-Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. This work was partly supported by the European Union FP7 programme through European Research Council (ERC) grant number 320360 and by the Leverhulme Trust through grant RPG-2012- 541. We acknowledge the support from the INAF and Ministero dell’ Istruzione, dell’ Universita’ e della Ricerca (MIUR) in the ` form of the grant ‘ Premiale VLT 2012’. This research was partially supported by the INAF through a PRIN-2014 grant. The results presented here benefit from discussions held during the Gaia-ESO workshops and conferences supported by the European Science Foundation (ESF) through the Gaia Research for European Astronomy Training (GREAT) Research Network Programme.

Embargo Lift Date: 2100-01-01

Identifiers:

External DOI: https://doi.org/10.1093/mnras/stw2458

This record's URL: https://www.repository.cam.ac.uk/handle/1810/263545

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Autor: Jeffries, RDJackson, RJFranciosini, ERandich, SBarrado, DFrasca, AKlutsch, ALanzafame, ACPrisinzano, LSacco, GG Gilmore, Gerard Fr

Fuente: https://www.repository.cam.ac.uk/handle/1810/263545

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