The Gaia-ESO survey: A lithium depletion boundary age for NGC 2232

Binks, A S; Jeffries, Robin D; Jackson, Richard J; Franciosini, E; Sacco, G G; Bayo, A; Magrini, L; Randich, S; Arancibia-Silva, J; Bergemann, M; Bragaglia, A; Gilmore, G; Gonneau, A; Hourihane, A; Jofré, P; Korn, A J; Morbidelli, L; Prisinzano, L; Worley, C C; Zaggia, S

Abstract

Astrometry and photometry from {\it Gaia} and spectroscopic data from the {\it Gaia}-ESO Survey (GES) are used to identify the lithium depletion boundary (LDB) in the young cluster NGC 2232. A specialised spectral line analysis procedure was used to recover the signature of undepleted lithium in very low luminosity cluster members. An age of $38\pm 3$ Myr is inferred by comparing the LDB location in absolute colour-magnitude diagrams (CMDs) with the predictions of standard models. This is more than twice the age derived from fitting isochrones to low-mass stars in the CMD with the same models. Much closer agreement between LDB and CMD ages is obtained from models that incorporate magnetically suppressed convection or flux-blocking by dark, magnetic starspots. The best agreement is found at ages of $45-50$\,Myr for models with high levels of magnetic activity and starspot coverage fractions $>50$ per cent, although a uniformly high spot coverage does not match the CMD well across the full luminosity range considered.

Citation

Binks, A. S., Jeffries, R. D., Jackson, R. J., Franciosini, E., Sacco, G. G., Bayo, A., …Zaggia, S. (2021). The Gaia-ESO survey: A lithium depletion boundary age for NGC 2232. Monthly Notices of the Royal Astronomical Society, 505(1), 1280-1292

• Journal Article Type: Article
• Acceptance Date: May 3, 2021
• Online Publication Date: May 12, 2021
• Publication Date: 2021-07
• Publicly Available Date: May 30, 2023
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 505
• Issue: 1
• Pages: 1280-1292
• Keywords: stars: kinematics and dynamics, stars: late-type, stars: pre-main-sequence, solar neighbourhood
• Publisher URL: https://academic.oup.com/mnras/article/505/1/1280/6274699?login=true