Grids of stellar models with rotation VII: models from 0.8 to 300 M-circle dot at supersolar metallicity (Z=0.020)

• Main Authors: Yusof, Norhasliza, Hirschi, Raphael, Eggenberger, Patrick, Ekstrom, Sylvia, Georgy, Cyril, Sibony, Yves, Crowther, Paul A., Meynet, Georges, Kassim, Hasan Abu, Harun, Wan Aishah Wan, Maeder, Andre, Groh, Jose H., Farrell, Eoin, Murphy, Laura
• Format: Article
• Published: Oxford University Press 2022
• Subjects: Q Science (General); QC Physics
• Online Access: http://eprints.um.edu.my/33358/

We present a grid of stellar models at supersolar metallicity (Z = 0.020) extending the previous grids of Geneva models at solar and sub-solar metallicities. A metallicity of Z = 0.020 was chosen to match that of the inner Galactic disc. A modest increase of 43 per cent (= 0.02/0.014) in metallicity compared to solar models means that the models evolve similarly to solar models but with slightly larger mass-loss. Mass-loss limits the final total masses of the supersolar models to 35 M-circle dot even for stars with initial masses much larger than 100 M-circle dot. Mass-loss is strong enough in stars above 20 K for rotating stars (25 M-circle dot for non-rotating stars) to remove the entire hydrogen-rich envelope. Our models thus predict SNII below 20 M-circle dot for rotating stars (25 M-circle dot for non-rotating stars) and SNIb (possibly SNIc) above that. We computed both isochrones and synthetic clusters to compare our supersolar models to the Westerlund 1 (Wd1) massive young cluster. A synthetic cluster combining rotating and non-rotating models with an age spread between log(10)(age/yr) = 6.7 and 7.0 is able to reproduce qualitatively the observed populations of WR, RSG, and YSG stars in Wd1, in particular their simultaneous presence at log(10) (L/L-circle dot) = 5-5.5. The quantitative agreement is imperfect and we discuss the likely causes: synthetic cluster parameters, binary interactions, mass-loss and their related uncertainties. In particular, mass-loss in the cool part of the HRD plays a key role.