Convective Core Mixing: a Metallicity Dependence?

Abstract

The main scope of this paper is to investigate the possible existence of a metallicity dependence of the overshooting from main sequence stars turbulent cores. We focus on objects with masses in the range ~2.5 Msol - ~25 Msol. Basically, evolutionary time scale ratios are compared with star numbers ratios on the main sequence. Star populations are synthesized using grids of evolutionary tracks computed with various overshooting amounts. Observational material is provided by the large and homogeneous photometric database of OGLE 2 project for the Magellanic clouds. Attention is paid to the study of uncertainties: distance modulus, intergalactic and interstellar reddening, IMF slope and average binarity rate. Rotation and chemical composition gradient are also considered. The result for the overshooting distance is l_over(SMC)= 0.40 +0.12-0.06 Hp (Z=0.004) and l_over(LMC)= 0.10+0.17-0.10 Hp (Z=0.008) suggesting a possible dependence of the extent of the mixed central regions with metallicity within the considered mass range. Unfortunately it is not yet possible to fully disentangle effects of mass and chemical composition.

13 pages, 8 figures, accepted in Astronomy & Astrophysics

References in corpus (5)

• Stellar evolution with rotation VII: Low metallicity models and the blue to red supergiant ratio in the SMC
• Magellanic Cloud Structure from Near-IR Surveys I: The Viewing Angles of the LMC
• The Line-of-Sight Depth of Populous Clusters in the Small Magellanic Cloud
• The Helium content and age of the Hyades: Constraints from five binary systems and Hipparcos parallaxes
• Background galaxies as reddening probes throughout the Magellanic Clouds

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