The Dependence of Convective Core Overshooting on Stellar Mass: A Semi-empirical Determination Using the Diffusive Approach with Two Different Element Mixtures

DOI: 
10.3847/1538-4357/aa8770
Publication date: 
01/11/2017
Main author: 
Claret, Antonio
IAA authors: 
Claret, Antonio
Authors: 
Claret, Antonio;Torres, Guillermo
Journal: 
The Astrophysical Journal
Refereed: 
Yes
Publication type: 
Article
Volume: 
849
Pages: 
18
Abstract: 

Convective core overshooting has a strong influence on the evolution of stars of moderate and high mass. Studies of double-lined eclipsing binaries and stellar oscillations have renewed interest in the possible dependence of overshooting on stellar mass, which has been poorly constrained by observations so far. Here, we have used a sample of 29 well-studied double-lined eclipsing binaries in key locations of the H─R diagram to establish the explicit dependence of {f}<SUB>{ov</SUB>} on mass, where {f}<SUB>{ov</SUB>} is the free parameter in the diffusive approximation to overshooting. Measurements of the masses, radii, and temperatures of the binary components were compared against stellar evolution calculations based on the MESA code to infer semi-empirical values of {f}<SUB>{ov</SUB>} for each component. We find a clear mass-dependence such that {f}<SUB>{ov</SUB>} rises sharply from zero in the range 1.2{--}2.0 {M}<SUB>ȯ </SUB>, and levels off thereafter up to the 4.4 {M}<SUB>ȯ </SUB> limit of our sample. Tests with two different element mixtures indicate the trend is the same, and we find it to also be qualitatively similar to the one established in our previous study with the classical step-function implementation of overshooting characterized by the free parameter {α }<SUB>{ov</SUB>}. Based on these measurements, we infer an approximate relationship between the two overshooting parameters of {α }<SUB>{ov</SUB>}/{f}<SUB>{ov</SUB>}=11.36+/- 0.22, with a possible dependence on stellar properties.

Database: 
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2017ApJ...849...18C/abstract
ADS Bibcode: 
2017ApJ...849...18C
Keywords: 
binaries: eclipsing;convection;stars: evolution;stars: interiors