Stellar age determination in the Mass-Luminosity Plane

Abstract

The ages of stars have historically relied on isochrone fitting of standardised grids of models. While these stellar models have provided key constraints on observational samples of massive stars, they inherit many systematic uncertainties, mainly in the internal mixing mechanisms applied throughout the grid, fundamentally undermining the isochrone method. In this work, we utilise the M-L plane of Higgins & Vink as a method of determining stellar age, with mixing-corrected models applying a calibrated core overshooting alpha_ov and rotation rate to fit the observational data. We provide multiple test-beds to showcase our new method, while also providing comparisons to the commonly-used isochrone method, highlighting the dominant systematic errors. We reproduce the evolution of individual O stars, and analyse the wider sample of O and B supergiants from the VLT-FLAMES Tarantula Survey, providing dedicated models with estimates for alpha_ov, Omega/Omega_crit, and ultimately stellar ages. The M-L plane highlights a large discrepancy in the spectroscopic masses of the O supergiant sample. Furthermore the M-L plane also demonstrates that the evolutionary masses of the B supergiant sample are inappropriate. Finally, we utilise detached eclipsing binaries, VFTS 642 and VFTS 500, and present their ages resulting from their precise dynamical masses, offering an opportunity to constrain their interior mixing. For the near-TAMS system, VFTS 500, we find that both components require a large amount of core overshooting (alpha_ov ~ 0.5), implying an extended main-sequence width. We hence infer that the vast majority of B supergiants are still burning hydrogen in their cores.

13 pages, 13 figures. Accepted for publication in MNRAS. Comments welcome

References in corpus (16)

• The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 Msun stellar mass limit
• BONNSAI: a Bayesian tool for comparing stars with stellar evolution models
• The Tarantula Massive Binary Monitoring: I. Observational campaign and OB-type spectroscopic binaries
• The spectroscopic Hertzsprung-Russell diagram of Galactic massive stars
• Populations of rotating stars III. SYCLIST, the new Geneva Population Synthesis code
• Photometric detection of internal gravity waves in upper main-sequence stars. II. Combined TESS photometry and high-resolution spectroscopy
• The dependence of convective core overshooting on stellar mass: semi-empirical determination using the diffusive approach with two different element mixtures
• Mixing by overshooting and rotation in intermediate mass stars
• The VLT-FLAMES Tarantula Survey XIX. B-type Supergiants - Atmospheric parameters and nitrogen abundances to investigate the role of binarity and the width of the main sequence
• Confronting uncertainties in stellar physics: calibrating convective overshooting with eclipsing binaries
• The Tarantula Massive Binary Monitoring: III. Atmosphere analysis of double-lined spectroscopic systems
• Rotating massive O stars with non-spherical 2D winds
• Convective core entrainment in 1D main sequence stellar models
• Multiple stellar populations in NGC 1866. New clues from Cepheids and Colour-Magnitude Diagram
• High-mass pulsators in eclipsing binaries observed using TESS
• A modern study of HD166734: a massive supergiant system

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• Clumping and X-Rays in cooler B supergiant stars