The IACOB project XIX. Revisiting massive-star evolution with empirical TAMS constraints: updated models, overshoot calibration, and the population of blue supergiants
Abstract
Massive stars play a fundamental role in the evolution of the Universe. Yet, several physical processes governing their evolution remain poorly constrained. Notably, the main-sequence width is sensitive to the convective boundary mixing efficiency; it becomes necessary to account for binary interactions to explain some observed properties of massive-star populations. We constrain single-star models using recent observations of massive Galactic stars from the IACOB database. We use the latest proposed empirical location of the TAMS to calibrate the convective boundary mixing efficiency, and use this calibration to test single-star evolution by comparing various model predictions to the observed populations of the IACOB sample. We compute several GENEC grids with various overshoot calibrations, angular momentum transport (AMT) treatments, initial masses and velocities. Finally, we generate synthetic populations from the tracks with SYCLIST and perform a direct comparison with the observed population. The calibrated models at slow rotation reproduce the empirical TAMS location. We find that a mass-dependent overshoot efficiency is required to fit the observational constraints. The overall rotational properties of the observed populations are well reproduced with single-star models, independently of the AMT assumptions. Models accounting only for hydrodynamical instabilities are successful at reproducing the rotational properties, unlike previous genec grids, which we attribute to the choice of winds prescription. Although the empirical TAMS of slow rotators is well reproduced, we find that models are unsuccessful at explaining the velocity dependence of the TAMS location observed in the IACOB sample. Finally, we find that single-star models fail at explaining the population of blue supergiants to the right of the TAMS location.
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BibTeX
@misc{sciarini2026iacob,
title = {{The IACOB project XIX. Revisiting massive-star evolution with empirical TAMS constraints: updated models, overshoot calibration, and the population of blue supergiants}},
author = {Luca Sciarini and Abel de Burgos and Sophie Rosu and Sylvia Ekström and Sergio Simón-Díaz and Cyril Georgy},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2607.29650},
eprint = {2607.29650},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.29650},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The IACOB project XIX. Revisiting massive-star evolution with empirical TAMS constraints: updated models, overshoot calibration, and the population of blue supergiants
AU - Luca Sciarini
AU - Abel de Burgos
AU - Sophie Rosu
AU - Sylvia Ekström
AU - Sergio Simón-Díaz
AU - Cyril Georgy
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2607.29650
UR - https://arxiv.org/abs/2607.29650
AB - Massive stars play a fundamental role in the evolution of the Universe. Yet, several physical processes governing their evolution remain poorly constrained. Notably, the main-sequence width is sensitive to the convective boundary mixing efficiency; it becomes necessary to account for binary interactions to explain some observed properties of massive-star populations. We constrain single-star models using recent observations of massive Galactic stars from the IACOB database. We use the latest proposed empirical location of the TAMS to calibrate the convective boundary mixing efficiency, and use this calibration to test single-star evolution by comparing various model predictions to the observed populations of the IACOB sample. We compute several GENEC grids with various overshoot calibrations, angular momentum transport (AMT) treatments, initial masses and velocities. Finally, we generate synthetic populations from the tracks with SYCLIST and perform a direct comparison with the observed population. The calibrated models at slow rotation reproduce the empirical TAMS location. We find that a mass-dependent overshoot efficiency is required to fit the observational constraints. The overall rotational properties of the observed populations are well reproduced with single-star models, independently of the AMT assumptions. Models accounting only for hydrodynamical instabilities are successful at reproducing the rotational properties, unlike previous genec grids, which we attribute to the choice of winds prescription. Although the empirical TAMS of slow rotators is well reproduced, we find that models are unsuccessful at explaining the velocity dependence of the TAMS location observed in the IACOB sample. Finally, we find that single-star models fail at explaining the population of blue supergiants to the right of the TAMS location.
ER -