# The VLT-FLAMES survey of massive stars: Wind properties and evolution of hot massive stars in the LMC

## TL;DR

This study analyzes optical spectra of 28 massive stars in the Large Magellanic Cloud to determine their properties, evolutionary status, and wind characteristics, revealing effects of rotation and metallicity on their evolution.

## Contribution

It introduces an automated method combining FASTWIND and PIKAIA for stellar parameter determination and provides new insights into the evolution and wind properties of LMC massive stars.

## Key findings

- Evidence for rotationally-enhanced mixing in helium-enriched stars.
- Mass-loss rates are intermediate between Galactic and SMC stars.
- Good agreement between observed mass-loss and theoretical predictions at LMC metallicity.

## Abstract

[Abridged] We have studied the optical spectra of 28 O- and early B-type stars in the Large Magellanic Cloud, 22 of which are associated with the young star-forming region N11. Stellar parameters are determined using an automated fitting method, combining the stellar atmosphere code FASTWIND with the genetic-algorithm optimisation routine PIKAIA. Results for stars in the LH9 and LH10 associations of N11 are consistent with a sequential star formation scenario, in which activity in LH9 triggered the formation of LH10. Our sample contains four stars of spectral type O2, of which the hottest is found to be ~49-54 kK (cf. ~45-46 kK for O3 stars). The masses of helium-enriched dwarfs and giants are systematically lower than those implied by non-rotating evolutionary tracks. We interpret this as evidence for efficient rotationally-enhanced mixing, leading to the surfacing of primary helium and to an increase of the stellar luminosity. This result is consistent with findings for SMC stars by Mokiem et al. For bright giants and supergiants no such mass-discrepancy is found, implying that these stars follow tracks of modestly (or non-)rotating objects. Stellar mass-loss properties were found to be intermediate to those found in massive stars in the Galaxy and the SMC, and comparisons with theoretical predictions at LMC metallicity yielded good agreement over the luminosity range of our targets, i.e. 5.0 < log L/L(sun) < 6.1.