The Evolutionary Status of WN3/O3 Wolf-Rayet Stars
Abstract
As part of a multi-year survey for Wolf-Rayet stars in the Magellanic Clouds, we have discovered a new type of Wolf-Rayet star with both strong emission and absorption. While one might initially classify these stars as WN3+O3V binaries based on their spectra, such a pairing is unlikely given their faint visual magnitudes. Spectral modeling suggests effective temperatures and bolometric luminosities similar to those of other early-type LMC WNs but with mass-loss rates that are three to five times lower than expected. They additionally retain a significant amount of hydrogen, with nitrogen at its CNO-equilibrium value (10x enhanced). Their evolutionary status remains an open question. Here we discuss why these stars did not evolve through quasi-homogeneous evolution. Instead we suggest that based on a link with long-duration gamma ray bursts, they may form in lower metallicity environments. A new survey in M33, which has a large metallicity gradient, is underway.
Keywords
Cite
@article{arxiv.1701.08154,
title = {The Evolutionary Status of WN3/O3 Wolf-Rayet Stars},
author = {Kathryn F. Neugent and Phil Massey and D. John Hillier and Nidia I. Morrell},
journal= {arXiv preprint arXiv:1701.08154},
year = {2017}
}
Comments
The lives and death-throes of massive stars; Proceedings IAU Symposium No. 329, 2017; J.J. Eldridge, editor