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arXiv · 2511.08675

The binary landscape of massive stars at low $Z$: Insights from the BLOeM Campaign

J. I. Villaseñor·H. Sana·J. Bodensteiner·N. Britavskiy·L. R. Patrick·T. Shenar·the BLOeM Collaboration
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Abstract

We present an overview of our recent results from the BLOeM campaign in the Small Magellanic Cloud ($Z=0.2\,{\rm Z}_{\odot}$). Using nine-epoch VLT/FLAMES spectroscopy, we investigated the multiplicity of 929 massive stars. Our findings reveal contrasting binary properties across evolutionary stages: O-type stars show an intrinsic close-binary fraction of $70\%$, and early B-type dwarfs/giants reach ${\sim80}\%$, exceeding higher-metallicity samples. In contrast, B0-B3 supergiants drop to ${\sim40}\%$, and A-F supergiants to ${\sim8}\%$; intrinsic variability likely inflates the latter, so the true multiplicity may be lower. OBe stars display distinct binary properties consistent with a post-interaction origin. These results have profound implications for massive-star evolution at low metallicity, including the production of exotic transients, gravitational-wave progenitors, and ionising radiation in the early Universe.

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J. I. Villaseñor, H. Sana, J. Bodensteiner, N. Britavskiy, L. R. Patrick, T. Shenar, the BLOeM Collaboration. 2025-11-11. The binary landscape of massive stars at low $Z$: Insights from the BLOeM Campaign. https://arxiv.org/abs/2511.08675

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