Multiplicity of Massive Stars at Low Metallicity: Early Results from the BLOeM Campaign
arXiv:2607.27395 · doi:10.18727/0722-6691/5417
The BLOeM campaign presents the first large‑scale spectroscopic survey of 929 massive stars in the Small Magellanic Cloud, revealing a high intrinsic binary fraction (>70%) among main‑sequence stars at low metallicity and a decline in evolved objects.
Abstract
Massive stars at low metallicity (Z) play a central role in shaping the high-redshift Universe, yet their multiplicity remains poorly constrained. The Binarity at Low Metallicity (BLOeM) campaign is a two-year survey of 929 stars in the Small Magellanic Cloud with the Fibre Large Array Multi Element Spectrograph (FLAMES) instrument at ESO's Very Large Telescope, providing the first large-scale spectroscopic monitoring of massive stars at low Z (1/5 solar). Analysis of the initial nine epochs reveals high intrinsic binary fractions (>70%) on the main sequence and a steep decline in evolved objects. Analysis of the full dataset will yield orbital solutions, identify black-hole companions, and allow a derivation of the initial mass function for single and binary stars at low Z.
5 pages, 3 figures; published in The Messenger (ESO)