Mahy, L. ; Lanthermann, C. ; Gosset, E. ; Hutsemékers, D. ; Kluska, J. ; Lobel, A. ; Reggiani, M. ; Sana, H.

published in Massive Stars Near and Far, Edited by J. Mackey, J.S. Vink and N. St-Louis. Proceedings of the International Astronomical Union, held 8-13 May 2022 in Ballyconnell, Ireland. Cambridge University Press, 2024, 361, pp. 273-278 (2024)

Abstract: Luminous Blue Variable stars (LBVs) are rare and enigmatic. Often cited as evolu- tionary stages in the single-star evolution, the idea that binary evolution produces the LBV state was already considered, 30 years ago. It is now commonly accepted that a significant part of massive stars are born in multiple systems. One aspect that also emerged is that massive stars have on average at least two com- panions, i.e. they are triples. This immediately implies that a number of LBVs should have evolved as part of multiple systems. While some LBVs are confirmed as binaries, different methods were used to derive their multiplicity, with different results. We report on a systematic search for multiplicity using spec- troscopy, interferometry in a sample of 20 LBVs. Spectroscopy provides us with a bias-corrected binary fraction of 62+38-24 %, and a percentage of 50 − 70% is found from interferometry. This has a high impact on the way that these objects might be formed.

DOI: 10.1017/S1743921322002848