On the Binarity of LBV Stars

Martayan, C.; Lobel, A.; Baade, D.; Blomme, R.; Frémat, Y.; LeBouquin, J.-B.; Selman, F.; Girard, J.; Mérand, A.; Montagnier, G.; Patru, F.; Mawet, D.; Martins, F.; Rivinius, Th.; Štefl, S.; Zorec, J.; Semaan, T.; Mehner, A.; Kervella, P.; Sana, H.; Schödel, R.
Circumstellar Dynamics at High Resolution. Proceedings of a Joint ESP/Brazilian Workshop held at Foz do Iguacu, Brazil, 27 February-2 March, 2012. ASP Conference Proceedings, Vol. 464. Edited by A. Carciofi and Th. Rivinius. San Francisco: Astronomical Society of the Pacific, p.293 (2012).


We report on the binarity of luminous blue variable stars observed with a set of techniques and instruments. Among them, observations at high angular resolution with the VLT-NACO, the VLTI-AMBER and with spectrographs such as the VLT-XSHOOTER allowed us to find several LBV stars as binaries or having a potential companion. In particular the LBV Pistol Star clearly presents radial velocity variations and line profiles modifications (double peak appearance). In addition, the absorption component of the P Cygni lines varies as well with the time indicating a potential wind structure variability. Our observations also show directly for the first time a companion to at least one of the observed LBVs (HD 168625). This one seems to affect the environment of the system. This system is known to be surrounded by several rings similar to those of SN1987A, possibly indicating a future supernova occurrence for this Galactic object. These results show that Eta Car is no longer unique.