Caballero, J. A., Bouy, H., Lillo Box, J. 2016. An upper limit to the mass of a close companion candidate to σ Ori E. Observatory 136, 1254, 226-231
The famous, very young, helium rich, magnetically active, radio and X-ray emitter, short-period rotationally variable, spectroscopically peculiar star a Ori E may have a close late-type stellar companion, which could explain flaring activity observed in some sigma Ori E X-ray light-curves. In 2009, Bouy et al. announced the detection of a faint companion candidate in the Ks band at 0.330 arcsec (13o AU) from the B2 Vp primary. Here, we carry out z’-band lucky imaging with AstraLux at the 2.2 m Calar Alto telescope in an attempt to constrain the properties of the companion candidate to a Ori E. We impose a maximum mass of 2.0(-0.1)(+0.2) M-circle dot and an earliest spectral type of K2 +/- 1, which leaves the door open to a new, inexpensive, near-infrared, adaptive-optics study.