The mysterious Of?p class and the magnetic O-star θ1 Ori C: confronting observations

Abstract

In recent years, the stars of the Of?p category have revealed a wealth of peculiar phenomena: varying line proles, photometric changes, and X-ray overluminosity are only a few of their characteristics. Here we review their physical properties to facilitate comparisons among the Galactic members of this class. As one of them has been proposed to resemble the magnetic oblique rotator θ1 Ori C, though with a longer period, this latter object is also included in our study to illuminate its similarities and differences with the Of?p category.