On the Nature of the BeWD System Nova FQ Circinus

Abstract

The classical nova FQ Cir (Schaefer et al. 2026) has recently been shown to have a Be star donor, and has been identified as a High Mass Cataclysmic Variable (HMCV), with an orbital period of $\sim 2.04d$ (twice the 1.02d periodogram peak). Using the extensive OGLE optical archive, together with existing observations from ASAS-SN we instead find significant modulation between $\sim 50-60$~days and propose that the orbital period is likely closer to $\sim 62d$. We interpret the low amplitude 1.02 d modulation as a non-radial pulsation of the Be star. We also reassess the HMCV classification based on properties of known Be star-white dwarf systems.

arXiv commentAccepted for publication in the Astrophysical Journal