Rotational variation in the chemically peculiar B0 star θ Car as seen by TESS

theta Car is a bright well studied B0 type star in a close binary (P-orb = 2.2 d) with an unseen companion. The system has enjoyed extensive spectroscopic characterization at multiple wavelengths, revealing narrow X-ray lines, a soft X-ray tail, and chemical peculiarities. The star was recently observed in high-cadence photometric time-series by the NASA TESS satellite. In this paper, we investigate the photometric variability and demonstrate that it is likely associated with surface brightness inhomogeneities rather than orbital modulation. We investigate the potential distribution of surface features required to produce the observed variability, and report a new rotational period of P-rot = 2.2034 d to be commensurate with the orbital period.

Automated summary

Theta Car is a bright and well-studied B0 type star in a close binary system with an unseen companion, which has been extensively characterized at multiple wavelengths. Recent observations using the NASA TESS satellite show that the photometric variability of the star may be associated with surface brightness inhomogeneities.