Characteristics of the Permanent Superhumps in V533 Herculis

TL;DR

This study analyzes TESS data of V533 Her, revealing the orbital period and positive superhumps, and explores the relationship between superhump amplitude and disk precession rate, providing insights into accretion disk dynamics.

Contribution

It presents the first detailed analysis of superhumps in V533 Her using TESS data, including revised orbital period and superhump characteristics.

Findings

Revised orbital period: 3.53709(2) hours.

Detected positive superhumps with periods near 3.8 hours.

Found correlation between superhump amplitude and disk precession rate.

Abstract

We analyze two sectors of TESS photometry of the nova-like cataclysmic variable star V533 Her. We detect a periodicity consistent with the binary orbital period and estimate a revised value of 3.53709(2) hr. We also detect a strong signal near a period of 3.8 h that we associate with positive superhumps. The superhump frequency varies over the TESS observations with the fractional difference between the superhump and orbital periods, $\epsilon$, ranging between $0.055\le \epsilon \le 0.080$. The superhump amplitude is correlated with its frequency such that the amplitude increases as $\epsilon$ decreases. Positive superhumps result from an instability that generates an eccentric accretion disk and $\epsilon$ is a measure of the disk precession rate in the binary rest frame. The observed correlation implies that as the disk precession rate slows, the disk eccentricity increases.