Tilted discs in six poorly studied cataclysmic variables

TL;DR

This study identifies negative superhumps in six poorly studied cataclysmic variables using TESS data, providing new insights into their orbital dynamics and system parameters.

Contribution

We discovered negative superhumps in six cataclysmic variables and proposed an improved mass ratio - superhump deficit relation based on our findings.

Findings

Detected negative superhumps in six systems.

Estimated mass ratios and orbital inclinations for these systems.

Identified systems as prime targets for follow-up spectroscopy.

Abstract

In this work, we search for negative superhumps (nSHs) in poorly studied cataclysmic variables using TESS data. We find three eclipsing binaries with nSH signatures: HBHA 4204-09, Gaia DR3 5931071148325476992, and SDSS J090113.51+144704.6. The last one exhibits IW And-like behaviour in archival ZTF data, and appears to have shallow, grazing eclipses. In addition, we detect nSH signatures in two non-eclipsing systems: KQ Mon and Gaia DR3 4684361817175293440, by identifying the orbital period from the superorbital-dependent irradiation of the secondary. We discover nSH signatures in one more system, [PK2008] HalphaJ103959, by using an orbital period from another work. An improved mass ratio - nSH deficit relation $q(\varepsilon_-)$ is suggested by us, which agrees with independent measurements on nova-like variables. With this relation, we estimate the mass ratios of all systems in our sample, and determine the orbital inclinations for the three that are eclipsing. All systems with discovered nSHs in this work are excellent targets for follow-up spectroscopic studies.