A New IW And-Type Star: Karachurin 12 with Tilted Disks and Diverse cycles

TL;DR

This paper reports the discovery of Karachurin 12 as a new IW And-type star with tilted, precessing disks and diverse cycle behaviors, providing new insights into the complex phenomena of cataclysmic variables.

Contribution

It introduces Karachurin 12 as a novel non-eclipsing IW And-type object with tilted disks and detailed cycle analysis, challenging existing models of the phenomenon.

Findings

Karachurin 12 has a 35.69-day cycle period.

It exhibits negative superhumps with a 0.29799-day period.

The NSH amplitude varies throughout the cycle.

Abstract

The IW And-type phenomenon in cataclysmic variables presents a significant challenge to the accretion disk instability model. Using photometric data from the All-Sky Automated Survey for Supernovae, the Zwicky Transient Facility, and the Transiting Exoplanet Survey Satellite, we identify Karachurin 12 as a new non-eclipsing IW And-type object with a cycle period of 35.69(3) days. We also report for the first time that Karachurin 12 is a negative superhump (NSH) system featuring a precessing tilted disks, with precession, orbital, and NSH periods of 4.9588(2) days, 0.3168895(13) days, and 0.2979861(8) days, respectively. Our analysis, using dips as index and NSHs as probe, reveals diverse cycle patterns in Karachurin 12, with NSH amplitude varying throughout the cycle. These findings offer new insights for studying tilted disks and the IW And-type phenomenon. The mass-transfer burst model has difficulty explaining the observed variations in NSH amplitude, especially given the uncertainty surrounding the origin of the mass transfer burst. Meanwhile, the tilted thermally unstable disk model indicates a possible connection to the IW And-type phenomenon, but it also struggles to account for the detailed variations in Karachurin 12. Therefore, a wider range of factors must be considered to fully understand the complex changes in Karachurin 12.