Z Cam star PY Per in SU UMa state?

TL;DR

This study reclassifies PY Per as a Z Cam + VY Scl star, revealing complex outburst behaviors including superoutbursts, and highlights its long orbital period which is unusual for such phenomena.

Contribution

It provides new observational evidence of superoutbursts in a long orbital period system, challenging existing classifications and understanding of dwarf novae.

Findings

PY Per exhibits faint states characteristic of VY Scl stars.

The 2021-2022 outburst resembled a superoutburst with a long plateau.

The system has a long orbital period of approximately 0.155 days.

Abstract

PY Per has been known as a Z Cam star. Using VSOLJ, VSNET, AAVSO, ASAS-SN and ZTF observations, I found that this object experienced faint states and classified it to be a Z Cam + VY Scl star. Furthermore, the object changed the outburst behavior since 2020 and it has been showing regularly recurring long, bright outbursts with cycles of 110-160 d and short, faint outbursts between them. The 2021 December--2022 January outburst particularly resembled a superoutburst with a gradually fading plateau phase having a duration more than 25 d and two rebrightenings in the fading part. This object has a long orbital period of 0.15468(5) d based on the TESS data and the previous radial-velocity study. The existence of a superoutburst in a system with a long orbital period would be unusual, but not unprecedented. Since the phenomenon may still be ongoing, I draw attention to this object when it emerges from in the morning sky after the solar conjunction.