ASASSN-14ho: Longest-period Dwarf Nova with Multiple Rebrightenings

TL;DR

This paper reports the discovery of multiple rebrightenings in the long-period dwarf nova ASASSN-14ho, challenging existing theories that associate rebrightenings mainly with short-period systems, and suggests it may be an SU UMa-type near the 3:1 resonance.

Contribution

It presents the first observation of multiple rebrightenings in a long-period dwarf nova and discusses its potential classification as an SU UMa-type near the 3:1 resonance.

Findings

Four post-outburst rebrightenings observed in ASASSN-14ho

ASASSN-14ho has an exceptionally long orbital period of 0.24315 days

Possible classification as an SU UMa-type dwarf nova near the 3:1 resonance

Abstract

The post-outburst rebrightening phenomenon in dwarf novae and X-ray novae is still one of the most challenging subjects for theories of accretion disks. It has been widely recognized that post-outburst rebrightenings are a key feature of WZ Sge-type dwarf novae, which predominantly have short ($\lesssim$0.06 d) orbital periods. I found four post-outburst rebrightenings in ASASSN-14ho during its 2014 outburst, whose orbital period has recently measured to be exceptionally long [0.24315(10) d]. Using the formal solution of the radial velocity study in the literature, I discuss the possibility that this object can be an SU UMa-type dwarf nova near the stability border of the 3:1 resonance despite its exceptionally long orbital period. Such objects are considered to be produced if mass transfer occurs after the secondary has undergone significant nuclear evolution and they may be hidden in a significant number among dwarf novae showing multiple post-outburst rebrightenings.