A growth of early superhump: Multi color observation of the WZ Sge star TCP J23580961+5502508

Abstract

We report optical and near-infrared photometry of a WZ Sge-type dwarf nova, TCP J23580961+5502508, during its 2022 superoutburst, obtained using the 1.5-m Kanata telescope. Our observation detected early superhumps on three consecutive nights which included the rising phase toward the peak of the outburst. The early superhumps exhibited a profile dominated by the primary maximum during the first two days, while a prominent secondary minimum appeared on the third day. We reconstructed the structure of the accretion disk from multi-color light curves using the early superhump mapping. The accretion disk has a prominent flaring structure on the leading side of the disk during the first two days. An additional flaring structure emerged on the opposite side on the third day, forming a two-armed pattern that can be interpreted within the framework of the 2:1 resonance model. The reconstructed disk structure in the first two days suggests the presence of an additional mechanism operating during the initial stage of early superhump development.