Analysis of TESS observations of V844 Her during the 2020 superoutburst

TL;DR

This study analyzes TESS data of V844 Her's 2020 superoutburst, confirming superhump stages and providing insights into superhump period behavior, with implications for understanding dwarf nova phenomena.

Contribution

It offers a detailed analysis of superhump stages in V844 Her using satellite data, highlighting the period evolution and post-outburst behavior, which is novel in the context of TESS observations.

Findings

Confirmed superhump stages A, B, and C in V844 Her.

Detected superhumps for 18 days post-superoutburst with stable period.

Identified small wiggles possibly related to similar phenomena in other stars.

Abstract

I analyzed Transiting Exoplanet Survey Satellite (TESS) observations of the 2020 superoutburst of the SU~UMa-type dwarf nova V844 Her. This object showed "textbook" superhump stages A, B and C confirmed by modern satellite observations. The resultant figure can be used for an illustration of the concept of superhump stages under the Creative Commons (CC-BY-NC) licence. During the growing phase of superhumps, the period was initially close to, but slightly longer than the orbital period. Observers should pay attention to the presence of such a phenomenon not to confuse the phenomenon with early superhumps seen in WZ Sge stars. After the superoutburst, superhumps were detected for additional 18 d with the same period and no orbital signal was detected. Small wiggles with a period of ~0.5 d were recorded in the post-superoutburst phase and they may be the same phenomenon recorded in the Kepler data of the SU UMa star V585 Lyr.