HS Hya about to turn off its eclipses

TL;DR

This study presents the first long-term analysis of HS Hya, revealing a rapid inclination change causing the eclipses to nearly disappear, driven by a third component inducing orbital precession, emphasizing the need for urgent new observations.

Contribution

It provides the first detailed long-term analysis of HS Hya's inclination evolution and its effects on eclipse visibility, highlighting the role of a third component in orbital precession.

Findings

Inclination changed by over 15 degrees since discovery

Eclipses are now almost undetectable

Precession period of about 631 years

Abstract

Aims: We aim to perform the first long-term analysis of the system HS Hya. Methods: We performed an analysis of the long-term evolution of the light curves of the detached eclipsing system HS Hya. Collecting all available photometric data since its discovery, the light curves were analyzed with a special focus on the evolution of system's inclination. Results: We find that the system undergoes a rapid change of inclination. Since its discovery until today the system's inclination changed by more than 15 deg. The shape of the light curve changes, and now the eclipses are almost undetectable. The third distant component of the system is causing the precession of the close orbit, and the nodal period is about 631 yr. Conclusions: New precise observations are desperately needed, preferably this year, because the amplitude of variations is decreasing rapidly every year. We know only 10 such systems on the whole sky at present.