Eclipse timing variation (ETV) analysis of short period binaries is a useful method to detect circumbinary exoplanets. ETV method relies on precise photometric observations that span over decades to sample enough the light-time effect due to the presence of exoplanets. Like many exoplanet detection methods, ETV studies have its own selection bias. The shorter the orbital period of the binary, the more precise photometric observation become possible, which produces more data to think/talk about. As a result, recent ETV studies pointed their interests in a binary type with a very short orbital period, so called HW Vir-type binaries. Recent ETV studies about HW Vir-type eclipsing binaries, proposed circumbinary planets around a significant percent of these rare systems. While many of them are doubtful, the results raised questions about the origins of the planets as well as the origin of the binaries.
In this seminar, I will talk about ETV method, HW Vir-type binaries and results of recent ETV analyzes of such systems.