Humanity has made astonishing progress in exoplanet discovery over the past three decades: Approximately 4,000 exoplanets are now known within our Galaxy. The vast majority of these planets orbit single stars; even so, almost 100 binary star systems have been found to possess planets. Planets in binary systems have been difficult to detect for a number of reasons, such as dilution of a transiting planet's signal by the companion star, or observational bias as many surveys focus on finding planets orbiting single stars. Estimates indicate most stars exist in binary or multiple systems, and in particular a large fraction of cooler stars exist in such configurations, making the search for circumbinary planets a compelling subject for exploration. Although planet transits are challenging to detect in binary systems, the presence of the companion star allows the use of another method for planet detection: Eclipse timing variations (ETVs), referring to the small variations in the time it takes for one star to eclipse the other. ETVs can be caused by an unseen third body in a binary system perturbing the orbits of its host stars, such that potential circumbinary planets can be detected by searching for periodic ETVs. Continuous everyday coverage is ideal for measuring eclipse times accurately, and multi-year observations are necessary to provide enough eclipses that potentially habitable, long-period planet candidates can be identified. To date, just nine planets have been discovered using ETVs, so there is much work to be done in this largely untapped parameter space. The Evryscope, deployed to CTIO in 2016, consists of two dozen small telescopes housed in a single dome, arranged for coverage of the entire visible sky. With its multi-year data set, its time precision, and its sky coverage, the Evryscope is uniquely suited for an all-sky survey in search of long-period planet candidates using the method of ETVs. In this work, we present initial findings and discoveries from the beginnings of the Evryscope ETV survey.
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020