TESS Duotransit Candidates from the Southern Ecliptic Hemisphere

TL;DR

This paper reports the discovery of 85 long-period exoplanet candidates from TESS data in the Southern Ecliptic Hemisphere, including 60 new candidates identified through duotransit events, aiding the study of solar system-like planets.

Contribution

The study introduces a novel method for identifying long-period exoplanets via duotransits in TESS data, expanding the catalog of potential solar system analogs.

Findings

85 duotransit candidates identified

60 are new candidates

Candidates have periods typically over 20 days

Abstract

Discovering transiting exoplanets with long orbital periods allows us to study warm and cool planetary systems with temperatures similar to the planets in our own Solar system. The TESS mission has photometrically surveyed the entire Southern Ecliptic Hemisphere in Cycle 1 (August 2018 - July 2019), Cycle 3 (July 2020 - June 2021) and Cycle 5 (September 2022 - September 2023). We use the observations from Cycle 1 and Cycle 3 to search for exoplanet systems that show a single transit event in each year - which we call duotransits. The periods of these planet candidates are typically in excess of 20 days, with the lower limit determined by the duration of individual TESS observations. We find 85 duotransit candidates, which span a range of host star brightnesses between 8 < $T_{mag}$ < 14, transit depths between 0.1 per cent and 1.8 per cent, and transit durations between 2 and 10 hours with the upper limit determined by our normalisation function. Of these candidates, 25 are already known, and 60 are new. We present these candidates along with the status of photometric and spectroscopic follow-up.