An Estimate of the Yield of Single-Transit Planetary Events from the Transiting Exoplanet Survey Satellite

TL;DR

This paper estimates the number of single-transit exoplanets TESS will detect, highlighting their potential for follow-up studies and the significant increase in long-period planet discoveries, including habitable zone candidates.

Contribution

It provides a semi-analytic prediction of single-transit planet yields from TESS using the CTL-6 catalog, including their characteristics and potential for follow-up.

Findings

Approximately 1,218 single-transit events expected from TESS observations.

Over 90% of these events will have detectable signals for ground-based follow-up.

Including single transits doubles the number of long-period planets detected by TESS.

Abstract

We present a semi-analytic estimate of the expected yield of single-transit planets from the Transiting Exoplanet Survey Satellite (TESS). We use the TESS Candidate Target List 6 (CTL-6) as an input catalog of over 4 million sources. We predict that from the 200,000 stars selected to be observed with the high-cadence postage stamps with the highest CTL-6 priority, there will be 241 single-transit events caused by planets detectable at a signal-to-noise ratio of SNR$\ge7.3$. We find a lower limit of an additional 977 events caused by single-transit planets in the full frame images (FFI); this is a lower limit because the CTL-6 is incomplete below a TESS magnitude of $T>12$. Of the single-transit events from the postage stamps and FFIs, 1091/1218 will have transit depths deeper than 0.1%, and will thus be amenable for photometric follow-up from the ground, and 1195/1218 will have radial velocity signals greater than 1 m/s. We estimate that the periods of 146 single transits will be constrained to better than 10% using the TESS photometry assuming circular orbits. We find that the number of planets detected by TESS in the postage stamps with periods $P>25$ days will be doubled by including single-transiting planets, while the number of planets with $P>250$ days will be increased by an order of magnitude. We predict 79 habitable zone planets from single-transits, with 18 orbiting FGK stars.