Single Transit Candidates from K2: Detection and Period Estimation

TL;DR

This paper introduces a Bayesian transit-fitting method to analyze single transit events in photometric surveys, enabling the estimation of exoplanet orbital periods and radii from limited data.

Contribution

The paper develops and tests a novel Bayesian MCMC tool for extracting orbital parameters from single transit signals in K2 data, expanding detection capabilities.

Findings

Successfully identified a promising exoplanet candidate with a ~540-day period.

Detected six additional transit candidates requiring follow-up.

Demonstrated the method's potential for future surveys like TESS and PLATO.

Abstract

Photometric surveys such as Kepler have the precision to identify exoplanet and eclipsing binary candidates from only a single transit. K2, with its 75d campaign duration, is ideally suited to detect significant numbers of single-eclipsing objects. Here we develop a Bayesian transit-fitting tool ("Namaste: An Mcmc Analysis of Single Transit Exoplanets") to extract orbital information from single transit events. We achieve favourable results testing this technique on known Kepler planets, and apply the technique to 7 candidates identified from a targeted search of K2 campaigns 1, 2 and 3. We find EPIC203311200 to host an excellent exoplanet candidate with a period, assuming zero eccentricity, of $540 ^{+410}_{-230}$ days and a radius of $0.51 \pm 0.05 R_{Jup}$. We also find six further transit candidates for which more follow-up is required to determine a planetary origin. Such a technique could be used in the future with TESS, PLATO and ground-based photometric surveys such as NGTS, potentially allowing the detection of planets in reach of confirmation by Gaia.