Hidden Transits: TOI-2285 b is a Warmer sub-Neptune Likely with a Super-Earth Companion

TL;DR

This paper corrects the orbital period of TOI-2285 b, revealing it is warmer than previously thought, and reports a new planetary candidate, emphasizing the importance of thorough data analysis in exoplanet discovery.

Contribution

It provides a revised orbital period for TOI-2285 b and identifies a new planetary candidate, demonstrating the significance of harmonic analysis in transit data interpretation.

Findings

TOI-2285 b's true period is 13.64 days, not 27.27 days.

The equilibrium temperature of TOI-2285 b is 358 K.

A new planetary candidate with a 9.67-day period was identified.

Abstract

TOI-2285 b is a sub-Neptune-sized planet orbiting a nearby M dwarf, discovered through the TESS photometric survey and ground-based follow-up observations. The planet was initially reported to have an orbital period of 27.27 d, making it one of the lowest temperature sub-Neptunes transiting a bright M dwarf. However, additional TESS data reveal that its true orbital period is 13.64 d, half the original value, resulting in a warmer equilibrium temperature (358 K) than previously estimated (284 K). The misidentification likely resulted from the low signal-to-noise ratio of individual transit signals and the limited number of transits observed by TESS at that time. This case highlights the importance of carefully considering harmonic solutions for similar cases. The additional TESS data also reveal another planetary candidate with an orbital period of 9.67 d and a radius of 1.5 $R_\oplus$, requiring validation in future studies.