The Flaring TESS Objects of Interest: Flare Rates for all Two Minute Cadence TESS Planet Candidates

Abstract

Although more than 5000 TESS Objects of Interest have been cataloged, no comprehensive survey of the flare rates of their host stars exists. We perform the first flare survey of all 2250 non-retired TOIs with 2 min cadence light curves to measure or place upper limits on their flare rates. We find 93 candidates orbit flare stars and measure their flare frequency distributions. Across the sample, TOIs of ≤1.5𝑅 ⊕ orbit flare stars more frequently than do TOIs of 1.5<R<2.75𝑅 ⊕ , 2.75<R<4𝑅 ⊕ , or R≥4𝑅 ⊕ . We sort all TOI host stars by their flare rate/upper limit, stellar mass, and distance to create a flare ranking metric (FRM) to determine suitability for follow-up. The FRM of each TOI is then checked against the expected signal-to-noise of atmospheric features in transmission spectroscopy to locate the most promising targets. We find 1/4 of terrestrial M-dwarf planets amenable to transmission spectroscopy orbit flare stars. However, none of the M-dwarf hosts to terrestrial planets are currently flaring at sufficient levels for >99.9% atmospheric ozone depletion. We give the first upper limits on the flare rate of the host star to TOI 700 d and explore the flare rates incident on young planets such as DS Tuc Ab.

Sporadic Spin-orbit Variations in Compact Multiplanet Systems and Their Influence on Exoplanet Climate

“…In addition to climatic influences, those related to photochemistry and the formation of clouds and hazes may be markedly different if alternating regions of the planet are exposed to the star. For instance, the impact of stellar UV flare events (Howard 2022;Paudel et al 2021;Louca et al 2022) and stellar plasma (e.g., protons and α-particles; Chen et al 2021a) on varying sides of the hemisphere may lead to different global chemical and participle precipitation rates. Moreover, distinct atmospheric dynamics due to oscillating planetary spin (Figure 5) could drive the planet into other transport regimes (Carone et al 2018;Chen et al 2019) and change how chemical species and aerosols are advected from the dayside to the nightside (Boutle et al 2020;Cohen et al 2021).…”