Space Weather & Heliophysics

Identifying Flare Locations Through Exoplanet Transit Occultations

By Keith Cowing

Status Report

astro-ph.EP

January 11, 2025

Filed under astro-ph.EP, atmospheric erosion, atmospheric escape, CM Draconis, coronal mass ejection, eclipsing binary, habitability, Habitable Zone, heliophysics, high-energy particle, M Dwarfs, photometry, space weather, Stellar Cartography, TESS

Identifying Flare Locations Through Exoplanet Transit Occultations — Top row: 125 flares discovered in CM Draconis, stacked together and aligned to have a peak at 𝑡 = 0. The candidate occulted flare is highlighted in red. Flares occurring during the eclipse but likely not occulted are in blue. All other flares are in grey. The two top plots show the same information, but the top right is zoomed in on the occulted flare candidate, which is seen to drop in flux quicker than almost every other flare. Bottom row: flare amplitude 10 minutes after peak as a function of the flare amplitude at its peak. The bottom right plot is zoomed on the blue square parameter space. Color-coding is the same as the top plots. Higher-amplitude flares tend to decay over a longer time, hence there is generally a positive correlation between the peak and 10-minute amplitude. However, for a given peak amplitude there is a significant spread in how long the decay takes. The candidate occulted flare definitely had a rapid decay, but it is not a large outlier. — astro-ph.EP

M dwarfs are the most common stars in the galaxy, with long lifespans, a high occurrence rate of rocky planets, and close-in habitable zones.

However, high stellar activity in the form of frequent flaring and any associated coronal mass ejections may drive atmospheric escape with the bombardment of radiation and high-energy particles, drastically impacting the habitability of these systems.

The stellar latitude where flares and coronal mass ejections occur determines the space weather that exoplanets are subject to, with high-energy particle events associated with equatorial flares producing significant atmospheric erosion.

However, the flaring latitudes for M dwarfs remain largely unconstrained. To aid in the effort to locate these flaring regions we explore the applicability of flare occultations using optical photometry to identify the latitudes of flares.

As a planet transits in front of an ongoing flare the timing and geometry of the transit can be used to constrain the latitude and longitude of the flare. We predict the probability of detecting an occultation for known transiting planets and eclipsing binaries.

From this, we estimate 3-22 detectable occultations exist within the TESS primary mission photometry, with the majority occurring in eclipsing binary observations. To demonstrate this technique, we analyze a candidate flare occultation event for the eclipsing binary CM Draconis.

Tayt Armitage, David V. Martin, Romy Rodríguez Martínez

Comments: Under review at MNRAS updated in regards to third referee report. 16 pages. 12 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2501.04866 [astro-ph.EP] (or arXiv:2501.04866v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2501.04866
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Submission history
From: Tayt Armitage
[v1] Wed, 8 Jan 2025 22:32:42 UTC (3,349 KB)
https://arxiv.org/abs/2501.04866
Astrobiology,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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