Stellar flares with Ariel: detection prospects and impacts on exoplanet spectroscopy
Abstract
Stellar flares are important tracers of magnetic activity and can significantly influence the characterization of exoplanet host stars by introducing time-dependent astrophysical variability. ESA's Ariel mission, designed for atmospheric characterization of exoplanets, will include the VISPhot instrument, providing high-cadence optical photometry offering an opportunity to study stellar flares while identifying and mitigating their impact on transit spectroscopy. We discuss Ariel's potential for flare studies, emphasizing the importance of short-cadence observations for resolving flare morphology and estimating flare energies. We identify potential flaring targets within the Ariel Mission Candidate Sample by cross-matching it with a TESS-based flare catalog, identifying 44 stars in the sample of 3321 host stars with flare rates spanning 0.0012-1.05 flares per day yielding a lower limit. The majority of these active stars are expected to flare infrequently during typical Ariel observations, but for a few of the most active targets there is a significant chance of flaring during a typical Ariel observing window. We further investigate the detectability of stellar flares in Ariel's wavelength range using synthetic spectra based on time-dependent RADYN flare models propagated through the Ariel radiometric simulator. Our simulations indicate that strong flares on cool dwarfs can produce measurable infrared signatures, with flux variations reaching several percent, substantially exceeding the amplitudes of typical exoplanet atmospheric features. These results demonstrate stellar flares represent both a valuable ancillary science case and a potential source of contamination for Ariel observations, highlighting the need for improved flare models and mitigation strategies to maximize the mission's scientific return.
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BibTeX
@misc{vida2026stellar,
title = {{Stellar flares with Ariel: detection prospects and impacts on exoplanet spectroscopy}},
author = {K. Vida and B. Seli and B. Edwards},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.28001},
eprint = {2609.28001},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.28001},
}
RIS
TY - UNPB
TI - Stellar flares with Ariel: detection prospects and impacts on exoplanet spectroscopy
AU - K. Vida
AU - B. Seli
AU - B. Edwards
PY - 2026
DA - 2026/09/23
PB - arXiv
DO - 10.48550/arxiv.2609.28001
UR - https://arxiv.org/abs/2609.28001
AB - Stellar flares are important tracers of magnetic activity and can significantly influence the characterization of exoplanet host stars by introducing time-dependent astrophysical variability. ESA's Ariel mission, designed for atmospheric characterization of exoplanets, will include the VISPhot instrument, providing high-cadence optical photometry offering an opportunity to study stellar flares while identifying and mitigating their impact on transit spectroscopy. We discuss Ariel's potential for flare studies, emphasizing the importance of short-cadence observations for resolving flare morphology and estimating flare energies. We identify potential flaring targets within the Ariel Mission Candidate Sample by cross-matching it with a TESS-based flare catalog, identifying 44 stars in the sample of 3321 host stars with flare rates spanning 0.0012-1.05 flares per day yielding a lower limit. The majority of these active stars are expected to flare infrequently during typical Ariel observations, but for a few of the most active targets there is a significant chance of flaring during a typical Ariel observing window. We further investigate the detectability of stellar flares in Ariel's wavelength range using synthetic spectra based on time-dependent RADYN flare models propagated through the Ariel radiometric simulator. Our simulations indicate that strong flares on cool dwarfs can produce measurable infrared signatures, with flux variations reaching several percent, substantially exceeding the amplitudes of typical exoplanet atmospheric features. These results demonstrate stellar flares represent both a valuable ancillary science case and a potential source of contamination for Ariel observations, highlighting the need for improved flare models and mitigation strategies to maximize the mission's scientific return.
ER -