CaII and H$α$ flaring M dwarfs detected with multi-filter photometry

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Main Authors: Mas-Buitrago, P., Zhang, J. -Y., Solano, E., Martín, E. L.
Format: Preprint
Published: 2025
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author Mas-Buitrago, P.
Zhang, J. -Y.
Solano, E.
Martín, E. L.
author_facet Mas-Buitrago, P.
Zhang, J. -Y.
Solano, E.
Martín, E. L.
contents Understanding and characterising the magnetic activity of M dwarfs is of paramount importance in the search for Earth-like exoplanets orbiting them. Energetic stellar activity phenomena, such as flares or coronal mass ejections, which are common in these stars, are deeply connected with the habitability and atmospheric evolution of the surrounding exoplanets. We present a follow-up of a sample of M dwarfs with strong H$α$ and CaII H and K emission lines identified with J-PLUS photometry in a previous work. We collected low-resolution NOT/ALFOSC and GTC/OSIRIS spectra, measuring the PC3 index for the spectral type determination. We used two-minute-cadence calibrated TESS light curves to identify and characterise multiple flares and to calculate the rotation period of the two active M dwarfs found in our sample. We confirm that the strong emission lines detected in the J-PLUS photometry are caused by transient flaring activity. We find clear evidence of flaring activity and periodic variability for LP 310-34 and LP 259-39, and estimated flare energies in the TESS bandpass between $7.4\times10^{30}$ and $2.2\times10^{33}$ erg for them. We characterised LP 310-34 and LP 259-39 as very rapidly rotating M dwarfs with CaII H and K and H$α$ in emission, and computed a rotation period for LP 259-39 for the first time: $P_{\rm rot}=1.69\pm0.02$ d. This work advocates the approach of exploiting multi-filter photometric surveys to systematically identify flaring M dwarfs, especially to detect episodes of strong CaII H and K line emission, which may have important implications for exoplanetary space weather and habitability studies. Our results reveal that common M dwarfs experience flare events in CaII H and K in addition to well known H$α$ flares.
format Preprint
id arxiv_https___arxiv_org_abs_2503_22525
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle CaII and H$α$ flaring M dwarfs detected with multi-filter photometry
Mas-Buitrago, P.
Zhang, J. -Y.
Solano, E.
Martín, E. L.
Solar and Stellar Astrophysics
Earth and Planetary Astrophysics
Understanding and characterising the magnetic activity of M dwarfs is of paramount importance in the search for Earth-like exoplanets orbiting them. Energetic stellar activity phenomena, such as flares or coronal mass ejections, which are common in these stars, are deeply connected with the habitability and atmospheric evolution of the surrounding exoplanets. We present a follow-up of a sample of M dwarfs with strong H$α$ and CaII H and K emission lines identified with J-PLUS photometry in a previous work. We collected low-resolution NOT/ALFOSC and GTC/OSIRIS spectra, measuring the PC3 index for the spectral type determination. We used two-minute-cadence calibrated TESS light curves to identify and characterise multiple flares and to calculate the rotation period of the two active M dwarfs found in our sample. We confirm that the strong emission lines detected in the J-PLUS photometry are caused by transient flaring activity. We find clear evidence of flaring activity and periodic variability for LP 310-34 and LP 259-39, and estimated flare energies in the TESS bandpass between $7.4\times10^{30}$ and $2.2\times10^{33}$ erg for them. We characterised LP 310-34 and LP 259-39 as very rapidly rotating M dwarfs with CaII H and K and H$α$ in emission, and computed a rotation period for LP 259-39 for the first time: $P_{\rm rot}=1.69\pm0.02$ d. This work advocates the approach of exploiting multi-filter photometric surveys to systematically identify flaring M dwarfs, especially to detect episodes of strong CaII H and K line emission, which may have important implications for exoplanetary space weather and habitability studies. Our results reveal that common M dwarfs experience flare events in CaII H and K in addition to well known H$α$ flares.
title CaII and H$α$ flaring M dwarfs detected with multi-filter photometry
topic Solar and Stellar Astrophysics
Earth and Planetary Astrophysics
url https://arxiv.org/abs/2503.22525