Simultaneous Multiwavelength Flare Observations of EV Lacertae

We present the first results of our ongoing project conducting simultaneous multiwavelength observations of flares on nearby active M dwarfs. We acquired data of the nearby dM3.5e star EV Lac using five different observatories: NASA's Transiting Exoplanet Survey Satellite (TESS), NASA's Neil Gehrels Swift Observatory (Swift), NASA's Neutron Interior Composition Explorer (NICER), the University of Hawaii 2.2-meter telescope (UH88), and the Las Cumbres Observatory Global Telescope (LCOGT) Network. During the similar to 25 days of TESS observations, we acquired three simultaneous UV/X-ray observations using Swift that total similar to 18 ks, 21 simultaneous epochs totaling similar to 98 ks of X-ray data using NICER, one observation (similar to 3 hr) with UH88, and one observation (similar to 3 hr) with LCOGT. We identified 56 flares in the TESS light curve with estimated energies in the range log E (T) (erg) = (30.5-33.2), nine flares in the Swift UVM2 light curve with estimated energies in the range log E (UV) (erg) = (29.3-31.1), 14 flares in the NICER light curve with estimated minimum energies in the range log E ( N ) (erg) = (30.5-32.3), and 1 flare in the LCOGT light curve with log E ( L ) (erg) = 31.6. We find that the flare frequency distributions (FFDs) of TESS and NICER flares have comparable slopes, beta ( T ) = -0.67 +/- 0.09 and beta ( N ) = - 0.65 +/- 0.19, and the FFD of UVOT flares has a shallower slope (beta ( U ) = -0.38 +/- 0.13). Furthermore, we do not find conclusive evidence for either the first ionization potential (FIP) or the inverse FIP effect during coronal flares on EV Lac.

Automated summary

This study presents the initial results of simultaneous multiwavelength observations of flares on nearby active M dwarfs, where data from various observatories were used to obtain a comprehensive understanding of flare activity. The frequency distribution of flares observed by TESS and NICER showed similar slopes, while the UVOT flares had a shallower slope in comparison. Additionally, no conclusive evidence for the first ionization potential (FIP) or the inverse FIP effect during coronal flares on EV Lac was found.