M dwarf flares and their impact on exoplanet habitability

M dwarfs are the most common stars in the Galaxy and show the highest rocky planet occurrence among all spectral types. Some of these planets orbiting M dwarfs are within the Habitable Zone (HZ). In addition, more than 60% of Ms are active, displaying thousands of flares and superflares events. This can be a double-edge sword in regard of exoplanet habitability: on one hand, stellar activity can alter the atmosphere of a planet, with special emphasis on ozone degradation; on the other hand, flares can promote the abiotic synthesis of organic molecules relevant to the origin of life (nucleobases, sugars, carboxylic acids or aminoacids). Interest in understanding how intensity, frequency and duration of stellar activity can impact the habitability of an exoplanet is therefore growing. Recent observations of flares have shown that the flaring flux can be x100 times stronger in UV than in the optical. UV is also preferable to constrain more accurately both the prebiotic abiogenesis and the Ozone depletion. For these reasons, we propose to use a CubeSat to complement current flare surveys operating in the optical. This CubeSat will observe a high number of flaring M dwarfs, following an all-sky scanning law coverage, both in NUV ~[200-275nm] and optical (u’g’r’i’ SDSS) to better compare the differences in flare colors. The cheap cost and fast building of such a CubeSat will allow us to complement the data of bright flares acquired from the ground-based, high-cadence, wide FoV surveys with additional UV data from space. After the first calculations with data from the Flaring TESS Objects of Interest [Howard, W. S. (2022)], we expect to observe ~100 flares/day in the visible and ~10 flares/day in NUV coming from M dwarfs within 36pc, with an SNR>10. Another scientific planned goal will be to conduct few-minutes after-the-flare follow-up time-resolved spectroscopy from the ground in the optical, that will be triggered by the detection of UV flares in space on board of the proposed CubeSat. The evolution of continuum and emission lines until reaching quiescent state would deliver precious information of the flare physics scenario. Finally, the study of M dwarfs stellar activity in the NUV band will provide useful data for larger forthcoming missions that will survey exoplanets, such as ARIEL, PLATO and LUVOIR.