In this study, we investigate the intriguing optical variability and magnetic activity exhibited by young M-dwarfs including brown dwarfs (BD). By analyzing Indian ground-based telescope data and space-based TESS satellite data, we identify and characterize significant fluctuations in their brightness, providing new insights into the nature of variability. We modelled the star surface to uncover any spot dynamics and its correlation with magnetic activities, i.e., flares. We detected both simple and complex flare events in both M-dwarfs and brown dwarfs with energies ranging from ~10^32 to 10^36 ergs. We estimated the flare frequency distribution and correlated the flare energies with flare duration and bolometric luminosity.

For an active M4.5 dwarf AD Leonis, we examine its magnetic activity through a combined analysis of TESS photometric data and optical spectroscopic observations. Interestingly, we correlate the long-term magnetic activity cycle of AD Leo with the flare event rate. By characterizing the properties of the observed flares and their relation to the star’s magnetic field, we could uncover critical mechanisms behind flare generation and starspot evolution.

In an ongoing project, we are revisiting the spot migration and sun-like flip-flop cycles in a sun-like star AB Dor with TESS data. AB Dor is an ultrafast rotator and highly active star which exhibits both short-term variability (STV), lasting minutes to days, typically due to flaring activity and rotational modulation, and long-term variability (LTV), spanning years to decades, linked to stellar activity cycles. I will present the preliminary results of our analysis on AB Dor.