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Connecting M Dwarf Pulsation and Surface Activity for Gap Stars

Presentation #305.12 in the session Stars, Cool Dwarfs, Brown Dwarfs — iPoster Session.

Published onJun 29, 2022
Connecting M Dwarf Pulsation and Surface Activity for Gap Stars

The main sequence gap in the M dwarf regime reported in Jao et al. (2018) is a result of 3He mixing during the merger of envelope and core convection zones. Models indicate that stars in a narrow mass range around 0.3 M will exhibit instability phases during which their dynamos can switch between the alpha-omega dynamo, like that of the Sun, and the omega-squared dynamo seen in fully convective M dwarfs. Consequently, these red dwarfs undergo slow radial pulsations that last millions to a billion of years. This causes their luminosities and radii to fluctuate, much like the pulsations observed in evolved stars like red giants and those on the asymptotic giant branch. Thus, these stars form a unique class of dwarf like no other on the main sequence. In this work, we present photometric results from TESS and ground-based spectroscopic observations to determine if the unstable interior structures of these stars result in observable characteristics such as high flare rates, fast rotation, or H-alpha emission. This effort has been supported by the NASA’s ADAP program through grant 80NSSC21K2004 , and NASA’s NN-EXPLORE Program using the CHIRON spectrograph on the SMARTS 1.5m at CTIO.

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