2024ApJ...965...56B -
Astrophys. J., 965, 56 (2024/April-2)
Correlations between Ca II H and K Emission and the Gaia M Dwarf Gap.
BOUDREAUX E.M., GARCIA SOTO A. and CHABOYER B.C.
Abstract (from CDS):
The Gaia M dwarf gap, also known as the Jao Gap, is a novel feature discovered in the Gaia Data Release 2 G versus BP-RP color-magnitude diagram. This gap represents a 17% decrease in stellar density in a thin magnitude band around the convective transition mass (∼0.35 M⊙) on the main sequence. Previous work has demonstrated a paucity of Hα emission coincident with the G magnitude of the Jao Gap in the solar neighborhood. The exact mechanism that results in this paucity is as of yet unknown; however, the authors of the originating paper suggest that it may be the result of complex variations to a star's magnetic topology driven by the Jao Gap's characteristic formation and breakdown of stars' radiative transition zones. We present a follow-up investigating another widely used magnetic activity metric, Calcium II H and K emission. Ca II H and K activity appears to share a similar anomalous behavior as Hα does near the Jao Gap magnitude. We observe an increase in star-to-star variation of magnetic activity near the Jao Gap. We present a toy model of a star's magnetic field evolution, which demonstrates that this increase may be due to stochastic disruptions to the magnetic field originating from the periodic-mixing events characteristic of the convective kissing instabilities that drive the formation of the Jao Gap.
Abstract Copyright:
© 2024. The Author(s). Published by the American Astronomical Society.
Journal keyword(s):
Stellar evolution - Stellar evolutionary models
Status at CDS
:
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Simbad objects:
183
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