09. Gaia’s M-dwarf Gap and the Transition to Fully Convective Interiors

Abstract

Launched in 2013, the Gaia space telescope measured parallax distances to over 1 billion stars. When comparing the brightnesses and colors of stars observed by Gaia, there appears to be a region where the density of red dwarf stars is lower than expected. We explore the structural instabilities that have been theorized to form this region, now called the “Jao Gap”. To do this, we created a synthetic population of red dwarfs to mimic the population of stars in the local solar neighborhood. Our synthetic population displays a gap that qualitatively shares many similarities with the observed gap. Notably how bright the stars are in the gap, its slope, and the locations of overdense regions. These results boost our confidence in the physics of current stellar structure and evolution models and provide the first definitive evidence that low-mass stars become fully convective.