http://arxiv.org/abs/1806.07792
We present the discovery of a gap near $M_{G}\approx$10 in the main sequence on the Hertzsprung-Russell Diagram (HRD) based on measurements presented in Gaia Data Release 2 (DR2). Using an observational form of the HRD with $M_{G}$ representing luminosity and $G_{BP}-G_{RP}$ representing temperature, the gap presents a diagonal feature that dips toward lower luminosities at redder colors. The gap is seen in samples extracted from DR2 with various distances, and is not unique to the {\it Gaia} photometry — it also appears when using near-IR photometry ($J-K_{s}$ vs $M_{K_{s}}$). The gap is very narrow ($\sim$0.05 mag) and is near the luminosity-temperature regime where M dwarf stars transition from partially to fully convective, i.e., near spectral type M3.0V. This gap provides a new feature in the H-R Diagram that hints at an underlying astrophysical cause and we propose that it is linked to the onset of full convection in M dwarfs.
W. Jao, T. Henry, D. Gies, et. al.
Thu, 21 Jun 18
32/46
Comments: 12 pages, 10 figures and accepted for publication in ApJL
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