A Gap in the Lower Main Sequence Revealed by Gaia Data Release 2

作者：Jao Wei Chun^*; Henry Todd J; Gies Douglas R; Hambly Nigel C

来源：Astrophysical Journal Letters, 2018, 861(1): L11.

DOI：10.3847/2041-8213/aacdf6

• Hertzsprung-Russell and C-M diagrams
• stars: distances
• stars: late-type

We present the discovery of a gap near M-G approximate to 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 MG 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 Gaia photometry-it also appears when using near-IR (NIR) photometry (J - K-s versus M-Ks). The gap is very narrow (similar to 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 HRD that hints at an underlying astrophysical cause, and we propose that it is linked to the onset of full convection in M dwarfs.

• 出版日期2018-7-1