Hertzsprung-Russell diagram of the stellar XMMSL2 sources with known parallax,the color scales with the logarithmic X-ray luminosity log(L _x). The red dashed line represents the theoretical main sequence following Pecaut & Mamajek (2013), and the dotted lines show the assumed width of the main sequence. The star marker represents the position of the Sun; we note that the Sun is less luminous than the stellar XMMSL2 sources. The density of the distribution is indicated by the colored lines. The ranges of the spectral types for dwarfs are given at the bottom of the figure.