Astrophysical applications of stellar trigonometric parallaxes.

Accurate stellar trigonometric parallaxes may provide reliable data for studies on the physical properties and evolutional status of stars such as white dwarfs, red dwarfs, O and B stars, Herbig Ae and Be stars, and Ap and Am stars. Some fundamental parameters like absolute magnitude, effective temperature and radii of these stars and their positions in the HR diagram are of great importance in astronomical researches.