Fig11_2Formation_of_a_plantary_nebula_and_white_dwarf_star.jpg

Fig11_2Formation_of_a_plantary_nebula_and_white_dwarf_star.jpg

Fig. 11.2 . The evolutionary track of a dying Sun-like star in the Hertzsprung-Russell diagram. When the star has used up its nuclear hydrogen fuel, which makes the star shine, it expands into a red giant star, and after a relatively short time the giant star ejects its outer layers to form a planetary nebula. The ejected gas exposes a hot stellar core, which collapses to form an Earth-sized white dwarf star that gradually cools into dark invisibility. The luminosity is in units of the Sunís luminosity, denoted L?, and the effective temperature of the stellar disk is in units of degrees kelvin, designated K.

Copyright 2010, Professor Kenneth R. Lang, Tufts University