what is at the center of a planetary nebula
Planetary nebula A mechanism for formation of most planetary nebulae is thought to be the following: at the end of the star's life, during the red-giant phase, the outer layers of the star are expelled by strong stellar winds. After most of the red giant's atmosphere is dissipated, the ultraviolet radiation of the hot luminous core, called a planetary nebula nucleus (PNN), ionizes the outer layers earlier ejected from the star.[2] Absorbed ultraviolet light energises the shell of nebulous gas around the central star, causing it to appear as a brightly coloured planetary nebula.
My Ántonia
Van der Waals equation is the volume of the container occupied by each particle (not the velocity of a particle), and k is the Boltzmann constant. It introduces two new parameters: a', a measure of the average attraction between particles, and b', the volume excluded from v by one particle.
Gilbert Gottfried In March 2011, Gottfried made a series of jokes on his Twitter account about the