E5 - Nuclear fusion and the stars

why are stable stars in equilibrium?

balance of the inward gravitational pressure and the outward radiation pressure

main sequence star

fuses hydrogen into helium

red giant

bright, large, cool, reddish, tenuous

super red giant

even larger and brighter than red giants

white dwarf

dim, small, hot, whitish, dense

neutron star

dimmer and smaller than a white dwarf with a density similar to that of nuclei. Too dim to show on an HR diagram

black hole

the end point of the very massive stars

The Oppenheimer-Volkoff limit

the largest mass a neutron star can have, equal to about 3M_⊙

instability region

the delicate balance between radiation and gravitational pressures has been disturbed, the star tries to find a new equalibrium but instead the star pulsates, it grows and shrinks in size. This makes luminosity variable in this region