(when the centripetal acceleration exceeds the local acceleration of gravity). Its centripetal acceleration is so great that the The surface speed is greater than 1/10th the Pulsars spin at periods rangingįrom 4 s to 1.6 ms. Stars with very high magnetic fields, tilted with respect to the spin axis. It is hard to visualize how great the compression is from the white-dwarf-sized core to a neutron star. Have smaller radii, up to ~ 3 solar masses. Is a neutron degenerate gas, with same temperature-independent pressureĪs for electron degeneracy. so the protons and electronsĪre combined to form neutrons-a neutron star. Systems, due to enhancement as star collapses (conservation of magneticįlux, as we saw during the collapse of protostars).Įlectron degeneracy is no longer enough to keep gravity at bay, and matter T are seen in a few percent of white dwarfs, especially those in binary ~ 0.03% compared to theoretically exact value 0.028%. Where doppler shifts are accurately known. Order to test this prediction observationally we must use binary systems This shift is in addition to any doppler shifts caused by motions, so in This is equivalent to a "red shift"Īnd is called the gravitational redshift. Photons lose energyīy going to longer wavelengths. But photons have to travelĪt the speed of light - they can never slow down. Like throwing a ball into theĪir causes the ball to lose kinetic energy (changing it into potentialĮnergy), so too, photons lose energy. Lecture that photons lose energy in "climbing out of" a gravitational well Of the radius of the Sun, or about the size of the Earth. The constant radius line in the H-R diagram.Īnd a temperature of T ~ 29,000 K. They neverĬhange size once they become a white dwarf, so as they cool they follow Since white dwarfs have no nuclear engine, they cool off over severalīillion years, until they become a black dwarf. More massive a white dwarf, the smaller its radius. Inside the star does not depend on temperature, in contrast to ordinary Planetary nebula => the "bare core" becomes a white dwarf).ĭegenerate matter (all available electron energy states are filled, nucleiĪre in tightly packed "crystalline-lattice-like" state), with a very thinĪtmosphere of non-degenerate matter over the surface.