ASTR-1010 Lecture Notes - Lecture 17: Cepheid Variable, Electron Degeneracy Pressure, Planetary Nebula
19 Mar 2017
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Document Summary
Two stars in a binary system can be close enough to transfer mass to one another this changes the life path of the star. Quantum mechanics: two particles cannot occupy the same space with the same energy. Dead stars (cid:894)neutron stars and white dwarfs(cid:895) are help up through : degeneracy pressure, for very dense solids, electrons cannot be in their ground states they become very energetic, approaching the speed of light. A white dwarf cannot have a mass more than 1. 4 solar masses: chandraselehar predicted that gravity would overcome the pressure of electron degeneracy. Accretion can cause a white dwarf to surpass its 1. 4 limit: the white dwarf collapses and dies in a white dwarf supernova. White dwarf supernova: always attain the same luminosity and are therefore useful in measuring distance, type i: no h in spectrum. **better than cepheid variable stars, due to their great luminosity (~10 billion suns)
