Novae and Supernovae Type I1

Novae and Supernovae Type I1 - Novae and Supernovae Type Ia...

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Novae and Supernovae Type Ia An isolated white dwarf has a boring future: it simply cools off, dimming to invisibility. White dwarfs in binary systems where the companion is still a main sequence or red giant star can have more interesting futures. If the white dwarf is close enough to its red giant or main sequence companion, gas expelled by the star can fall onto the white dwarf. The hydrogen-rich gas from the star's outer layers builds up on the white dwarf's surface and gets compressed and hot by the white dwarf's gravity. Eventually the hydrogen gas gets dense and hot enough for nuclear reactions to start. The reactions occur at an explosive rate. The hydrogen gas is blasted outward to form an expanding shell of hot gas. The hot gas shell produces a lot of light suddenly. From the Earth, it looks like a new star has appeared in our sky. Early astronomers called them novae (``new'' in Latin). They are now known to be caused by old, dead stars. The spectra of a nova shows blue-shifted
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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