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Old 01-26-2019, 05:53 PM   #4676 (permalink)
Vman455
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Quote:
Originally Posted by aerohead View Post
I went back through the workbook which accompanied the DVD astronomy course.
At end of life,massive stars become gravitationally unstable,experience a core collapse,blow away their outer plasma layers in an enormous release of energy.
Core remnants will be either a neutron star or black hole.
All pulsars are formed this way.
These events are irreversible.
Repeating 'nova' from the same source are impossible.
I hadn't heard of this phenomenon either, so I looked it up. Here's a write-up from Swinburne University of Technology:

"Recurrent novae are thought to arise in the same way as classical novae, through a white dwarf in a close binary system accreting a surface layer of hydrogen from a main sequence companion. Once the temperature at the bottom of this hydrogen layer reaches about 10 million Kelvin, a runaway thermonuclear reaction takes place which ejects the unburnt hydrogen into a rapidly-expanding shell around the white dwarf. This is the nova outburst.

While classical novae have only been seen in outburst once, recurrent novae have undergone at least two outbursts over the past century (since astronomers started taking notice!). The time interval between outbursts varies from 10 to 100 years, and astronomers propose that classical novae will be seen as recurrent novae given enough time.

The 8 recurrent novae astronomers know about tend to be slightly brighter than classical novae in their quiescent state. In outburst, they have the same brightness or are slightly fainter than classical novae, with the brightest maxima occuring for those novae with the shortest time interval between outbursts."

Note: none of this has anything to do with our Sun.
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