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The Question

(Submitted May 12, 2005)

I am interested in the time it takes a red giant to become a white dwarf? Specifically, I am thinking about the Sirius mystery concerning the ancient records of Sirius as a red star. Although most articles I have found say that it is impossible, under our current stellar evolutionary model, for it to have evolved into a white dwarf, no literature that I have found explains exactly the time needed for it to have become a white dwarf.

The Answer

The answer to your question likely depends on the mass of the star in question. However, if we consider the Sun, then according to a timeline posted by John Baez, a mathematical physicist at the University of California, it will take about 400 million years for the Sun to go from red giant to white dwarf.

You can see his timelines at the following web page:

We hope this helps!

Barbara & Veronica
For the Ask a High Energy Astronomer team

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