In article ,
Knut Ove Hauge writes:
That also mean that the
sun is in an expansion state, and I would like to know if anybody could
answer, what happens to the surface temperature when it expands. Is it
getting colder or hotter? I think it's getting hotter.

Pulsating variable stars get cooler when they expand. (Minimum
temperature is not exactly synchronized with maximum radius,
however.)

As for the Sun, I'm not aware of any evidence that it is expanding.
According to stellar evolution models, it should be expanding very
slowly (less than a part per billion per year), but I would not
expect that to be measurable.

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Steve Willner Phone 617-495-7123
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