Google has no answer to the speed of how fast a red giant expands.


So... Useless knowledge.


I'm sitting here wondering how fast does a red giant explode.
The best google can do is tell me how long it will take BEFORE the sun turns into a red giant.

I want to know the velocity of how fast a red giant event happens.
Will it take 2 million years to reach earth, or 20 minutes?

I guess know one actually knows?


i guess it's situational, i guess only certain stars enter the red giant stage, and that family of candidates has, infinite? variety in dimenisons, so there might be a forumla or a family of forumulae that look at it, but i don't think there would be a single number. maybe it's like x meters for every y gigatons and a-z of other factors mixed in i have no idea.
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Sephiroth may know.



Event Starts - After 5.4 Billion Years
Event Ends - 12.167 Billion Years

Expanded Radius of Sun 1.192 or 1.2 AU
Total Expansion distance 177566700 km (255 times of current radius)

Time taken for expansion is dynamic

With R as the radius of Sun.

7.13 Billion years from the present (.11 in 1.73 billion years after the start of the main sequence)

10.00 Billion years from the present (.26 in 2.87 billion years after)

12.17 Billion years from the present (254.63 in just 2.17 billion years after)

Now you cant get static speed, velocity because its dynamic event involving tidal forces, gravitational pull and repulsion and different rate of expansion for different spheres of the sun at different times even in the last 200 million year main expansion phase. The rate of mass loss is the most dynamic thing and the rate of expansion is directly influenced by it.
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