Questions tagged [red-giant]

Questions about red giants, large luminous low-mass stars in a late phase of stellar evolution.

9 questions with no upvoted or accepted answers
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What is the theoretical maximum variability a pulsating red giant can have such that a habitable planet can stay habitable for long periods of time?

I was reading about red giants and came across this statement: Some research suggests that, during the evolution of a 1 M☉ star along the red-giant branch, it could harbor a habitable zone for ...
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Dynamics of red giant hydrogen shell

From what I understood from this answer to How can a red giant grow so big? But this is not at all the way the shell fusing in a red giant self-regulates its fusion rate-- it cannot regulate its ...
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Jupiter/Saturn's fate after Sun goes red giant and planetary nebula?

The solar wind contributes a very small amount of matter to the gas giants. As the sun approaches the red giant phase, the solar wind increases significantly. 10% of the sun's mass lost as solar ...
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Where will the frost line be when the Sun becomes a red giant and what effect will it have on the solar system?

I understand the frost line is currently about 5.2 AU and earlier in the solar systems formation was 2.7 AU. But when the Sun becomes a red giant the frost line should move outward. I understand the ...
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Why red giants have cooler surface than MS stars?

I know that with increasing age and depletion of hydrogen in the core the radiation inside a main sequence (MS) star increases pushing the envelope/surface of the star outwards. What I don't ...
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Is a star with 2/3 solar masses and 9/10 solar radii still in the main sequence?

As far as I know, K-type and G-type stars (among others) grow in radius as they age, eventually leading to red giant phases. My question is, would a star that is about 0.66 solar masses and 0.94 solar ...
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Relation between initial mass and evolutionary phases lifetimes

Consider the following image (Source: An Introduction to Modern Astrophysics): There seems to be a relation between the initial mass/mass at the beginning of the MS and the time spent during ...
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37 views

Why is VX Sagittarii classified as spectral type M4-M10?

The largest and most luminous asymptotic-giant branch (AGB) star is VX Sagittarii. Wikipedia states that its spectral type is M4eIa-M10eIa (citing https://arxiv.org/pdf/astro-ph/0608438.pdf which in ...
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106 views

Could the Sun's planetary nebula be dangerous for the planets?

Since the Sun's mass isn't high enough it won't go supernova being a red giant but instead release a planetary nebula. So that seems to be kind of a substitute for a supernova. Would ejecting the ...