Astronomy - Main sequence and red giants

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Discussion Overview

The discussion revolves around the disparity in the number of stars in the Main sequence compared to red giants, exploring the reasons behind this phenomenon. The scope includes theoretical considerations of stellar evolution and lifetimes of different star types.

Discussion Character

  • Exploratory, Conceptual clarification

Main Points Raised

  • One participant suggests that the Main sequence phase for moderate-low mass stars lasts billions of years, while the red giant phase is significantly shorter, lasting hundreds of millions to a billion years.
  • Another participant agrees and adds that not all Main sequence stars will evolve into red giants, as they must have a certain mass range or gain mass from a companion star.
  • A metaphor is used to illustrate the rarity of finding a star that will become a red giant, comparing it to finding a four-leaf clover on a specific day.

Areas of Agreement / Disagreement

Participants generally agree on the reasons for the greater number of Main sequence stars compared to red giants, but there is no consensus on the specifics of stellar evolution processes or the implications of mass requirements.

Contextual Notes

The discussion does not resolve the complexities of stellar evolution, including the specific conditions under which stars transition between phases or the implications of mass gain from companions.

tosv
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What is the main reason why there are so many more stars in the Main sequence in comparison with the number of red giants?
 
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I'd guess that the main sequence for moderate-low mass stars takes billions of years while the red giant phase is much much shorter. On the order of hundreds of millions to a billion or so years at most I think.
 
I'd agree with Drakkith on that point, plus not all main sequence stars will ever be red giants. They have to be born with 0.5 to 10 Solar masses worth of matter, or have it added to them by a companion during their lives. Akin to finding a four leaf clover on one specific day of the year.
 
Thanks for your replies!

I think my question have been answered now.
 

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