Astronomy - Main sequence and red giants

AI Thread Summary
The discussion focuses on the disparity in the number of main sequence stars compared to red giants, attributing it primarily to the longer lifespan of main sequence stars, which can last billions of years. In contrast, the red giant phase is significantly shorter, lasting hundreds of millions to a billion years. Additionally, not all main sequence stars evolve into red giants; only those with initial masses between 0.5 to 10 Solar masses can undergo this transformation. The analogy of finding a four-leaf clover highlights the rarity of red giants compared to the abundance of main sequence stars. Overall, the longevity of the main sequence phase is the key reason for the observed star population differences.
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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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