Main sequence stars: definition & life cycle

rod

Oct 22, 2019
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Near the end of the article, "The long lifetime of red dwarfs means that even those formed shortly after the Big Bang still exist today."

Back in the 1960s/1970s, there were various searches for Population III stars based upon red dwarf studies. Apparently this did not work out so Population III star sizes and masses were modified so they could burn out much faster.

http://phys.org/news/2016-06-astrophysicists-stars.html, "No one has yet observed the first stars that formed in the Milky Way. In all likelihood, they will never be directly observed, because the first stars are massive, ending their lives only a few millions years after their birth..."

https://phys.org/news/2020-06-hubble-early-universe.html, "New results from the NASA/ESA Hubble Space Telescope suggest the formation of the first stars and galaxies in the early Universe took place sooner than previously thought. A European team of astronomers have found no evidence of the first generation of stars, known as Population III stars, as far back as when the Universe was just 500 million years old..."
 
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Most stars are main sequence stars that fuse hydrogen to form helium in their cores - including our sun.

Main sequence stars: definition & life cycle : Read more
"The sun falls in between the spectrum, given [sic] it a more yellowish appearance."

*cough* Snow evenly reflects bright sunlight. So is it "yellowish as snow"?? My avatar is the Sun's color after mostly blue light (but not much) is removed due to atmospheric scattering (giving us a blue sky). Yellow isn't found even on the cooler limb.
 
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http://phys.org/news/2016-06-astrophysicists-stars.html, "No one has yet observed the first stars that formed in the Milky Way. In all likelihood, they will never be directly observed, because the first stars are massive, ending their lives only a few millions years after their birth..."
Yes. With only H & He and essentially no metals, they had to be very massive (up to 220x the Sun, IIRC) before they would become a star. Thus, they had short lives.

There is more than one paper on Pop III red dwarfs, however. Not that I understand why. They might exist in the MW halo where they are kept pristine by being far from the metals that would fall upon them if in the MW.
 

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