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Zorba
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Can anyone describe to me the path a low mass body takes as it leaves the main-sequence? Or is it the case that a low mass body just moves along the main sequence, down to the right?
Zorba said:Can anyone describe to me the path a low mass body takes as it leaves the main-sequence? Or is it the case that a low mass body just moves along the main sequence, down to the right?
Vanadium 50 said:Brown dwarfs are usually not considered stars, so they are not on the main sequence.[/QOUTE]
That is not a very good reason. In principle we can put any object in the Universe we like on the HR diagram, even though they have nothing to do with stellar evolution. Besides: brown dwarfs get their energy from gravitational contraction, just as some stars do in some parts of their life, so I would think they fit perfectly well on there in the same context.
Vanadium 50 said:There is no observational evidence as to what red dwarfs do when they leave the main sequence, since the universe is not old enough to have any examples. For the same reason, it's not been of intense theoretical interest.
There is _plenty_ of theoretical interest in low mass stellar evolution. The Universe is not old enough, so indeed we cannot find these objects, but that does not mean that we cannot calculate these objects. And we do. If stars leave the main sequence (i.e. did _did_ burn hydrogen in their core), they would indeed move upwards, along the Hayashi line: their core contracts, their envelope grows, so it cools down. They will become small variations of red giants. If they do not have enough mass to fuse helium, I guess they would just fade from there (and do some deuterium burning first).
Brown dwarfs will never move upwards, as they won't run out of the hydrigen they cannot even start burning. They will just cool down and fade.
A low mass post-main-sequence star is a star that has already burned through most of its hydrogen fuel and is moving towards the end of its life cycle. These stars have a lower mass compared to other stars and are typically cooler and smaller in size.
A low mass post-main-sequence star appears in the lower right region of the HR diagram, known as the red giant branch. As the star evolves, it moves towards the upper right region, towards the asymptotic giant branch.
After a low mass post-main-sequence star leaves the main sequence, it starts to expand and cool, becoming a red giant. As it continues to burn through its remaining fuel, it may experience pulsations and eventually shed its outer layers to become a white dwarf.
Low mass post-main-sequence stars play a crucial role in the chemical enrichment of the universe. As they evolve and release their outer layers, they eject heavy elements into the interstellar medium, which can then be used to form new stars and planets.
No, low mass post-main-sequence stars are not capable of supporting life. As they evolve, they become unstable and release large amounts of radiation and stellar winds, making their environment inhospitable for life.