Do red dwarfs eventually become white dwarfs?
According to this image:
..a red dwarf will eventually degenerate into a white dwarf once it no longer has hydrogen left to fuse, but when I read about white dwarfs from various sources it always seems to imply that white dwarfs come only from red giants. Can anyone please clarify this for me?
Yes thresher I've read that, it doesn't seem to answer my question.
No ron I didn't mean red giants, since I know very well that white dwarfs form from them. I said that in my question. Did you look at the image?
Phoenix and ronwiz: thank you very much for your answers, but they appear to contradict each other so I'm know nearer knowing the answer :(
- phoenixshadeLv 51 decade agoFavourite answer
No, red dwarfs do not become white dwarfs.
White dwarfs are the remaining core of helium-fusing red giant stars after they have shed their outer layers due to fluctuations in the unstable helium-burning core and hydrogen-burning shell.
Red dwarfs are not massive enough for helium fusion to ever begin, so they never get hot enough to go beyond "red." When their supply of hydrogen runs out, they simply cool and condense, eventually becoming helium-rich brown dwarfs that do not orbit another star.
However, red dwarfs consume their hydrogen fuel VERY slowly, and because of this have EXTREMELY long lifespans, theoretically approaching a trillion (that's 1,000 billion!) years. Indeed, any red dwarfs that formed near the initial condensation of matter would still exist today. Astrophysicists have placed a pretty high priority on searching for such ancient red dwarfs, because their composition should conform to the early composition of the universe and could thus confirm or falsify important predictions of big bang theory. However, their very low luminosity makes such stars very difficult to detect beyond our immediate stellar neighborhood.
EDIT: Mine is correct. A red dwarf never generates enough heat to become white. This requires the higher-core-temperature stage that main sequence go into when they become red giants. (Sorry, ronwiz, no offense.)
- ronwizfrLv 71 decade ago
Yes, it is currently believed that stars below a the mass of 0.7-0.8 solar mass, do not have the red giant phase. However this is only known theoretically. Here is an explanation.
In all main sequence star core Hydrogen is fused to Helium. The "burning" of Hydrogen produces a counter pressure to gravity that will stop the star from further shrinking.
After billions of years, when most of the Hydrogen fuel in the core has been used, fusion stops and the star begins to shrink again. The core will heat up further and other fusion reactions become possible.
As these reactions produces *more* pressure than hydrogen fusion the star will swell up to a Red Giant.
However, this is not the case for the smallest stars, because when they start to shrink the temperature and pressure in the core does not become high enough to kick start Helium fusion. Therefore the pressure to swell up the star to a Red Giant is never produced and these small stars go directly to the White Dwarf state, without passing the square Red Giant.
Now why is this know only theoretically? That's because small stars live so long that none of them is yet at the end of their lives: the Universe is just too young.
- opalLv 44 years ago
Novas contain binary stars wherein one attracts fabric off the different. The improve of recent fabric on the white dwarf ultimately chefs off interior the nova journey. Our sunlight would not have a binary twin.
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- Anonymous1 decade ago
yes and purple dwarfs become green dwarfs...
- 1 decade ago
Only when they stay indoors for a while.
- 1 decade ago
excuse me! but we are called "little people"!!!!!!!!!