3 ms·

Study sheds light on white dwarf stars

9 points by sandebert 2y ago

rob74 2y ago
The full title is "Study sheds light on the white dwarf star, likely destroyer of our solar system" - and it's a really clickbaity one, I expected better of the Guardian TBH! The title sounds as if a white dwarf might come along and destroy the Solar System - instead, the Sun will eventually (in a few billion years) turn into one, and when that happens, of course the Solar System is done for - the details in the article are just about how exactly Earth and the other objects will meet their end. The consensus seems to be that Earth will be destroyed already during the earlier red giant phase.
- deleted 2y ago
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- microtherion 2y ago
  Now there's a comforting thought! (When I first learned about the future of the Sun as a child, I was honestly worried about earth being destroyed a few billion years from now. My time preferences have changed somewhat in the mean time.)
genman 2y ago
And how is Sun going to gain more mass to have more gravity than it has today? It is a poorly written article.
- mytailorisrich 2y ago
  It won't. They're only saying that when the Sun becomes a white dwarf some remaining objects may be thrown close enough to be shredded: "For the rest of the solar system, some of the asteroids located between Mars and Jupiter, and maybe some of the moons of Jupiter may get dislodged and travel close enough to the eventual white dwarf to undergo the shredding process we have investigated." Agreed that this is less sensational than the title suggests.
  - microtherion 2y ago
    But still, why won't these objects get shredded before, since the Sun will have had the same mass all along? Wouldn't gravity remain more or less the same during the entire stellar evolution?
    - BurningFrog 2y ago
      Because they'd be engulfed by the sun before getting that close to the center?
    - mytailorisrich 2y ago
      I know nothing about the topic but my best guess is that the white dwarf will have a mass comparable to the current Sun's mass but concentrated in a much smaller space, and so some objects may thus be able to orbit much closer and experience strong tidal forces as the gravitational well will be much steeper.
      - microtherion 2y ago
        So they would have been destroyed anyway, but instead of being swallowed by the Sun, they get ripped apart by gravity?
- pfdietz 2y ago
  What they glossed over was that after the Sun becomes a white dwarf, the remaining planets (and minor objects) will have orbits that can become unstable over time. One fate of objects on unstable orbits is to have their eccentricities pumped up to a point that they would pass very close to the white dwarf and be tidally disrupted. The fragments would then be on very elliptical orbits that would precess at different rates, leading to very high velocity collisions near the white dwarf, ultimately causing the remains to settle into a disk. Very small fragments would spiral in due to the Poynting-Robertson effect. https://en.wikipedia.org/wiki/Poynting%E2%80%93Robertson_effect https://en.wikipedia.org/wiki/Poynting%E2%80%93Robertson_eff...
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9 points by sandebert 2y ago

The full title is "Study sheds light on the white dwarf star, likely destroyer of our solar system" - and it's a really clickbaity one, I expected better of the Guardian TBH! The title sounds as if a white dwarf might come along and destroy the Solar System - instead, the Sun will eventually (in a few billion years) turn into one, and when that happens, of course the Solar System is done for - the details in the article are just about how exactly Earth and the other objects will meet their end. The consensus seems to be that Earth will be destroyed already during the earlier red giant phase.

deleted 2y ago
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microtherion 2y ago
Now there's a comforting thought! (When I first learned about the future of the Sun as a child, I was honestly worried about earth being destroyed a few billion years from now. My time preferences have changed somewhat in the mean time.)

genman 2y ago

And how is Sun going to gain more mass to have more gravity than it has today? It is a poorly written article.

mytailorisrich 2y ago
It won't. They're only saying that when the Sun becomes a white dwarf some remaining objects may be thrown close enough to be shredded: "For the rest of the solar system, some of the asteroids located between Mars and Jupiter, and maybe some of the moons of Jupiter may get dislodged and travel close enough to the eventual white dwarf to undergo the shredding process we have investigated." Agreed that this is less sensational than the title suggests.
- microtherion 2y ago
  But still, why won't these objects get shredded before, since the Sun will have had the same mass all along? Wouldn't gravity remain more or less the same during the entire stellar evolution?
  - BurningFrog 2y ago
    Because they'd be engulfed by the sun before getting that close to the center?
  - mytailorisrich 2y ago
    I know nothing about the topic but my best guess is that the white dwarf will have a mass comparable to the current Sun's mass but concentrated in a much smaller space, and so some objects may thus be able to orbit much closer and experience strong tidal forces as the gravitational well will be much steeper.
    - microtherion 2y ago
      So they would have been destroyed anyway, but instead of being swallowed by the Sun, they get ripped apart by gravity?
pfdietz 2y ago
What they glossed over was that after the Sun becomes a white dwarf, the remaining planets (and minor objects) will have orbits that can become unstable over time. One fate of objects on unstable orbits is to have their eccentricities pumped up to a point that they would pass very close to the white dwarf and be tidally disrupted. The fragments would then be on very elliptical orbits that would precess at different rates, leading to very high velocity collisions near the white dwarf, ultimately causing the remains to settle into a disk. Very small fragments would spiral in due to the Poynting-Robertson effect. https://en.wikipedia.org/wiki/Poynting%E2%80%93Robertson_effect https://en.wikipedia.org/wiki/Poynting%E2%80%93Robertson_eff...
deleted 2y ago
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