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Most near-Earth asteroids are destroyed by the Sun, long before they get to Earth
In article ,
Yousuf Khan writes: "A new study finds that most asteroids and comets are destroyed in a drawn out, long hot fizzle, much farther from the Sun than previously thought." Mystery of disappearing asteroids solved | Astronomy.com http://www.astronomy.com/news/2016/0...teroids-solved The paper is in _Nature_ at http://www.nature.com/nature/journal...ture16934.html but you will need a subscription or pay to read more than the Abstract. I didn't find a preprint. The new result implies that many asteroids, especially dark ones, disintegrate at a few tens solar radii rather than at the much smaller distances one might expect. Despite the press release, I don't see anything about what fraction of asteroids disappear this way versus the fraction destroyed by hitting a planet. -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
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Most near-Earth asteroids are destroyed by the Sun, long beforethey get to Earth
On 23/02/2016 5:00 PM, Steve Willner wrote:
In article , Yousuf Khan writes: "A new study finds that most asteroids and comets are destroyed in a drawn out, long hot fizzle, much farther from the Sun than previously thought." Mystery of disappearing asteroids solved | Astronomy.com http://www.astronomy.com/news/2016/0...teroids-solved The paper is in _Nature_ at http://www.nature.com/nature/journal...ture16934.html but you will need a subscription or pay to read more than the Abstract. I didn't find a preprint. The new result implies that many asteroids, especially dark ones, disintegrate at a few tens solar radii rather than at the much smaller distances one might expect. Despite the press release, I don't see anything about what fraction of asteroids disappear this way versus the fraction destroyed by hitting a planet. Doesn't it simply mean that any and all asteroids that gets this close to the Sun, gets destroyed? Yousuf Khan |
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Most near-Earth asteroids are destroyed by the Sun, long before they get to Earth
In article ,
Yousuf Khan writes: Doesn't it simply mean that any and all asteroids that gets this close to the Sun, gets destroyed? "This close" is not a fixed distance. According to the paper, small and/or dark asteroids are destroyed at larger distances than big and/or reflective ones. However the uncertainty in how destruction distance varies with asteroid parameters isn't clear to me. It also isn't clear to me whether destruction has to be instantaneous, though the paper models it that way. It was always clear that asteroids passing close enough to the Sun would be destroyed. What's new is that "close enough" is somewhat farther than was known. The destruction mechanism that leads to this is still not known. -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
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Most near-Earth asteroids are destroyed by the Sun, long beforethey get to Earth
On 24/02/2016 5:05 PM, Steve Willner wrote:
It was always clear that asteroids passing close enough to the Sun would be destroyed. What's new is that "close enough" is somewhat farther than was known. The destruction mechanism that leads to this is still not known. Since they're talking about solar radii distances here, rather than something like AU, so could it be a combination of the Roche Limit of the Sun plus it's solar radiation pressure? Yousuf Khan |
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Most near-Earth asteroids are destroyed by the Sun, long before they get to Earth
In article ,
Yousuf Khan writes: Since they're talking about solar radii distances here, rather than something like AU, so could it be a combination of the Roche Limit of the Sun plus it's solar radiation pressure? Roche limit is about 3.5 solar radii even if the density is as low as 0.5, so that doesn't seem to be the mechanism. I don't see how solar radiation pressure could break up an object. The pressure would have to be different at different locations in such a way as to push the object apart. Expected surface temperatures at the relevant perihelion distances are in the range 700 to 1200 K. These are much higher than the boiling point of water (373 K) but rather lower than the melting point of rocks. The actual destruction mechanism is unknown, but that's no surprise. If there were an obvious destruction mechanism, the statistical result would have been expected. -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
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