A large fraction (a third?) of all comets found (with observational bias thanks to SOHO) have been sungrazers, breaking up with perihelion of a few of Sun's radius. Is there reason to believe that this replenishes some kind of vulcanoid population of small objects? Or would they evaporate and be blown away by the Solar wind, or continue in their comet's orbit, or be ejected by Mercury's eccentricity? Would the constant replenishment, even now, not billions of years ago, help keep a population there in spite of all above?

Comet ISON

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    $\begingroup$ For very small orbiting particulates, the solar wind doesn't blow them out. They actually get pulled towards the sun by the Poynting–Robertson effect - see here: en.wikipedia.org/wiki/Poynting%E2%80%93Robertson_effect Slightly larger objects get pushed away. Beyond that, meteor showers are thought to come from comet debris, - see here: en.wikipedia.org/wiki/Meteor_shower#Origin_of_meteoroid_streams But that's not really an answer, so, just a comment. I like the Mercury question too. Not sure on that one. $\endgroup$ – userLTK Nov 7 '15 at 6:40
  • $\begingroup$ On evaporation . . Ices and most organics evaporate, or sublimate is probably more correct, even as far out as Ceres with direct exposure to the sun water-ice sublimates. But sublimated matter is still matter, so it still either gets get blown out of the inner solar system, drawn into the sun or onto a planet. "Dust" which is largely Silicates (SiO4-metal), has a high melting point and that would need to be closer to the sun than Mercury to begin to melt. science.uwaterloo.ca/~cchieh/cact/applychem/silicate.html and what-when-how.com/space-science-and-technology/comets $\endgroup$ – userLTK Nov 7 '15 at 7:00
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    $\begingroup$ @userLTK A surprisingly rich set of various non-gravitational radiation effects sort the orbits of objects according to size and composition and rotation. It would be interesting to learn what properties are required to prevail in Solar cis-Mercury orbits. $\endgroup$ – LocalFluff Nov 7 '15 at 7:22

The SOHO image you attached, provides some evidence, that most of the debris continues the trajectory of the original body. Most of the debris hence won't replenish the Vulcanoid population. But due to the disruptive event you get an additional delta-v, which may change the orbit a bit, however insufficient to slow down to a Vulcanoid orbit; compare the velocity of the comet near perihelion with the speed of sound as an order of magnitude estimate of the upper limit of the delta-v for debris. Dust may either be slowed down in this or in future orbits in the solar corona to end up in the Sun, or blown away by solar radiation pressure, again no Vulcanoids.

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  • $\begingroup$ Disruptive events don't neccessarily add delta-v... the same way comet "explosions" in the atmospere are not explosions, but disruptive events. Their increase in brightness comes from the sudden increase in surface area during burnup. $\endgroup$ – AtmosphericPrisonEscape Dec 4 '15 at 17:01
  • $\begingroup$ An upper bound estimate is sufficient in this case, to rule out formation of Vulcanoids.. $\endgroup$ – Gerald Dec 6 '15 at 2:45

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