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Impact Events as a Possible Mechanism to Initiate Sublimation–Dust Activity of Main-Belt Asteroids

As was shown in papers [1, 2] and other studies of these authors, sublimation–dust activity in some primitive-type asteroids of the Main asteroid belt (MAB) correlates with the near-perihelion position of asteroids in orbit. These results suggest that activity of this kind is induced by the sublimat...

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Published in:Astronomy reports 2022-11, Vol.66 (11), p.1098-1110
Main Authors: Shustov, B. M., Zolotarev, R. V., Busarev, V. V., Shcherbina, M. P.
Format: Article
Language:English
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Summary:As was shown in papers [1, 2] and other studies of these authors, sublimation–dust activity in some primitive-type asteroids of the Main asteroid belt (MAB) correlates with the near-perihelion position of asteroids in orbit. These results suggest that activity of this kind is induced by the sublimation (cometary) mechanism, i.e., release of dust particles from the surface of evaporating ice-bearing layers. It is considered that these layers become bared due to collisions between asteroids in the MAB. However, collisions may also directly result in ejecting the dust matter (the impact mechanism). Here, we consider the both mechanisms. The frequency and effectiveness of impacts have been quantitatively estimated. It has been shown that the collision frequency of projectile asteroids (impactors), the kinetic energy of which is higher than (1−3) × 10 10 J (sufficient to eject a significant amount of dust), with a target asteroid ~100 km across (by an example of asteroid 145 Adeona) is up to ~2 yr –1 . For the characteristic time of dust activity assumed at 0.01 yr, we found that, at any given time moment, among ~300 MAB asteroids larger than 100 km in diameter, several asteroids may be active due to the impact mechanism action. It is noted that this estimate is consistent with observations. To make the cometary mechanism effective, the collisions should be more powerful (the characteristic energy is 10 13 J) for excavating the ice-bearing layers over a sufficiently large area (up to 0.1 km 2 ). The frequency of powerful collisions is low, but the regions of uncovered ice-bearing layers exist for a long time. Outbursts of solar activity and heating during the asteroid’s passage along the perihelion part of the orbit may provide for the observed frequency of sublimation activity in large primitive asteroids of the MAB (there are about 200 of them). According to our model, approximately one large asteroid is active at any given time moment. Further observations are required to confirm this estimate.
ISSN:1063-7729
1562-6881
DOI:10.1134/S1063772922110178