Abstract:
Concepts of the fundamental difference between com„ets and asteroids have recently been significantly adjusted. Several dozen Main Belt asteroids have exhibited signs of cometary activity (comas, tails), earning the name “Main Belt comets.” Using ground-based instruments, such active asteroids were detected primarily by imaging, so only the most pronounced manifestations of the activity of Main Belt asteroids have been observed. Undoubtedly, the number of asteroids with more moderate activity is incomparably larger. Detecting weak activity with ground-based instruments requires innovative approaches. The conventional method of broadband photometry and low-resolution spectroscopy turned out to be just such an effective tool. The use of this technique in [1–4] enabled a mass-scale study of a weak form of the activity of primitive-type asteroids, called sublimation-driven dust activity (SDA). SDA results in the formation of a temporary, fairly rarefied dust exosphere around the asteroid, detectable by broadband photometry. Modern concepts of active asteroids are reviewed. Attention is focused on manifestations of SDA and models of light scattering in dusty exospheres of asteroids. The mass character of SDA and its possible driving mechanisms are discussed.
Keywords:asteroids, active asteroids, sublimation activity, light scattering on dust particles, asteroid collisions
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