科研之友
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摘要
Centaur 10199 Chariklo appears to have a varying spectral behavior. While three different spectral studies detect the presence of water ice at the surface, two more recent studies do not detect any absorption bands. In this article, we consider the possibility that Chariklo undergoes cometary activity that could be responsible for the observed spectral variations. We simulate its thermal evolution, finding that crystalline water ice should be present in the object core, and amorphous water ice should be found at the surface. Upon entering the inner solar system, Chariklo might experience some cometary activity due to ice crystallization if the obliquity is high, due to the adjustment of the internal structure to a new thermal equilibrium. No other activity is expected from this source, unless an external source like an impact provides the heat needed. In the case of such an event, we find that dust emitted in a coma is unlikely to be responsible for the observed spectral variations. In contrast, water ice grains in the coma would reproduce this pattern, meaning that the water ice detected after Chariklo's discovery was present in these grains and not on the object surface. Nonetheless, any activity would require an external additional heat source to be triggered, through an outburst, which might favor the spatial variations hypothesis.
- 出版日期2011-3
