Collisional process on Comet 9/P Tempel 1: Mass loss of its dust and ice by impacts of asteroidal objects and its collisional history

Abstract

We have studied the collisional process on the nucleus of Comet 9/P Tempel 1 (T1) and estimated the mass loss of surface materials due to the impacts of asteroidal objects. The mass loss rate is around ∼2×10 5 kg yr −1 , which is smaller than that of water sublimation of ∼6×10 9 kg yr −1 . We then estimated the number density of craters formed by asteroid impacts to infer the collisional history of T1. We found that the time necessary to accumulate the crater population on T1 is as long as ∼ a few 10 4 years, suggesting that T1 crossed the asteroid belt region more than ∼ a few 10 4 years ago, though this estimated time may be reduced to several thousands of years by taking into account the influence of the sublimation process on the crater size. Alternatively, the total period of the recent orbit, in which the perihelion distance is small enough to cause significant sublimation by erasing a large number of small craters, may be less than ∼2×10 3 years.

2007 Outburst of 17p/Holmes: The Albedo and the Temperature of the Dust Grains

“…Thanks to advances in our understanding of small asteroids in the main belt, we are able to estimate the possibility of the asteroid impact quantitatively. To estimate the impactor size and impact frequency, we follow the method written in Yamamoto et al (2010). The total mass of impact ejecta m e (r) escaping from 17P/Holmes surface can be written by a scaling formula for the crater radius and the total mass of impact ejecta escaping from a target body (Yamamoto et al 2010), …”