Triggering Comet-Like Activity of Main Belt Comets

Autor(en)

Nader Haghighipour, Thomas Maindl, Christoph Schäfer, Roland Speith, Rudolf Dvorak

Abstrakt

Main-belt comets (MBCs) have attracted a great deal of interest since their identification as activated asteroids by Hsieh and Jewitt in 2006. It has been suggested that the comet-like activity of these objects are due to the sublimation of sub-surface water-ice that has been exposed as a result of their surfaces being impacted by small (e.g, m-sized) bodies. We have examined the viability of this scenario by simulating impacts between m-sized impactors and km-sized targets using a smooth particle hydrodynamics (SPH) approach. We have carried out simulations for a range of impact velocities and angles, material type and strength, and water content of the target allowing m-sized impactors to erode enough of an MBC's surface to trigger its activation. Results indicate that for the range of impact velocities corresponding to those in the asteroid belt, the depth of an impact crater is slightly larger than 10 m suggesting that if the activation of MBCs is due to the sublimation of sub-surface water-ice, this ice has to exist no deeper than a few meters from the surface. Our simulations point to a clearly notable spread in the aggregated crater depths due to different impact energy, impact angles, and MBC's water contents showing deeper craters due to less overall material strength. Results also show that ice-exposure occurs in the bottom and on the interior surface of impact craters as well as the surface of the target where some of the ejected icy inclusions are re-accreted. Our results, in addition to demonstrating that the impact scenario is indeed a viable mechanism to expose ice and trigger the activity of MBCs, indicate that the activity of the current MBCs is likely due to ice sublimation from multiple impact sites and/or the water contents of these objects (and other asteroids in the outer asteroid belt) is larger than the 5% that is traditionally considered in models of terrestrial planet formation. We present details of our simulations and discuss their results and implications.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

University of Hawaii, Eberhard Karls Universität Tübingen

Publikationsdatum

10-2016

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/28411ac2-45a9-4d08-8f4d-3bd6d7361487