Activating main belt comets by collisions

Autor(en)

Thomas Maindl, Nader Haghighipour, Christoph Schäfer, Roland Speith

Abstrakt

Since their identification as a new class of bodies by Hsieh and Jewitt in 2006 active asteroids (or Main Belt Comets, MBCs) have attracted a great deal of interest. Given that sublimation of volatile material (presumably water-ice) drives MBC activity, these bodies are probable candidates for delivering a significant amount of Earth's water. Dynamical studies suggest in-situ formation of MBCs as the remnants of the break-up of large icy asteroids. Also, collisions between MBCs and small objects might have exposed sub-surface water-ice triggering the cometary activity of these bodies. In order to advance the effort of understanding the nature of MBC activation, we have investigated these collision processes by simulating the impacts in detail using a smooth particle hydrodynamics (SPH) approach that includes material strength and fracture models. Our simulations cover a range of impact velocities (between 0.5 km/s and 5.3 km/s) and angles, allowing m-sized impactors to erode enough of an MBC's surface to expose volatiles and trigger its activation. We also varied the material strength of the active asteroid's surface to study its influence on crater depths and shapes. As expected, depending on the impact energy, impact angle, and MBC's material strength we observe different crater depths. Across all scenarios however, our results show that the crater depths do not exceed a few meters. This implies that if the activity of MBCs is due to sublimating water-ice, ice has to exist in no deeper than a few meters from the surface.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

University of Hawaii, Eberhard Karls Universität Tübingen

Seiten

156

Anzahl der Seiten

1

Publikationsdatum

02-2016

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/activating-main-belt-comets-by-collisions(d7941ee3-e4c8-43ab-bbc3-1c80361149c3).html