Observations of rotationally-fissioned asteroids - in search of fresh material

TYPEAstrophysics Seminar
Speaker:David Polishook
Organizer:Hagai Perets
Time:14:30 - 15:30
Location:Lidow 620
Abstract:Asteroids that rotate too fast for their weak bodies disintegrate, but the process and its consequences are not clear and different theoretical models have been proposed.
We measured near-infrared spectroscopy of 30 asteroids that were rotationally-fissioned in the last ~2 million years, in order to search for spectral indications of “fresh”, young surfaces recently exposed due to the fission of the asteroid.
Using the range of fresh and “weathered” spectra we disentangle between different models of the rotational-fission mechanism. We show that this is a fast process (~tens of days) that includes the ejection of a large component of the fast rotating asteroid. This component orbits the asteroid in a chaotic trajectory that put it under the pressure of tides from the asteroid until it fissioned as well, spreading significant amount of fresh material, before it is lost in space.
In addition, we found two asteroids with “fresh” spectrum that is known for in the groups of near-Earth asteroids and meteorites. These are the first of their kind to be observed in the main-belt of asteroids by the full visible and infrared regime. This solidly demonstrates that asteroids with fresh surfaces are not limited to near-Earth asteroid population, further strengthening the connection between these groups.