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| Home > Publications database > Investigation on gravitational star-disk encounters producing ʻOumuamua and Borisov-like Interstellar Objects |
| Home > Publications database > Investigation on gravitational star-disk encounters producing ʻOumuamua and Borisov-like Interstellar Objects |
| Master Thesis | FZJ-2020-05018 |
2020
Abstract: The recent discovery of two Inter-Stellar Objects (ISO) in our own Solar System has promptedastronomers to come up with theoretical explanations on how they are produced. Most newlyformed stars are initially surrounded by a protoplanetary disk. The main hypothesis is thatthese ISOs were planetesimals in such disks and that through one mechanism or another becameunbounded from their host stellar system. These same stars and their disks are preferentiallyformed in stellar clusters. The gravitational effects that result from the interaction betweendisks and stars are thus common and relevant for the understanding of the fate of such disks.Amongst these mechanisms there is the gravitational stellar fly-by encounter. The partialdestruction of the disk by the perturber star produces a varying number of unbounded plan-etesimals. Several studies have looked into the effects of stellar fly-bys on disks both for theco-planar prograde case and for inclined retrograde cases. They investigated properties such asfinal disk size or final fate of the test particles. However, the particles that become unboundhave attracted little attention so far. This work focuses on the particles that become unboundduring such fly-bys, contributing to the ISO population. We perform numerical simulationsof a range of parabolic inclined encounters with varying pertuber star masses and periastrondistances for the encounters. The parameter space explored in this work is relevant for a typ-ical young open stellar cluster environment. Here we focus on the relative amount and thevelocities of ISOs produced during such fly-bys. We found that the velocity distribution ofunbounded test particles varies according to the different possible combination of parameters.Nonetheless, the final ejection velocities were found to be in the range between 0.3 km/s and3.0 km/s. Using the results of this particular work along with the available literature on thevelocities of ISOs produced by other sources, we can make a quantitative distinction betweenthe different types of ISOs. As a follow up study, more precise cluster simulations accountingfor the IMF function, binary populations and viscous disks would provide a more realistic andcomprehensive study of the production of ISOs in clusters.
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