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Close Encounters of Stars in the Solar Neighborhood

Presentation #142.03 in the session “Sun and Solar System”.

Published onJan 11, 2021
Close Encounters of Stars in the Solar Neighborhood

Rogue stellar pertubers have been a candidate for the justification behind the disruption of our Solar Systems’ Oort Cloud. The gravitational influence of a foreign star approaching our own stellar debris disk would eject comets, ice, and possible Trans-Neptunian type objects from their typical distant orbits. Discovering and understanding the close encounters in our search can extend our knowledge of the dynamics of our own Solar Systems’ past and future. We present results from our search for stellar encounters of stars with possible Oort Clouds that may have debris disks similar to our own sun. We used two sets of stars: a group of 10 stars with evidence of Oort clouds from Baxter et al. 2018, and the 74,066 stars with complete positions and velocities in Gaia DR2 within 100 parsecs of the sun. We integrated each star’s orbit in a model of the Galactic potential 15 million years into the past and future, and searched for stars in the Gaia DR2 subsample that will pass within 1.5 parsecs of any of the target stars with possible Oort Clouds. We use Monte Carlo sampling to compute 95 percent confidence intervals for the perihelion distance of each encounter, the time at which it occurred, and the relative velocity at the time of closest approach. We then estimate the impulse each encounter exerts using fiducial values for the Oort cloud mass and size. We find that a typical star in our target sample experiences between 16 and 34 close encounters over the 30 Myr window, of which 87% come within 106 AU. In total, 88% of all encounters in our results are within 106 AU and 12% of all encounters are within 3×105 AU.

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