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SUMMARY:Nature and Origin of 'Oumuamua and 2I/Borisov - First Interstellar
  Visitors to the Solar System - Dr. Roman Rafikov (DAMTP\, Cambridge)
DTSTART:20191015T120000Z
DTEND:20191015T130000Z
UID:TALK129211@talks.cam.ac.uk
CONTACT:Chris Hamilton
DESCRIPTION:On October 19\, 2017 project Pan-STARRS discovered (for the fi
 rst time) a macroscopic interstellar object traversing the inner part of o
 ur Solar System. Due to its high speed (about 26 km/s at infinity) and sma
 ll size (several hundred meters)\, its observations were possible for only
  40 days after the discovery. However\, they presented us with many myster
 ies. In this presentation\, I will talk about several of them\, focusing o
 n the physical nature of 'Oumuamua. Despite the fact that it showed no dir
 ect signs of cometary activity (tail\, coma\, gas and dust emissions\, etc
 .)\, a detection of its non-gravitational acceleration has been interprete
 d as a sign of cometary activity. I will explain why this cometary interpr
 etation suffers from a variety of problems that make it very unrealistic. 
 I will also talk about the theory for the origin of 'Oumuamua\, based on t
 he assumption of its asteroidal nature. According to this model\, such obj
 ects are formed during tidal disruption events of planets and asteroids or
 biting white dwarfs. Signatures of such catastrophic events are known to u
 s observationally (pollution of the atmospheres of white dwarfs with metal
 s\, compact discs around them)\, providing additional support to this idea
 . In this talk I will also cover the discovery and current status of obser
 vations of the second interstellar visitor to the Solar System\, comet 2I/
 Borisov discovered on August 30 of this year.
LOCATION:MR14\,  Centre for Mathematical Sciences\, Wilberforce Road\, Cam
 bridge
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