Interloper: An Asteroid from Outside the Solar System

Professor Jonathan Katz, Department of Physics and McDonnell Center for the Space Sciences
January 26, 2018 at 12:00 pm
241 Compton
Event Description 

The recently (October, 2017) discovered Interstellar Object (ISO) 1I/2017 U1 entered the Solar System with a speed (at infinity) of 26 km/s and passed within about 0.25 AU of the Sun. Contrary to expectation, it had no surrounding dust; it is an asteroid, not a comet. Most strikingly, its brightness varies by a factor of 10 with a period of 7.5 hours, indicating that it is rotating and is prolate (cigar-shaped) with a ratio of long to short axes of at least 10. I will discuss its origin and properties and possible relation to white dwarf "pollution" and to Soft Gamma Repeaters.