Colloquium on 5 May 2014
EXO-COMETS: Now you see them, now you don’t


Title: EXO-COMETS: Now you see them, now you don’t
Speaker: Barry Welsh
Date: Monday, 5 May 2014
Time: 15:00 - 16:00
Venue: SAAO Auditorium


It is thought that planets form out of cosmic dust grains that collide and stick to form larger and larger bodies. Once at the 1km size these icy rocky bodies are termed “planetesimals”, and are the building blocks of all planetary systems. In the case of our own Solar System, these small bodies have evolved to become comets or asteroids that mostly reside in either the Kuiper Belt or Oort cloud. Recent observations of young (< 50 Myr old) nearby A-type stars have revealed the spectral signatures of these "exo-comets" as they become gravitationally dragged towards the central star and release large amounts of evaporating gas. To date, exo-comet activity has been detected towards about a dozen of these young stars, all of which probably harbor (as yet undetected) orbiting exo-planets. In this talk we present an overview of exo-comets and the observing techniques required to detect them.

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