Sharon Montgomery

Here Today, Gone Tomorrow: A Brief History of Exocomets

Comets are small icy Solar System bodies that display a coma on close approach to the Sun. Most are sequestered in vast reservoirs beyond the orbit of Neptune, and are visible to us only when flung inward by Jovian planets onto Sun-grazing orbits. Younger stellar systems (with large planets still in the process of forming) will likely be in a greater state of gravitational fluctuation. In these systems, the still-forming and migrating planets may throw large numbers of icy bodies towards the young central star. Under the right conditions, we may be able to detect these city-sized bodies.
Using absorption spectroscopy, Ferlet et al. (1987) published the first evidence of exocomets plunging towards the young star, Beta Pictoris. Astronomers have now observed evidence of cometary activity (though more subtle and less frequent) in the light towards more than 25 other stars. Caught briefly in the glare of the star, astronomers can use the transit information to study the composition of the comets. This talk is a review of exocometary research and the critical part it has played (and will continue to play) in our understanding of the early history of stellar systems, from planet-building to the habitability of those planets.