Comets are small icy bodies which vaporise on close approach to the Sun leaving behind a tail of dust and gas. Unlike asteroids, comets have generally not been subject to space-weathering and therefore are regarded as the unused building blocks of the Solar System, providing astronomers with pristine samples of the formation and evolution conditions of the early Solar System.
Much is to be gained by studying their composition, origin and dynamical history, as they provide important clues to the formation of life on Earth through the delivery of complex organic molecules and large quantities of water which may have laid the seeds of early organic chemistry on Earth.
This single frame Rosetta navigation camera image of Comet 67P/Churyumov-Gerasimenko. Credit: ESA/Rosetta/NavCam – CC BY-SA IGO 3.0
Young stellar systems, some of them many light years away, resemble the early Solar System by showing the hallmarks of being surrounded by a vast number of comets that you are now able to detect. These comets orbiting other stars, referred to as exocomets, give us the important foundation for which to make a comparison with the comets in our Solar System and allow us put their composition and dynamical distribution in perspective. Exocomets provide us with information valuable for understanding the composition of exoplanet atmospheres and may help us understand the early chemistry of Earth.
Exocomets where first discovered in the late 80’s, and given the term Falling Evaporating Bodies or FEB’s. Since then there has been a tremendous increase in the detection rate with exocomets having been detected around many stars.