A team of professional and amateur astronomers using data from NASA’s Kepler mission has spotted the dusty tails of six exocomets orbiting KIC 3542116, a young, magnitude 10, spectral type F2V star located approximately 800 light-years from Earth. Their work is published by the Monthly Notices of the Royal Astronomical Society and available online at arXiv.org.
Artist’s impression of the comet passing a distant star. Image credit: Danielle Futselaar.
The newly-discovered exocomets are about the size of Halley’s Comet and orbit KIC 3542116 (also known as TYC 3134-1024-1 and 2MASS J19225293+3841415) once every 51 to 92 days.
The discovery marks the first time that the presence of an object as small as a comet has been inferred by observing dips in the intensity of light from a star. Such dips usually signal crossings of planets or other objects in front of the star, which momentarily block a small fraction of its light.
In this case things were different, the astronomers were able to pick out the comet’s tail, a trail of gas and dust.
They calculated that each comet blocked about one-tenth of 1% of the star’s light. To do this for several months before disappearing, the comet likely disintegrated entirely, creating a dust trail thick enough to block out that amount of starlight.
“It’s amazing that something several orders of magnitude smaller than the Earth can be detected just by the fact that it’s emitting a lot of debris,” said lead author Professor Saul Rappaport, of MIT’s Kavli Institute for Astrophysics and Space Research.
“It’s pretty impressive to be able to see something so small, so far away.”
“These six exocomets appear to have transited very close to their star in the past four years raises some intriguing questions — the answers to which could reveal some truths about our own Solar System,” said co-author Dr. Andrew Vanderburg, of the Harvard-Smithsonian Center for Astrophysics.
“Why are there so many comets in the inner parts of these systems? Is this an extreme bombardment era in these systems?”
“The ‘Late Heavy Bombardment’ was an important stage in the formation of our own Solar System when scientists believe a large number of asteroids ‘bombarded’ the rocky planets, and may have in fact been responsible for first bringing water to Earth.”
“In the future, NASA’s Transiting Exoplanet Survey Satellite (TESS) will continue the type of research done by Kepler,” the astronomers said.
“Studying exocomets could give us some insight into how bombardment happens in other solar systems.”
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S. Rappaport et al. 2017. Likely Transiting Exocomets Detected by Kepler. MNRAS, in press; doi: 10.1093/mnras/stx2735
