Crowdsourced effort finds cloud of comets around distant star

New Scientist : The images collected by the Kepler space telescope are examined with computer algorithms and are also made publicly available on a website called Planet Hunters. There, anyone can look at the pictures and try to identify possible exoplanets or other unusual phenomena. Exoplanets are usually found when they pass in front of their parent star, which causes a regular dip in the star’s brightness. On Planet Hunters, one star was found that exhibited dips in brightness that were irregular in both frequency and duration. When the signal was examined by Tabetha Boyajian of Yale University and her colleagues, they determined that it was not caused by variability in the star itself or by interference from other stars. They suggested that clumps of dust in orbit around the star could be causing the dim periods. But asteroid collisions wouldn’t produce enough dust, so Boyajian’s team concluded that a swarm of comets may have passed too near the star and were broken apart by its gravity. An eccentric orbit that leads to the cloud being further torn apart would explain all of the dips in the data and can be verified by further observations. The team was unable to track the star during the expected dim period in April 2015, but hopes to be able to do so in May 2017.