Hereford Arizona Observatory found fluctuations in what type of main-sequence star in Cygnus?
KIC 8462852 KIC 8462852 (also Tabby's Star or Boyajian's Star) is an F-type main-sequence star located in the constellation Cygnus approximately 1280 ly from Earth. Unusual light fluctuations of the star, including up to a 22% dimming in brightness, were discovered by citizen scientists as part of the Planet Hunters project, and, in September 2015, astronomers and citizen scientists associated with the project posted a preprint of an article describing the data and possible interpretations. The discovery was made from data collected by the "Kepler" space telescope, which observes changes in the brightness of distant stars to detect exoplanets.
Double periodic variable A Double Periodic Variable (DPV) is a type of binary star. As the name implies, the systems vary in brightness not only due to eclipses of one star by the other, but also on a cycle of roughly 33 times longer than the orbit. The star gaining mass from the other has a thick disk of material surrounding it, and the systems apparently lose mass cyclically into the interstellar medium over time. The cause for the secondary longer variability still is not established. The stars are rare, with 21 systems found in the Galaxy and more than 170 in the Magellanic Clouds (Abril 2016).