Planet with triple-star system found April 1, 2016 by Bob Yirka report Please Register or Log in to view the hidden image! This artist's concept of HD 1885 Ab, the first known planet to reside in a triple-star system, would have a similar sunset to KELT-4Ab. Both systems host a pair of stars distantly orbiting the planet-hosting single sun. Credit: NASA/JPL-Caltech A team of researchers working at the Harvard-Smithsonian Center for Astrophysics has announced the finding of a triple-star system—one that also as has a stable orbit planet in it. In their paper published in The Astronomical Journal, the team describes how they came to see that a binary system once thought to be a single star, was actually a pair of stars orbiting one another, and how that led to the revelation of the triple-star system. Read more at: http://phys.org/news/2016-04-planet-triple-star.html#jCp
http://iopscience.iop.org/article/10.3847/0004-6256/151/2/45/meta Abstract We report the discovery of KELT-4Ab, an inflated, transiting Hot Jupiter orbiting the brightest component of a hierarchical triple stellar system. The host star is an F star with Please Register or Log in to view the hidden image! = Please Register or Log in to view the hidden image! K, Please Register or Log in to view the hidden image! = Please Register or Log in to view the hidden image!, Please Register or Log in to view the hidden image! = Please Register or Log in to view the hidden image!, Please Register or Log in to view the hidden image! = Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image!, and Please Register or Log in to view the hidden image! = Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image!. The best-fit linear ephemeris is Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image!. With a magnitude of V ~ 10, a planetary radius of Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image!, and a mass of Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image!, it is the brightest host among the population of inflated Hot Jupiters (RP > 1.5RJ), making it a valuable discovery for probing the nature of inflated planets. In addition, its existence within a hierarchical triple and its proximity to Earth (210 pc) provide a unique opportunity for dynamical studies with continued monitoring with high resolution imaging and precision radial velocities. The projected separation between KELT-4A and KELT-4BC is 328 ± 16 AU and the projected separation between KELT-4B and KELT-4C is 10.30 ± 0.74 AU. Assuming face-on, circular orbits, their respective periods would be 3780 ± 290 and 29.4 ± 3.6 years and the astrometric motions relative to the epoch in this work of both the binary stars around each other and of the binary around the primary star would be detectable now and may provide meaningful constraints on the dynamics of the system.