With over 2,000 exoplanets discovered, our view of the universe has radically changed. More and more planets are discovered every week, and while we might have gotten used to it, some are still able to surprise us, like this latest discovery.
Astronomers were able to detect a large gas giant living in a three-star system. The planet dubbed KELT-4Ab is about 685 light-years from Earth, it has one and a half times the mass of Jupiter and orbits its star, KELT-4A, every three days. Thanks to clear crisp images of the system, they were able to discover that its star has two other companions.
This discovery, published in the Astrophysical Journal, was possible thanks to KELT, the Kilodegree Extremely Little Telescope, which focus on planets orbiting very close to their host stars. The star KELT-4A was observed dimming every few days, indicating the presence of a close-by planet. Professor Justin Crepp from the University of Notre Dame used the Keck telescope to capture photos of the system.
“I found that there was a dot nearby, which we believed to be a star, making this a binary system,” Professor Justin Crepp said in a statement. “And then upon further review, I found that it was two dots. We wouldn’t have realized that without these photos.”
Four planets have so far been detected in the triple star system. This doesn’t mean that these systems are incredibly rare, it might be possible that they are just more difficult to detect. Either way, this discovery is very important to further our understanding of planet formation.
“When you first find these, you’re hunting and gathering. Once you have enough objects, we can start looking for patterns,” Crepp says.
KELT-4Ab is a "hot Jupiter," a giant gas planet orbiting closer to its star than Mercury is from the Sun. Until the discovery of the first exoplanet, scientists believed that gas giants would only be found far away from their host star, and not in such near orbits.
“We still think they formed far from their star, but then somehow migrated close to their stars. We also don’t know how they stop migrating. It is possible that companion stars drive the dynamics of planets such as to move the planets closer to the star,” Crepp added.
“We are trying to learn how planets get to their final resting places in orbits around stars. This discovery has implications for our understanding of planet formation and evolution.”