Scientists have recently discovered a gas giant exoplanet orbiting a small star, upending previous theories about planet formation. The massive exoplanet, called NGTS-4b, is approximately the size of Jupiter and is located 1,000 light years away from Earth.
Despite its mass, NGTS-4b is orbiting an M-type star, the smallest type of star that can still produce nuclear fusion. While larger stars are able to hold onto their protoplanetary discs, thus allowing them to form larger planets, it had been assumed that small stars wouldn’t be capable of this.
“This exoplanet is so big it was hard to believe it was orbiting such a tiny star,” said Dr. Daniel Bayliss, the leader of the team from the Universities of Warwick and Geneva who discovered the phenomenon. “We were able to take a closer look thanks to the Next-Generation Transient Survey, which allowed us to monitor millions of stars simultaneously.”
Dr. Bayliss and his team believe that NGTS-4b may have formed in a gas disc, then been dragged closer to its star through the process of tidal locking, which is also responsible for the tides of Earth’s oceans. As the planet travels around the star, its gravity pulls some of the star’s matter towards itself, slowly stripping away the star’s mass. Over time this process will eventually cause the planet to be destroyed, which means that the star could eventually end up with no planets in its system.
The discovery of NGTS-4b challenges the accepted models of planet formation and provides researchers with some interesting questions to explore. How is it possible for such a large planet to form around such a small star? Could other small stars have massive planets in orbit around them? Could the same processes be occuring at other stars?
For now the questions outnumber the answers, but the ongoing efforts of planet hunters could soon bring more insights to the mysterious universe outside of our own.