A giant planet, which should not exist according to planet formation theory, has been discovered around a distant star. The new research is presented in a paper recently accepted for publication in the journal Monthly Notices of the Royal Astronomical Society.
The existence of the 'monster' planet, NGTS-1b, challenges theories of planet formation which state that a planet of this size could not be formed around such a small star. According to these theories, small stars can readily form rocky planets but do not gather enough material together to form Jupiter-sized planets.
NGTS-1b however, is a gas giant—due to its size and temperature, the planet is known as a 'hot Jupiter," a class of planets that are at least as large as our solar system's very own Jupiter, but with around 20 percent less mass. Unlike Jupiter however, NGTS-1b is very close to its star – just 3 percent of the distance between Earth and the Sun, and completes an orbit every 2.6 days, meaning a year on NGTS-1b lasts two and a half Earth days.
In contrast, the host star is small, with a radius and mass half that of our sun. Professor Peter Wheatley from the University of Warwick commented on the complications this introduced: "Despite being a monster of a planet, NGTS-1b was difficult to find because its parent star is so small and faint." He went on to explain the significance of the discovery given the challenging circumstances "small stars like this red M-dwarf are actually the most common in the universe, so it is possible that there are many of these giant planets waiting to found."
