S u m m a r y :
A giant planet, orbiting a distant, small star, has been spotted—one that should not exist if the planet formation theory is real. The new findings are published in the journal Monthly Notices of the Royal Astronomical Society.
Monster Planet Around Small Star
The discovery of a huge planet—dubbed monster planet, and named NGTS-1b—around a distant star has left scientists puzzled. This planet should not be existing according to the planet formation theory: it is too big to have formed around a star so small. Rather, small stars can only have rocky planets of smaller sizes because they cannot gather sufficient material to generate planets like Jupiter. So, how does this monster planet even exist?
“The discovery of NGTS-1b was a complete surprise to us—such massive planets were not thought to exist around such small stars—importantly, our challenge now is to find out how common these types of planets are in the Galaxy, and with the new Next-Generation Transit Survey facility we are well-placed to do just that,” says lead author Daniel Bayliss from the University of Warwick.
Detecting the Planet’s Orbit
NGTS-1b got its name from the instrument used to identify it, The Next-Generation Transit Survey (or ‘NGTS’) which is composed of 12 telescopes to look into the heavens. It was detected after the study authors monitored regions of the night sky over a period extending over several months; they finally found red light emanating from the star using red-sensitive cameras. When they observed dips in the light of the star every 2.6 hours, they concluded the presence of a planet orbiting around it periodically, in that amount of time. They were ultimately able to detect the orbit of the planet, and they calculated its size, mass, and position, using the radial velocity of the star.
A Year Lasts 2.5 Days
NGTS-1b is a gas giant: it is super big and hot; it is categorised as a hot Jupiter, a group of planets that are comparative in size to our Jupiter, but with about 20% less mass. On the other hand, unlike Jupiter, NGTS-1b is in close proximity with its star, with only 3% of the distance between Earth and the sun. This means that it completes an orbit in 2.6 days only; one year on NGTS-1b is only 2.5 days on Earth.
The Star Behind the Planet
As for its star (a red M-dwarf), its radius and mass are half that of our sun. This is what made NGTS-1b difficult to identify. Peter Wheatley from the University of Warwick explains that the parent star being so small, and thus faint, NGTS-1b was challenging to find even with its monster size. But, given that such a big planet has been spotted around a small star, a type of star that is deemed to be quite common, there might be other similar giant planets out there in the universe.
“Having worked for almost a decade to develop the NGTS telescope array, it is thrilling to see it picking out new and unexpected types of planets. I’m looking forward to seeing what other kinds of exciting new planets we can turn up,” says Wheatley.