The discovery of a Jupiter-sized planet has challenged current theories of planetary formation by orbiting a star that should have been too small for the planet. NGTS-1b has been called a “monster” planet due to its size relative to its star. Is this new exoplanet really all that big, though, or is it just an unusually small star to be hosting a planet this big? The gas giant named NGTS-1b orbits a star that is classified as an M-dwarf, which is typically about half the mass and diameter of our sun, about 600 light-years away. According to current theories, an M-dwarf star would only be able to host rocky planets similar to Earth, Mars, and Venus.
NGTS-1b is a “hot Jupiter” with a diameter that is at least as big as Jupiter, but with 20% less mass, and is close enough to its host star to orbit about every 2.6 days. That made it easy for astronomers to first detect the planet by measuring dips in its host star’s light as the exoplanet makes its transit, and then calculate its mass and orbit by measuring how much it causes the star to “wobble”. This is the first exoplanet to have been discovered by the relatively recent Next Generation Transit Survey (NGTS).
The NGTS employed an array of small telescopes that operate in the 600-900nm band, making them useful for observing bright yet small and cool stars that normally aren’t included in the Kepler Telescope’s mission.
Dr Daniel Bayliss of the University of Warwick, who is the lead author for the study that discovered NGTS-1b, “The discovery of NGTS-1b was a complete surprise to us – such massive planets were not thought to exist around such small stars. This is the first exoplanet we have found with our new NGTS facility and we are already challenging the received wisdom of how planets form. Our challenge is to now find out how common these types of planets are in the Galaxy, and with the new NGTS facility we are well-placed to do just that.”
The discovery of NGTS-1b has been published in the Monthly Notices of the Royal Astronomical Society.