A group of astronomers has recently discovered the existence of a giant planet revolving around a small companion star. This find challenges a key theory regarding planet formation, according to which a planet of this size could not be formed by such a small star.
The research titled NGTS-1b: A Hot Jupiter Transiting an M-Dwarf will be published in the Monthly Notices of the Royal Astronomical Society.
The group of astronomers, led by Dr Daniel Bayliss and Professor Peter Wheatley from the University of Warwick’s Astronomy and Astrophysics Group, made the discovery using the state-of-the-art Next-Generation Transit Survey (NGTS), a wide-field observing facility with a compact ensemble of telescopes designed to search for transiting planets on bright stars. The NGTS is located in Northern Chile and run by the Universities of Warwick, Leicester, Cambridge, Queen’s University Belfast, Observatoire de Genève, DLR Berlin and Universidad de Chile.
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The existence of the ‘monster’ planet named NGTS-1b was previously believed to be highly unlikely by scientists. According to planet formation theories, small stars can readily form rocky planets but do not gather enough material to form Jupiter-sized planets.
The NGTS-1b is the largest planet compared to the size of its companion star ever discovered in the universe. Situated 600 light years away, it is a gas giant the size of Jupiter which orbits a star only half the size of our Sun.
The temperature on the planet is approximately 530°C and it contains 20% less mass compared to Jupiter. The NGTS-1b lies very close to its red M-dwarf star and has just 3% of the distance between Earth and the Sun. This means that a year on the planet lasts only two and a half days as it can complete an orbit around its star in just 2.6 days.
According to a statement, Dr Daniel Bayliss, the lead author of the research, said, “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,” he added.
The discovery was made by monitoring patches of the night sky over many months and detecting red light from the star with innovative red-sensitive cameras. Scientists noticed dips in the light from the star every 2.6 days, which meant that a planet was orbiting and periodically blocking starlight. Using this information, they were able to track the planet’s orbit around its star and calculate its the size, position and mass by measuring the radial velocity of the star – how much the star ‘wobbles’ during orbit, due to the gravitational tug from the planet, which changes depending on the planet’s size.
This new discovery has raised hopes that more of these planets will be found by the NGTS survey in the future.
Professor Peter Wheatley from the University of Warwick, who heads the NGTS facility, commented, “The NGTS-1b was difficult to find, despite being a monster of a planet, because its parent star is small and faint. Small stars are actually the most common in the universe, so it is possible that there are many of these giant planets waiting to found.”
He added, “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.”