Discovery of Giant ‘Monster’ Planet Shatters Previously Held Formation Theory

A giant planet – the existence of which was previously thought extremely unlikely – has been discovered by an international collaboration of astronomers, led by Dr. Daniel Bayliss and Professor Peter Wheatley from the University of Warwick’s Astronomy and Astrophysics Group.

NGTS-1b, a massive, 986°F (530° Celsius or 800° Kelvin) hot ball of gas revolving around a red M-dwarf star 600 light years away from Earth, is the largest planet compared to the size of its companion star ever discovered in the universe. It is approximately the same size as Jupiter and orbits a small star with a radius and mass half that of our sun.

Its mere existence challenges previously accepted theories of planet formation which state that a planet this enormous in size could not be formed by such a small star. According to these theories, small stars can readily form rocky planets but do not gather enough material together to form gigantic, Jupiter-sized planets.

The planet is a hot Jupiter, at least as large as the Jupiter in our own solar system, but with around 20% less mass. It is very close to its star at about 2.8 million miles apart from each other – just 3% of the 93-million-mile distance between Earth and the Sun. A year on NGTS-1b — the time it takes to completely orbit once around its star — occurs every 2.6 Earth days.

Dr. Daniel Bayliss, a lead author of the research, commented:

“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 researchers spotted the planet using the state-of-the-art Next-Generation Transit Survey (NGTS) — a wide-field observing facility made of a compact ensemble of telescopes, designed to search for transiting planets on bright stars — run by the Universities of Warwick, Leicester, Cambridge, Queen’s University Belfast, Observatoire de Genève, DLR Berlin and Universidad de Chile.

NGTS-1b is the first planet outside our solar system to have been discovered by the NGTS facility, which is situated at the European Southern Observatory’s Paranal Observatory in Northern Chile.

The researchers made their discovery by monitoring patches of the night sky over many months, and detecting red light from the star with innovative red-sensitive cameras. They noticed dips in the light from the star every 2.6 days, implying that a planet was orbiting and periodically blocking starlight.

Using these data, they then tracked the planet’s orbit around its star and calculated the size, position and mass of NGTS-1b by measuring the radial velocity of the star – finding out how much the star ‘wobbles’ during orbit, due to the gravitational tug from the planet, which changes depending on the planet’s size.

As red M-dwarf stars are the most common type in the universe, scientists now believe there may be many more planets like this.

University of Warwick Professor Peter Wheatley, another leading co-author of the research, claims the discovery was no easy task:

“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.

“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.”

The astronomers’ report, NGTS-1b: a hot Jupiter transiting an M-dwarf, will be published in the Monthly Notices of the Royal Astronomical Society.

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