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‘Monster’ planet discovery challenges formation theory

last modified Oct 31, 2017 05:07 PM
‘Monster’ planet discovery challenges formation theory

Image credit: University of Warwick / Mark Garlick.

  • A giant planet – the existence of which was previously thought extremely unlikely – discovered around a small star by an international collaboration of astronomers, with the University of Cambridge taking a prominent role
  • NGTS-1b is the largest planet compared to the size of its host star ever discovered in the universe – it contradicts theories that a planet of this size could not form around such a small star
  • Discovered using the state-of-the-art Next-Generation Transit Survey observing facility*, designed to search for transiting planets around bright stars. NGTS-1b is the facility’s first detection.
  • NGTS-1b is 600 light years away from us – it is a gas giant the size of Jupiter which orbits a star only half the size of our Sun

A giant planet – the existence of which was previously thought extremely unlikely – has been discovered by an international collaboration of astronomers, with the University of Cambridge playing a prominent role. New research, in which Dr Edward Gillen is second author, has identified the unusual planet NGTS-1b - the largest planet compared to the size of its companion star ever discovered in the universe.

NGTS-1b is a gas giant planet six hundred light years away, the size of Jupiter, and orbits a small star with a radius and mass half that of our Sun. Its existence challenges theories of planet formation which state that a planet of this size should not be formed by such a small star.  According to these theories, small stars can readily form small rocky planets but do not gather enough material together to form larger Jupiter-sized planets.

Dr Edward Gillen, who determined the planet’s mass and radius through modelling the observational data, commented:

“NGTS-1b heralds an exciting start to planet discoveries with NGTS, as our first planet is something quite unexpected, which challenges our current understanding of what planets form around which stars. Furthermore, NGTS is monitoring many such small low-mass stars, which offers us the opportunity to determine how common planets like NGTS-1b are in the Galaxy.”

The research, ‘NGTS-1b: a hot Jupiter transiting an M-dwarf’, is published in the Monthly Notices of the Royal Astronomical Society. The paper can be accessed here: https://arxiv.org/pdf/1710.11099v1.pdf

* The NGTS facility is a joint project funded, built and operated by the Universities of Warwick, Cambridge, Leicester, Queens University Belfast, Observatoire de Genève, DLR Berlin and Universidad de Chile, along with support from the Science and Technology Facilities Council.

Contact person: Dr Edward Gillen (ecg41@cam.ac.uk).