‘Monster’ Planet Discovery Challenges Formation Theory

Artist’s illustration of a "hot Jupiter". Image Credit: NASA/CXC/M. Weiss

A new research presents the discovery of NGTS-1b, a hot-Jupiter transiting an early M-dwarf host in a P~2.6 days orbit discovered as part of the Next Generation Transit Survey (NGTS).

The planet has a mass of M~0.8 M(jupiter) making it the most massive planet ever discovered transiting an M-dwarf. NGTS-1b is the third transiting giant planet found around an M-dwarf, reinforcing the notion that close-in gas giants can form and migrate similar to the known population of hot Jupiters around solar type stars.

The existence of the 'monster' planet, 'NGTS-1b', challenges theories of planet formation which state that a planet of this size could not be formed around such a small star. According to these theories, small stars can readily form rocky planets but do not gather enough material together to form Jupiter-sized planets.

Such massive planets were not thought to exist around such small stars. The challenge now is to find out how common these types of planets are in the Galaxy.

M-dwarf stars as planetary hosts are of high interest. Two important recent discoveries in the field of exoplanets relate to planets orbiting M-dwarfs: Proxima Centauri and Trappist-1.

The low intrinsic luminosity of M-dwarfs also means that the habitable zone is very close to the host star and therefore it is much easier to detect potential habitable planets around these stars, compared to their more massive counterparts. Finally, M-dwarfs are the most populous stars in the Galaxy and hence understanding planet formation and planet frequency around these low mass stars greatly enhances our knowledge of the full population of planets in the Galaxy.

The discovery of NGTS-1b demonstrates the capability of NGTS to probe early M-dwarfs for transiting planets. In the full course of the survey, enough early M-dwarfs will be monitored to allow us to provide statistics for these host stars such as the frequency of hot Jupiters around early M-dwarfs.

Resources

NGTS-1b: A hot Jupiter transiting an M-dwarf - (arXiv)

‘Monster’ Planet Discovery Challenges Formation Theory

NuSTAR Probes Black Hole Jet Mystery

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