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‘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

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