HAT-P-54b, a transiting planet orbiting a late dwarf K star in NASA’s K2 mission field. Ground-based photometric light curves were combined with radial velocity measurements to determine the physical parameters of the system. HAT-P-54b has a mass of 0.760 ± 0.032 MJ, a radius of 0.944 ± 0.028 RJ, and an orbital period of 3.7998 d. The star has V = 13.505 ± 0.060, a mass of 0.645 ± 0.020 M⊙, a radius of 0.617 ± 0.013 R⊙, an effective Teff temperature = 4.390 ± 50K, and a subsolar metallicity of [Fe/H] = -0.127 ± 0.080.

HAT-P-54b has a radius that is less than 92% of known transiting planets with masses greater than Saturn’s, while HAT-P-54 is one of the lowest-mass stars known to host a hot Jupiter. Tracking high-precision photometric observations by the K2 mission promise to make this a well-studied planetary system.


Observations of HAT-P-54b

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