HAT-P-20

HAT-P-20 is a K-type main-sequence star about 233 light-years away. The star has a strong starspot activity,^[5] and its equatorial plane is misaligned by 36⁺¹⁰
₋₁₂° with the planetary orbit.^[7] Although star with a giant planet on close orbit is expected to be spun-up by tidal forces, only weak indications of tidal spin-up were detected.^[10]

HAT-P-20

Observation data Epoch J2000      Equinox J2000
Constellation	Gemini[1]
Right ascension	07h 27m 39.9489s[2]
Declination	+24° 20′ 11.516″[2]
Apparent magnitude (V)	11.35[3]
Characteristics
Evolutionary stage	main sequence[2]
Spectral type	K3V[4]
Astrometry
Radial velocity (Rv)	-18.559 km/s
Proper motion (μ)	RA: −5.104(18) mas/yr[2] Dec.: −96.090(16) mas/yr[2]
Parallax (π)	14.0065±0.0176 mas[2]
Distance	232.9 ± 0.3 ly (71.40 ± 0.09 pc)
Details
Mass	0.798±0.018[5] M☉
Radius	0.744±0.011[5] R☉
Luminosity	0.19[6] L☉
Surface gravity (log g)	4.52±0.09[7] cgs
Temperature	4595±45[7] K
Metallicity	0.22±0.09[7]
Rotation	14.66±0.03 d[5]
Rotational velocity (v sin i)	2.0±0.5[7] km/s
Age	334[8] Myr
Other designations
Gaia DR2 869913435026514688, 2MASS J07273995+2420118[9]
Database references
SIMBAD	data

Planetary system

In 2010 a transiting hot super-Jovian planet was detected.^[4] Its equilibrium temperature is 996±19 K.

Size comparison of HAT-P-20 b and Jupiter

The HAT-P-20 planetary system^[4][5][7]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	7.59±0.12 MJ	0.03671±0.00027	2.8753172±0.0000003	0.0172±0.0016	86.3±0.1°	0.952±0.017 RJ