WASP-50

WASP-50 is a G-type main-sequence star about 594 light-years away. The star is older than the Sun and slightly depleted in heavy elements compared to the Sun, and has a close to average starspot activity.^[3] Despite its advanced age, the star is rotating rapidly, being spun up by the tides raised by a giant planet on a close orbit.^[5]

WASP-50 / Chaophraya

Observation data Epoch J2000      Equinox J2000
Constellation	Eridanus
Right ascension	02h 54m 45.1342s[1]
Declination	−10° 53′ 53.025″[1]
Apparent magnitude (V)	11.44[2]
Characteristics
Spectral type	G9V[3]
Astrometry
Radial velocity (Rv)	25.76±0.69[1] km/s
Proper motion (μ)	RA: 3.383(20) mas/yr[1] Dec.: 8.913(17) mas/yr[1]
Parallax (π)	5.4865±0.0174 mas[1]
Distance	594 ± 2 ly (182.3 ± 0.6 pc)
Details
Mass	0.892+0.08 −0.074[4] M☉
Radius	0.843±0.031[4] R☉
Surface gravity (log g)	4.5±0.1[3] cgs
Temperature	5400±100[3] K
Metallicity	−0.12±0.08[3]
Rotation	16.30±0.50 d[5]
Rotational velocity (v sin i)	2.6±0.5[3] km/s
Age	8.57±2.86[5] Gyr
Other designations
Chaophraya, TOI-391, TIC 382391899, WASP-50, TYC 5290-462-1, GSC 05290-00462, 2MASS J02544513-1053530[2]
Database references
SIMBAD	data
Exoplanet Archive	data

The star was named Chaophraya in December 2019 by Thai amateur astronomers through NameExoWorlds.^[6]

Planetary system

In 2011 a transiting hot superjovian planet, WASP-50b (named Maeping in 2019^[6]) was detected.^[3] In 2022 its albedo was found to be no more than 0.44, meaning that the planet reflects less than 44% of the light irradiated by its host star. This allows the planetary equilibrium temperature to be constrained at 1393±42 K.^[7]

The WASP-50 planetary system^[4][8]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b / Maeping	1.437±0.068 MJ	0.0293±0.0013	1.955100±0.000005	0.009+0.011 −0.006[9]	84.88±0.27°	1.138±0.026 RJ