WASP-42

WASP-42 is a K-type main-sequence star. Its surface temperature is 5315±79 K.^[6] WASP-42 is similar to the Sun in concentration of heavy elements, with metallicity ([Fe/H]) of 0.05±0.13, and is much older than the Sun at 11.3+1.5
−4.8 billion years.^[4] The star does exhibit starspot activity as is typical for its spectral class.^[2]

WASP-42

Observation data Epoch J2000      Equinox J2000
Constellation	Centaurus
Right ascension	12h 51m 55.5580s[1]
Declination	−42° 04′ 25.095″[1]
Apparent magnitude (V)	12.6[2]
Characteristics
Evolutionary stage	main-sequence star
Spectral type	K1V[2]
Astrometry
Radial velocity (Rv)	41.25[3] km/s
Proper motion (μ)	RA: −49.875[3] mas/yr Dec.: 4.963[3] mas/yr
Parallax (π)	5.6209±0.0153 mas[3]
Distance	580 ± 2 ly (177.9 ± 0.5 pc)
Details[4]
Mass	0.881+0.086 −0.081 M☉
Radius	0.850±0.035 R☉
Surface gravity (log g)	4.50±0.18[5] cgs
Temperature	5315±79[2] K
Metallicity [Fe/H]	0.05±0.13 dex
Rotational velocity (v sin i)	2.70±0.40 km/s
Age	11.3+1.5 −4.8 Gyr
Other designations
2MASS J12515557-4204249[1]
Database references
SIMBAD	data

Multiplicity surveys did not detect any stellar companions to WASP-42 in 2017.^[7]

Planetary system

In 2012, one planet, named WASP-42b, was discovered^[8] on a tight, mildly eccentric orbit.^[4] The planetary equilibrium temperature is 1021±19 K.^[2]

The WASP-42 planetary system^[4]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	0.501±0.034 MJ	0.0548+0.0017 −0.0018	4.9816872±0.0000073	0.062+0.013 −0.011	88.30+0.26 −0.23°	1.063±0.051 RJ