HD 133131

HD 133131 is a binary star in the constellation of Libra. It is 168 light-years (51.5 parsecs) away from the Sun.^[3] It consists of two G-type main-sequence stars;^[3] neither are bright enough to be seen with the naked eye. The star was first catalogued as a binary in 1972.^[11][3]

HD 133131

Observation data Epoch J2000      Equinox J2000
Constellation	Libra[1]
A
Right ascension	15h 03m 35.44599s[2]
Declination	−27° 50′ 33.2195″[2]
Apparent magnitude (V)	8.40[3]
B
Right ascension	15h 03m 35.80805s[4]
Declination	−27° 50′ 27.5843″[4]
Apparent magnitude (V)	8.42[3]
Characteristics
A
Evolutionary stage	main sequence[2]
Spectral type	G2V[3]
B−V color index	+0.622[5]
B
Evolutionary stage	main sequence[4]
Spectral type	G2V[3]
B−V color index	+0.622[5]
Astrometry
A
Radial velocity (Rv)	−16.37±0.19[2] km/s
Proper motion (μ)	RA: +156.227 mas/yr[2] Dec.: −133.767 mas/yr[2]
Parallax (π)	19.4325±0.0265 mas[2]
Distance	167.8 ± 0.2 ly (51.46 ± 0.07 pc)
B
Radial velocity (Rv)	−15.70±0.18[4] km/s
Proper motion (μ)	RA: +159.010 mas/yr[4] Dec.: −139.133 mas/yr[4]
Parallax (π)	19.4131±0.0293 mas[4]
Distance	168.0 ± 0.3 ly (51.51 ± 0.08 pc)
Orbit[3]
Period (P)	~4240 yr
Details
HD 133131A
Mass	0.95[3] M☉
Radius	1.00[2] R☉
Luminosity	9.6[2] L☉
Surface gravity (log g)	4.39±0.050[3] cgs
Temperature	5,799±19[3] K
Metallicity [Fe/H]	−0.306±0.016[3] dex
Rotation	23 days[6]
Rotational velocity (v sin i)	4.0[7] km/s
Age	6.3[5] Gyr
HD 133131B
Mass	0.93[3] M☉
Radius	1.01[4] R☉
Luminosity	0.98[4] L☉
Surface gravity (log g)	4.41±0.045[3] cgs
Temperature	5,805±15[3] K
Metallicity [Fe/H]	−0.281±0.013[3] dex
Rotation	22 days[6]
Rotational velocity (v sin i)	7.0[7] km/s
Age	5.9[5] Gyr
Other designations
CPD−27°5116, HD 133131, HIP 73674[8]
HD 133131A: SAO 183128, TYC 6756-1541-1, 2MASS J15033543-2750330[9]
HD 133131B: SAO 183129, TYC 6756-867-1, 2MASS J15033579-2750273[10]
Database references
SIMBAD	The system
	A
	B
Exoplanet Archive	data

Both components, HD 133131 A and B, are very similar to the Sun but are far older, about 6 billion years old. They also have low metallicities (50% of solar abundance), and HD 133131A is additionally depleted in heavy elements compared to HD 133131B, indicating a possibly past planetary engulfment event for HD 133131 B.^[6]

Planetary system

In 2016, two planets orbiting HD 133131A and one planet orbiting HD 133131B were discovered utilizing the radial velocity method. All three are long-period giant planets.^[3]

The HD 133131A planetary system^[3]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥1.43 MJ	1.44	649	0.32	—	—
c	≥0.63 MJ	4.79	3925	0.20	—	—

The HD 133131B planetary system^[3]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥2.50 MJ	6.40	6119	0.62	—	—

See also

Other systems with multiple planet-hosting stars:

• HD 20781 & HD 20782
• WASP-94
• XO-2