HD 133131

HD 133131 is a binary star in the constellation of Libra. It is roughly 168 light-years (51.5 parsecs) away from the Sun.^[2] It consists of two G-type main-sequence stars;^[2] neither are bright enough to be seen with the naked eye.

HD 133131

Observation data Epoch J2000      Equinox J2000
Constellation	Libra
Right ascension	15h 03m 35.80651s[1]
Declination	−27° 50′ 27.5520″[1]
Apparent magnitude (V)	8.40 + 8.42[2]
Characteristics
Spectral type	G2 + G2[2]
B−V color index	0.622[3]
Astrometry
Radial velocity (Rv)	-16.30 km/s
Proper motion (μ)	RA: 156.88 mas/yr Dec.: -136.07 mas/yr
Parallax (π)	19.4 ± 0.12 mas[4][5][6]
Distance	168 ± 1 ly (51.5 ± 0.3 pc)
Orbit[2]
Period (P)	~4240 yr
Details[2]
HD 133131 A
Mass	0.95 M☉
Surface gravity (log g)	4.39 ± 0.050 cgs
Temperature	5799 ± 19 K
Metallicity [Fe/H]	−0.306 ± 0.016 dex
Age	6.3[3] Gyr
HD 133131 B
Mass	0.93 M☉
Surface gravity (log g)	4.41 ± 0.045 cgs
Temperature	5805 ± 15 K
Metallicity [Fe/H]	−0.281 ± 0.013 dex
Age	5.9[3] Gyr
Other designations
CPD−27° 5116, Gaia DR1 6224633979686194688, HD 133131, HIP 73674[4]
HD 133131 A: CD−27 10194A, Gaia DR2 6224633983987510528, SAO 183128, TYC 6756-1541-1, 2MASS J15033543-2750330[5]
HD 133131 B: CD−27 10194B, Gaia DR2 6224633983987511552, SAO 183129, TYC 6756-867-1, 2MASS J15033579-2750273[6]
Database references
SIMBAD	HD 133131
	HD 133131 A
	HD 133131 B

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 133131 A is additionally depleted in heavy elements compared to HD 133131 B, indicating a possibly past planetary engulfment event for HD 133131 B.^[7]

Planetary system

In 2016 two planets orbiting HD 133131 A and one planet orbiting HD 133131 B were discovered utilizing the radial velocity method.^[2]

The HD 133131 A planetary system^[2]

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 133131 B planetary system^[2]

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

References

1. van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
2. Teske, Johanna K; Shectman, Stephen A; Vogt, Steve S; Díaz, Matías; Butler, R. Paul; Crane, Jeffrey D; Thompson, Ian B; Arriagada, Pamela (2016). "The Magellan PFS Planet Search Program: Radial Velocity and Stellar Abundance Analyses of the 360 AU, Metal-Poor Binary "Twins" HD 133131A & B". The Astronomical Journal. 152 (6): 167. arXiv:1608.06216. Bibcode:2016AJ....152..167T. doi:10.3847/0004-6256/152/6/167. S2CID 118852162.
3. Arriagada, Pamela (2011), "Chromospheric Activity of Southern Stars from the Magellan Planet Search Program", The Astrophysical Journal, 734 (1): 70, arXiv:1104.3186, Bibcode:2011ApJ...734...70A, doi:10.1088/0004-637X/734/1/70, S2CID 118384591
4. "HD 133131". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 29 September 2020.
5. "HD 133131 A". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 29 September 2020.
6. "HD 133131 B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 29 September 2020.
7. Oh, Semyeong; Price-Whelan, Adrian M.; Brewer, John M.; Hogg, David W.; Spergel, David N.; Myles, Justin (2017), "Kronos and Krios: Evidence for Accretion of a Massive, Rocky Planetary System in a Comoving Pair of Solar-type Stars", The Astrophysical Journal, 854 (2): 138, arXiv:1709.05344, doi:10.3847/1538-4357/aaab4d, S2CID 119076217