HIP 5158

HIP 5158

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Cetus[1]
Right ascension	01^h 06^m 02.050^s[2]
Declination	–22° 27′ 11.35″[2]
Apparent magnitude (V)	10.16[1]
Characteristics
Spectral type	K5V[3]
Apparent magnitude (B)	11.238[1]
B−V color index	1.078±0.001[1]
Astrometry
Radial velocity (Rv)	15.28±0.23[4] km/s
Proper motion (μ)	RA: 203.818±0.025 mas/yr[2] Dec.: −106.926±0.032 mas/yr[2]
Parallax (π)	19.3199 ± 0.0198 mas[2]
Distance	168.8 ± 0.2 ly (51.76 ± 0.05 pc)
Absolute magnitude (MV)	7.11[1]
Details
Mass	0.75±0.01[5] M☉
Radius	0.69±0.02[5] R☉
Luminosity	0.19±0.01[5] L☉
Surface gravity (log g)	4.63±0.02[5] cgs
Temperature	4,571±14[5] K
Metallicity [Fe/H]	0.10±0.07[3] dex
Rotation	42.3 days[3]
Age	4.5±3.2[5] Gyr
Other designations
CD–23°395, HIP 5158, SAO 166798, PPM 243575, LTT 617, NLTT 3632, 2MASS J01060202-2227111[6]
Database references
SIMBAD	data
Exoplanet Archive	data

HIP 5158 is a star with a pair of orbiting substellar companions, located in the equatorial constellation of Cetus,^[1] the whale. It has the older designation CD-23 395, which is derived from the Cordoba Durchmusterung catalogue of southern stars.^[6] Based on parallax measurements, it is located 169 light years from the Sun. It has an absolute magnitude of 7.11,^[1] but at that distance the star has an apparent visual magnitude of 10.16,^[1] which is too dim to be visible to the naked eye. The system is receding with a radial velocity of 15.3 km/s,^[4] and it has a relatively high proper motion, traversing the celestial sphere at an angular rate of 0.205″·yr⁻¹.^[7]

The spectrum of HIP 5158 matches an ordinary K-type main-sequence star,^[8] an orange dwarf, with a stellar classification of K5V.^[3] The age of this star is poorly constrained, but it appears to be comparable to the Sun.^[5] It is spinning slowly with a rotation period of around 42.3 days. Based on the abundance of iron, this star appears metal rich, having concentration of heavy elements equal to 125% of solar abundance.^[3] It has 75% of the mass of the Sun and 60% of the Sun's radius. The star is radiating just 19% of the luminosity of the Sun from its photosphere at an effective temperature of 4,571 K.^[5]

Planetary system

In 2009, a gas giant planet HIP 5158 b was found in orbit around the star. The quadratic drift in the radial velocities did indicate the presence of an additional outer planet in the system,^[3] which was confirmed in 2011. The large uncertainty in the mass of HIP 5158 c leaves in question whether this is an exoplanet or a brown dwarf.^[8]

The HIP 5158 planetary system^[3]^[8]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥1.42 MJ	0.89	345.72 ± 5.37	0.52 ± 0.08	—	—
c	≥15.04 MJ	7.7±1.88	9,018±3181	0.14±0.1	—	—

See also

• List of extrasolar planets

References

1. Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
2. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
3. Lo Curto, G.; et al. (2015). "The HARPS search for southern extra-solar planets. XXII. Multiple planet systems from the HARPS volume limited sample". Astronomy and Astrophysics. 512. A48. Bibcode:2010A&A...512A..48L. doi:10.1051/0004-6361/200913523.
4. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
5. Bonfanti, A.; et al. (2016). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics. 585: 14. arXiv:1511.01744. Bibcode:2016A&A...585A...5B. doi:10.1051/0004-6361/201527297. S2CID 53971692. A5.
6. "CD−23 395". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-11-10.
7. Luyten, W. J. (June 1995). "NLTT Catalogue (Luyten, 1979)". VizieR Online Data Catalog. Bibcode:1995yCat.1098....0L.
8. Feroz, F.; et al. (2011). "Bayesian evidence for two companions orbiting HIP 5158". Monthly Notices of the Royal Astronomical Society: Letters. 416 (1): L104 – L108. arXiv:1105.1150. Bibcode:2011MNRAS.416L.104F. doi:10.1111/j.1745-3933.2011.01109.x. S2CID 118517956.