HR 858

HR 858 is a star with a planetary system located 104[1] light years from the Sun in the southern constellation of Fornax. It has a yellow-white hue and is visible to the naked eye but is a challenge to see with an apparent visual magnitude of 6.4.[2] The star is drifting further away with a radial velocity of 10 km/s.[1] It has an absolute magnitude of +3.82.[5]

HR 858

Position of HR 858 in Fornax
Observation data Epoch J2000.00      Equinox J2000.00
Constellation	Fornax
Right ascension	02h 51m 56.246s[1]
Declination	−30° 48′ 52.26″[1]
Apparent magnitude (V)	6.382[2]
Characteristics
Evolutionary stage	F6V[3] + M[4]
Spectral type	Main sequence
B−V color index	+0.484[5]
Astrometry
Radial velocity (Rv)	+10.07±0.13[1] km/s
Proper motion (μ)	RA: 123.229±0.070[1] mas/yr Dec.: 105.788±0.151[1] mas/yr
Parallax (π)	31.2565 ± 0.0700[1] mas
Distance	104.3 ± 0.2 ly (31.99 ± 0.07 pc)
Absolute magnitude (MV)	+3.82[5]
Details[4]
A
Mass	1.145+0.074 −0.080 M☉
Radius	1.310+0.0240 −022 R☉
Luminosity	2.348+0.069 −0.071 L☉
Surface gravity (log g)	4.19±0.10 cgs
Temperature	6,201±50 K
Metallicity [Fe/H]	−0.14±0.08 dex
Rotational velocity (v sin i)	8.3±0.5 km/s
Age	2.28±1.30[6] Gyr
B
Radius	0.17±0.04 R☉
Temperature	2,800±300 K
Other designations
CD−31°1148, GC 3443, HD 17926, HIP 13363, HR 858, SAO 193951, TOI 396[7]
Database references
SIMBAD	data

This object is a slightly-evolved F-type main-sequence star with a stellar classification of F6V,[3] which indicates it is generating energy through core hydrogen fusion. It is roughly two[6] billion years old and is spinning with a projected rotational velocity of 8.3 km/s. The star has 1.1 times the mass of the Sun and 1.3 times the Sun's radius. It is radiating 2.3 times the luminosity of the Sun from its photosphere at an effective temperature of 6,201 K.[4]

There is a faint co-moving stellar companion, designated component B, at an angular separation of 8.4″. This corresponds to a projected separation of 270 AU. It is most likely a red dwarf star.[4]

In May 2019, it was announced to have at least 3 exoplanets as observed by transit method of the Transiting Exoplanet Survey Satellite. All three are orbiting close to the host star and appear to be super-Earths, about twice the size of the Earth. Components 'b' and 'c' may be in a 3:5 mean motion resonance.[4]