HD 158259

HD 158259 is a main sequence star located 88 light-years (27 parsecs) away in the constellation Draco. It hosts a system of at least five planets, discovered by the SOPHIE échelle spectrograph using the radial velocity method.^[2]

HD 158259

Observation data Epoch J2000      Equinox J2000
Constellation	Draco
Right ascension	17h 25m 24.055s[1]
Declination	52° 47′ 26.47″[1]
Apparent magnitude (V)	6.46[2]
Characteristics
HD 158259
Evolutionary stage	Main sequence
Spectral type	G0[2] (G5VmF9[3])
Astrometry
Radial velocity (Rv)	13.44±0.14[1] km/s
Proper motion (μ)	RA: −90.678[1] mas/yr Dec.: −49.702[1] mas/yr
Parallax (π)	37.0177±0.0199 mas[1]
Distance	88.11 ± 0.05 ly (27.01 ± 0.01 pc)
Absolute magnitude (MV)	4.27[4]
Details
Mass	0.985[1] M☉
Radius	1.3[1] R☉
Luminosity	1.6[1] L☉
Surface gravity (log g)	4.28[5] cgs
Temperature	6,068[5] K
Metallicity [Fe/H]	−0.20[5] dex
Rotation	18 days[2]
Rotational velocity (v sin i)	3.0[6] km/s
Other designations
HIP 85268, 2MASS J17252406+5247263, TYC 3888-1886-1, TOI-1462, GSC 03888-01886[7]
Database references
SIMBAD	data
Exoplanet Archive	data

Characteristics

HD 158259 is a G0 star with a rotation period of 18±5 days. More detailed analysis of the spectral assigns a class of G5V, but with the metal lines of an F9 star.^[3]

Planets

Five planets have been confirmed orbiting HD 158259, along with one unconfirmed planet. These planets were discovered by N.C. Hara et.al. by the radial velocity method, published in Astronomy & Astrophysics in April 2020.^[8] The innermost planet, HD 158259 b, was also observed to transit the star by TESS.^[2] The planets orbit in a nearly 3:2 orbital resonance, with the period ratios 1.5758, 1.5146, 1.5296, 1.5130, and 1.4480, respectively, starting from the innermost pairing.^[9] A dynamical analysis has shown that the system is stable.^[2] One of the planets, HD 158259 b, is a super-Earth; the rest, including the unconfirmed HD 158259 g, are mini-Neptunes.^[8]

The HD 158259 planetary system^[2][10][9]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	2.2 M🜨	0.034	2.177±0.44	<0.1	—	~1.2 R🜨
c	5.6 M🜨	0.046	3.432±0.00002	<0.1	—	—
d	5.4 M🜨	0.060	5.198±0.008	<0.1	—	—
e	6.1 M🜨	0.080	7.954±0.0016	<0.1	—	—
f	6.1 M🜨	0.105	12.03±0.0028	<0.1	—	—
g (unconfirmed)	6.9 M🜨	0.135	17.39±0.023	<0.1	—	—

See also

• List of exoplanets discovered in 2020 - HD 158259 b, c, d, e, and f