| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Scorpius |
| Right ascension | 17h 50m 38.35575s[1] |
| Declination | −40° 19′ 06.0723″[1] |
| Apparent magnitude (V) | 9.10[2] |
| Characteristics | |
| Spectral type | K3V[3] |
| B−Vcolor index | 0.964±0.066[2] |
| Astrometry | |
| Radial velocity (Rv) | −26.55±2.30[4] km/s |
| Proper motion (μ) | RA: +19.412mas/yr[1] Dec.: −25.799mas/yr[1] |
| Parallax (π) | 31.8624±0.0622 mas[1] |
| Distance | 102.4 ± 0.2 ly (31.38 ± 0.06 pc) |
| Absolute magnitude (MV) | 6.76[2] |
| Orbit[5] | |
| Period (P) | 8.4282388+0.0000014 −0.0000026 d |
| Semi-major axis (a) | 0.0859±0.0010 AU |
| Eccentricity (e) | 0.28126±0.00057 |
| Inclination (i) | 177.273+0.030 −0.027° |
| Longitude of the node (Ω) | 288.93+0.67 −0.73° |
| Periastronepoch (T) | 2457393.1874+0.0026 −0.0023 |
| Argument of periastron (ω) (secondary) | 28.70+0.13 −0.12° |
| Semi-amplitude (K1) (primary) | 1.8112+0.0013 −0.0016 km/s |
| Details[5] | |
| Mass | 0.797±0.042 M☉ |
| Radius | 0.770±0.017 R☉ |
| Luminosity | 0.413+0.056 −0.050 L☉ |
| Surface gravity (log g) | 4.567±0.028 cgs |
| Temperature | 5,270+190 −180 K |
| Metallicity [Fe/H] | −0.18+0.17 −0.19 dex |
| Rotational velocity (v sin i) | 1.9[6] km/s |
| Age | 5.7±4.7 Gyr[7] 3.1±2.7[8] Gyr |
| HD 162020 b | |
| Mass | 0.39±0.02[9] M☉ |
| Mass | 410.8+5.8 −5.3 MJup |
| Other designations | |
| CD−40°11894,HD 162020,HIP 87330,PPM 763039[10] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
HD 162020 is astar in the southernconstellation ofScorpius with a likelyred dwarf companion. It has anapparent visual magnitude of 9.10,[2] which is too faint to be visible to the naked eye. The distance to this system is 102light-years (31parsecs) based onstellar parallax.[1] It is drifting closer to theSun with aradial velocity of −27 km/s,[4] and is predicted to come to within ~18 light-years in 1.1 million years.[11]
This is an ordinaryK-type main-sequence star with astellar classification of K3V.[3] The age estimate is poorly constrained but it appears to have an intermediate age of several billion years. However, theactivity level suggests a younger star; the rotation rate of the star may have been increased through synchronization with the companion, resulting in a higher than normal activity for its age.[6]X-ray emission has been detected from this star.[12]
HD 162020 has 74%[7] of themass of the Sun and 73%[4] of theSun's radius. The abundance of iron is roughly the same as the Sun, suggesting a similarmetallicity. It is radiating just 25.8% of theluminosity of the Sun from itsphotosphere at aneffective temperature of 4,801 K.[4] The star is spinning with aprojected rotational velocity of 1.9 km/s.[6]
HD 162020 b is a companion, initially thought to be abrown dwarf, with aminimum mass of15.0 MJ. At the time of discovery, the actual mass was undetermined since theorbital inclination was not known. This object orbits very close to the star at adistance of0.075 AU with aneccentricity (ovalness) of 0.277. The object's distance from the star ranges from 0.054 to 0.096 AU. It has an extremely high semi-amplitude of 1,813 m/s. The discovery was announced on April 15, 2000 by theGeneva Extrasolar Planet Search Team.[13][6]
Despite the presence of this massive object in an eccentric orbit around the star, computer modelling done in 2017 (when the object was still thought to be a brown dwarf) showed it is still theoretically possible for an Earth-mass exoplanet to be occupying a dynamically-stable orbit in thehabitable zone of this star.[14]
Anastrometric measurement of this object's true mass was published in 2022 as part ofGaia DR3, revealing it to be 0.39 M☉ and thus likely ared dwarf star.[9] A full orbital solution was published in 2023.[5]
