| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Hercules |
| Right ascension | 18h 02m 30.86234s[1] |
| Declination | +26° 18′ 46.8050″[1] |
| Apparent magnitude (V) | +6.99[2] |
| Characteristics | |
| Spectral type | G9V[3] |
| B−Vcolor index | 0.799±0.005[2] |
| Astrometry | |
| Radial velocity (Rv) | 20.16±0.12[1] km/s |
| Proper motion (μ) | RA: 389.772mas/yr[1] Dec.: -602.431mas/yr[1] |
| Parallax (π) | 45.4954±0.0167 mas[1] |
| Distance | 71.69 ± 0.03 ly (21.980 ± 0.008 pc) |
| Details | |
| Mass | 0.874 ± 0.012[3] M☉ |
| Radius | 0.999 ± 0.017[3] R☉ |
| Luminosity | 0.703 ± 0.017[3] L☉ |
| Surface gravity (log g) | 4.387 ± 0.014[3] cgs |
| Temperature | 5390±30[2] K |
| Metallicity [Fe/H] | 0.16 ± 0.05[3] dex |
| Rotation | 42.3+1.3 −0.7 d[2] |
| Rotational velocity (v sin i) | <2.0[2] km/s |
| Age | 13.4,[4]9.58+1.99 −1.55[2] Gyr |
| Other designations | |
| BD +26°3151,GJ 700.2,LFT 1388,SAO 85678,HIP 88348,2MASS J18023085+2618471 | |
| Database references | |
| SIMBAD | data |
HD 164922 is a seventh magnitudeG-type main sequence star in theconstellation ofHercules. To view it,binoculars or atelescope are necessary, as it is too faint to be visible to thenaked eye. It is 71.7light-years (22.0parsecs) distant from theEarth.[1] It will soon evolve away from themain-sequence and expand to become ared giant.[citation needed]
The name HD 164922 derives directly from the fact that the star is the 164,922nd star listed in theHenry Draper catalog. The designationb for its planet derives from the order of discovery. The designation ofb is given to the first planet found orbiting a given star, followed by the other lowercase letters of the alphabet.[5] In the case of HD 164922, only one was discovered, which was designatedb, followed by three more planets, which were designatedc,d, ande.[3][6]
HD 164922 is aG-type main sequence star that is approximately 87% the mass of and 99% the radius of theSun. It has a temperature of 5390K and is about 10 billion years old,[2] with estimates ranging as high as 13.4 billion years.[4] In comparison, theSun is about 4.6 billion years old[7] and has a temperature of 5778 K.[8]
The star is metal-rich, with ametallicity ([Fe/H]) of 0.16, or 144% the solar amount. This is particularly odd for a star as old as HD 164922. Its luminosity (L☉) is 70% of the solar luminosity.[3]
On 15 July 2006, a long periodSaturn-massexoplanet was announced orbiting around HD 164922. This planet orbits at 2.11 AU from the star with a low eccentricity value of 0.05.[9]
Almost exactly ten years later in 2016, another exoplanet, though less massive than the first planet, was discovered orbiting farther in from the star. This planet has aminimum mass of nearly 13 times that ofEarth, meaning it is possibly aNeptune-like planet.[3]
A third exoplanet, a hotsuper-Earth, was discovered in 2020,[2] and a fourth, Neptune-mass, in 2021.[6]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| d | ≥4.74±0.67 M🜨 | 0.1023±0.0012 | 12.4584+0.0019 −0.0023 | 0.18+0.17 −0.12 | — | — |
| e | ≥10.52+0.99 −0.97 M🜨 | 0.2292+0.0026 −0.0027 | 41.763±0.012 | 0.086+0.083 −0.060 | — | — |
| c | ≥14.3±1.1 M🜨 | 0.3411±0.0039 | 75.817+0.037 −0.038 | 0.096+0.088 −0.066 | — | — |
| b | ≥0.344±0.013 MJ | 2.149±0.025 | 1,198.5+3.2 −3.1 | 0.065+0.027 −0.029 | — | — |
