HD 164595
HD 164595 is a wide binary star system in the northern constellation of Hercules. The primary component of this pair hosts an orbiting exoplanet. The system is located at a distance of 92 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of 2.0 km/s. Although it has an absolute magnitude of +4.81, at that distance it is too faint to be viewed with the naked eye, having an apparent visual magnitude of 7.07. The brighter star can be found with binoculars or a small telescope less than a degree to the east-northeast of Xi Herculis. HD 164595 has a relatively large proper motion, traversing the celestial sphere at an angular rate of 0.222″ yr−1.
Position of star HD 164595 in the constellation Hercules | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hercules |
| Right ascension | 18h 00m 38.894s |
| Declination | +29° 34′ 18.92″ |
| Apparent magnitude (V) | 7.07 + 12.538 |
| Characteristics | |
| Spectral type | G2 V + M2.5 V |
| B−V color index | 0.635±0.005 |
| Astrometry | |
| Radial velocity (Rv) | 2.048±0.0007 km/s |
| Proper motion (μ) | RA: −138.982 mas/yr Dec.: 173.502 mas/yr |
| Parallax (π) | 35.402 ± 0.0146 mas |
| Distance | 92.13 ± 0.04 ly (28.25 ± 0.01 pc) |
| Absolute magnitude (MV) | +4.81 |
| Details | |
| HD 164595 A (primary) | |
| Mass | 1.081±0.054 M☉ |
| Radius | 1.057±0.053 R☉ |
| Luminosity | 1.023+0.049 −0.046 L☉ |
| Surface gravity (log g) | 4.44±0.05 cgs |
| Temperature | 5,790±40 K |
| Metallicity [Fe/H] | −0.06 dex |
| Rotational velocity (v sin i) | 0.1 km/s |
| Age | 4.5 Gyr |
| HD 164595 B (secondary) | |
| Mass | 0.455±0.046 M☉ |
| Radius | 0.464±0.018 R☉ |
| Temperature | 3,648±21 K |
| Rotation | 43.486848 d |
| Other designations | |
| Database references | |
| SIMBAD | data |
The spectrum of the primary, component A, presents as a G-type main-sequence star with a stellar classification of G2 V. It is considered an excellent solar twin candidate, although it has a lower logarithm of metallicity ratio, at −0.06 compared with 0.00, and a slightly younger age, at 4.5 versus 4.6 billion years. The estimated mass, radius, and luminosity of this star are all similar to the Sun, and the level of magnetic activity in the chromosphere is comparable to solar levels.
The secondary member, component B, is a magnitude 12.5 star at a projected separation of 2,509±27 AU from the primary. It is a small red dwarf of spectral class M2.5 V. Periodic variations in the light curve of this star suggest a rotation period of 43.5 days.