HD 165259
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Apus |
| A | |
| Right ascension | 18h 12m 34.08358s |
| Declination | −73° 40′ 20.7691″ |
| Apparent magnitude (V) | 5.91 |
| B | |
| Right ascension | 18h 12m 33.47381s |
| Declination | −73° 40′ 20.9419″ |
| Apparent magnitude (V) | 9.03 |
| Characteristics | |
| A | |
| Spectral type | F5V |
| U−B color index | +0.05 |
| B−V color index | +0.46 |
| B | |
| Spectral type | G1 V |
| U−B color index | +0.74 |
| B−V color index | +1.06 |
| Astrometry | |
| Radial velocity (Rv) | 13.1±1 km/s |
| Absolute magnitude (MV) | +2.74 |
| A | |
| Proper motion (μ) | RA: −91.400 mas/yr Dec.: −254.341 mas/yr |
| Parallax (π) | 23.6778±0.0399 mas |
| Distance | 137.7 ± 0.2 ly (42.23 ± 0.07 pc) |
| B | |
| Proper motion (μ) | RA: −62.130 mas/yr Dec.: −241.999 mas/yr |
| Parallax (π) | 23.7101 ± 0.0338 mas |
| Distance | 137.6 ± 0.2 ly (42.18 ± 0.06 pc) |
| Orbit | |
| Primary | A |
| Companion | B |
| Period (P) | 450 yr |
| Semi-major axis (a) | 2.014″ |
| Eccentricity (e) | 0.3 |
| Inclination (i) | 46.7° |
| Longitude of the node (Ω) | 65.3° |
| Periastron epoch (T) | 2147.2 |
| Argument of periastron (ω) (primary) | 348.8° |
| Orbit | |
| Primary | Aa |
| Companion | Ab |
| Period (P) | 44.2 yr |
| Semi-major axis (a) | 0.373″ |
| Eccentricity (e) | 0 |
| Inclination (i) | 83.5° |
| Longitude of the node (Ω) | 105.2° |
| Periastron epoch (T) | 2027.22 |
| Argument of periastron (ω) (primary) | 0° |
| Details | |
| Aa | |
| Mass | 1.46 M☉ |
| Radius | 2.04 R☉ |
| Luminosity | 6.2 L☉ |
| Surface gravity (log g) | 3.92 cgs |
| Temperature | 6,411±218 K |
| Metallicity [Fe/H] | +0.26 dex |
| Rotational velocity (v sin i) | <5 km/s |
| Age | 1.8+0.1 −0.2 Gyr |
| Ab | |
| Mass | 0.73 M☉ |
| B | |
| Mass | 0.82 M☉ |
| Surface gravity (log g) | 4.3 cgs |
| Temperature | 5,328 K |
| Metallicity [Fe/H] | −0.22 dex |
| Other designations | |
| 67 G. Apodis, CD−73°1348, CPD−73°1888, GC 24731, HD 165259, HIP 89234, HR 6751, SAO 257571, WDS J18126-7340AB | |
| Database references | |
| SIMBAD | data |
HD 165259, also known as HR 6751 is a triple star system located in the southern circumpolar constellation of Apus. It has an apparent magnitude of 5.86, making it faintly visible to the naked eye. Parallax measurements place the system at a distance of 138 light years, and it is currently receding with a heliocentric radial velocity of 13.1 km/s.
HD 165259 consists of two main sequence stars, with stellar classifications of F5 V and G1 V, separated by two arc-seconds as of 2020. Speckle interferometry in 2008 revealed the primary to be a close binary itself, with the two components separated by 0.3″. By 2020, the separation had decreased to 0.2″. The outer pair take 542 years to complete a revolution while the inner pair complete their orbit within 32 years.
At present the primary is somewhat more massive than the Sun and a slightly enlarged radius of 2.0 R☉ as it is nearing the end of its main sequence life. It radiates at 6.2 times the luminosity of the Sun from its photosphere at an effective temperature of 6,411 K, giving a yellow-white hue. HD 165259A has an iron abundance 82% above solar levels, making it metal enriched. It is estimated to be nearly 2 billion years old and has a projected rotational velocity of less than 5 km/s. HD 165259B has 82% the mass of the Sun and an effective temperature of 5,328 K, giving an orange glow. The faint star orbiting the primary has a mass 73% that of the Sun.