HD 170069 (HR 6922) is a solitary[14] star in the southern constellation Telescopium. It has an apparent magnitude of 5.68,[2] allowing it to be faintly seen with the naked eye. The star is located at a distance of 590 light years[1] but is approaching closer with a heliocentric radial velocity of −18 km/s.[5] HD 170069 was designated as Tau Telescopii (τ Telescopii) before Benjamin Apthorp Gould dropped the title.[15]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Telescopium |
| Right ascension | 18h 29m 55.9414s[1] |
| Declination | −47° 13′ 13.9500″[1] |
| Apparent magnitude (V) | 5.68±0.01[2] |
| Characteristics | |
| Spectral type | K2 III[3] |
| B−V color index | +1.26[4] |
| Astrometry | |
| Radial velocity (Rv) | −18±4.3[5] km/s |
| Proper motion (μ) | RA: +28.685 mas/yr[1] Dec.: −12.434 mas/yr[1] |
| Parallax (π) | 5.5748 ± 0.1894 mas[1] |
| Distance | 590 ± 20 ly (179 ± 6 pc) |
| Absolute magnitude (MV) | −0.78[6] |
| Details | |
| Mass | 4.08[7] M☉ |
| Radius | 23.69[8] R☉ |
| Luminosity | 217[9] L☉ |
| Surface gravity (log g) | 1.46[10] cgs |
| Temperature | 4490±125[8] K |
| Rotational velocity (v sin i) | <1[11] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 170069 has a stellar classification of K2 III,[3] indicating that it is a red giant. It has 4.08 times the mass of the Sun[7] but has expanded to 23.69 times its girth.[8] It radiates at 217 times the luminosity of the Sun[9] from its enlarged photosphere at an effective temperature of 4,490 K,[8] giving an orange hue. Due to its evolved state, it has a projected rotational velocity that is less than 1 km/s.[11]