HD 170069

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]

HD 170069

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
15 G. Telescopii, CD−47°12319, CPD−47°8894, GC 25216, HD 170069, HIP 90662, HR 6922, SAO 229064[12][13]
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]