Nu Telescopii

Nu Telescopii, Latinized from ν Telescopii, is a slightly evolved star in the southern constellation Telescopium. It has an apparent visual magnitude of 5.33,^[4] meaning it is faintly visible to the naked eye. The object is relatively close to Earth, at a distance of 169 light years, and is approaching the Solar System with a heliocentric radial velocity of about −12 km/s.^[5]

ν Telescopii

Location of ν Telescopii (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Telescopium
Right ascension	19h 48m 01.1977s[1]
Declination	−56° 21′ 45.397″[1]
Apparent magnitude (V)	5.33±0.01[2]
Characteristics
Spectral type	A7 III/IV[3]
B−V color index	+0.20[4]
Astrometry
Radial velocity (Rv)	−12.4±4.2[5] km/s
Proper motion (μ)	RA: +90.983 mas/yr[1] Dec.: −137.406 mas/yr[1]
Parallax (π)	19.3152±0.0783 mas[1]
Distance	168.9 ± 0.7 ly (51.8 ± 0.2 pc)
Absolute magnitude (MV)	+1.86[6]
Details
Mass	1.85[7] M☉
Radius	1.94±0.09[8] R☉
Luminosity	15.6±0.1[9] L☉
Surface gravity (log g)	4.08+0.08 −0.07[10] cgs
Temperature	8,199±279[7] K
Metallicity [Fe/H]	−0.02[11] dex
Age	686[7] Myr
Other designations
ν Tel, 67 G. Telescopii, CPD−56°9290, FK5 739, HD 186543, HIP 97421, HR 7510, SAO 246271[12][13]
Database references
SIMBAD	data

Astronomers disagree about Nu Telescopii's spectral classification. It was initially categorized as Am star, with a classification of kA4mF3IV:.^[14] This indicates that the object has the calcium K-lines of an A4 star and the metallic lines of a F3 subgiant. However, Nu Telescopii was subsequently shown not to have a peculiar spectrum and was given a class of A9 Vn,^[15] indicating that it is an A-type main-sequence star displaying broad (nebulous) absorption lines due to its rapid rotation. It has since been classified as an evolved A7 star with either a blended luminosity class of a giant star or subgiant (III/IV)^[3], or only subgiant (IV).^[16]

Nu Telescopii has a mass of 1.85 M_☉ and an age of 686 million years.^[7] Its radius is 1.94 times that of the Sun^[8] and has an effective temperature of 8,199 K.^[7] These parameters yield a luminosity of 15.6 L_☉^[9] from its photosphere which, when viewed, has a white hue. Nu Telescopii's metallicity is around that of the sun.^[11] Its motion in space matches that of the IC 2391 cluster, making it a probable member.^[17]

Nu Telescopii has a faint, magnitude 9.3 companion star at an angular separation of 102 arc seconds along a position angle of 333°, as of 2010.^[18]