16 Lyrae

16 Lyrae
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Lyra
Right ascension 19h 01m 26.38262s
Declination +46° 56 05.1475
Apparent magnitude (V) 5.00
Characteristics
Evolutionary stage main sequence
Spectral type A6 IV or A7 V
B−V color index +0.186±0.005
Astrometry
Radial velocity (Rv)+4.36±0.21 km/s
Proper motion (μ) RA: +22.004 mas/yr
Dec.: −80.894 mas/yr
Parallax (π)25.7832±0.0688 mas
Distance126.5 ± 0.3 ly
(38.8 ± 0.1 pc)
Absolute magnitude (MV)+2.13
Details
Mass1.722±0.013 M
Radius1.644+0.025
−0.023
(equatorial)
1.622+0.023
−0.022
(polar) R
Luminosity10.45+0.30
−0.28
 L
Surface gravity (log g)4.28 cgs
Temperature8,028 (equator)
8,242 (polar) K
Rotational velocity (v sin i)85.1+16.3
−31.6
 km/s
Age401+31
−32
 Myr
Other designations
16 Lyr, NSV 11677, BD+46°2602, HD 177196, HIP 93408, HR 7215, SAO 48011, WDS J19014+4656A, GSC 03545-03041
Database references
SIMBADdata

16 Lyrae is a suspected astrometric binary star system in the constellation Lyra, located 126 light years away from the Sun based on parallax. It is visible to the naked eye as a dim, white-hued star with a combined apparent visual magnitude of 5.00. The system is moving further away from the Earth with a heliocentric radial velocity of +4.36 km/s. It is a suspected member of the Ursa Major Moving Group stream.

Cowley et al. (1969) found a stellar classification of A7 V for the visible component, matching an A-type main-sequence star that is generating energy through hydrogen fusion at its core. Abt and Morrell (1995) instead listed a class of A6 IV, suggesting it has left the main sequence and become a subgiant star.

16 Lyrae is 72% more massive than the Sun and irradiates 10.5 times the Sun's luminosity. It is 401 million years old with a high rate of spin, showing a projected rotational velocity of 85 km/s. The fast rotation make this star slightly oblate, with an equatorial radius of 1.644 R and a polar radius of 1.622 R. Its effective temperature also vary across its surface due to rotation, from 8,200 K in the poles to 8,000 K in the equator.

This system is a source for X-ray emission with a luminosity of 105.3×1020 W, which is most likely coming from the unseen companion.