Zeta2 Lyrae

Zeta² Lyrae is a single,^[10] white-hued star in the northern constellation of Lyra. It is a dim star that is just visible to the naked eye with an apparent visual magnitude of 5.74^[2] An annual parallax shift of 20.6 mas as seen from Earth provides a distance estimate of about 158 light years from the Sun. It is moving closer to the Sun with a radial velocity of −25 km/s.^[5]

For other stars with this Bayer designation, see ζ Lyrae.

Zeta² Lyrae

Observation data Epoch J2000      Equinox J2000
Constellation	Lyra
Right ascension	18h 44m 48.19919s[1]
Declination	+37° 35′ 40.5585″[1]
Apparent magnitude (V)	5.74[2]
Characteristics
Spectral type	F0 IVn[3] or F1Vnn[4]
U−B color index	+0.06[2]
B−V color index	+0.29[2]
Astrometry
Radial velocity (Rv)	−25.0±3.7[5] km/s
Proper motion (μ)	RA: +23.969[1] mas/yr Dec.: +23.461[1] mas/yr
Parallax (π)	20.6386±0.0443 mas[1]
Distance	158.0 ± 0.3 ly (48.5 ± 0.1 pc)
Absolute magnitude (MV)	+2.34[6]
Details
Mass	1.74[7] M☉
Radius	2.03±0.02[1] R☉
Luminosity	9.5±0.1[1] L☉
Surface gravity (log g)	3.94[7] cgs
Temperature	7,257+37 −3[1] K
Metallicity [Fe/H]	−0.36[1] dex
Rotational velocity (v sin i)	212[8] km/s
Age	1.223[7] Gyr
Other designations
ζ2 Lyr, 7 Lyr, BD+37°3223, GC 25678, HD 173649, HIP 91973, HR 7057, SAO 67324, WDS J18448+3736D[9]
Database references
SIMBAD	data

ζ¹ and ζ² Lyrae photographed by amateur astronomer David Chifiriuc in 2020. The separation between the two stars is 43.7″.

This star has a stellar classification of F0 IVn,^[3] suggesting it is an F-type subgiant star that is evolving away from the main sequence as its supply of hydrogen at the core has been consumed. The n suffix indicates "nebulous" lines caused by its rotation. It is spinning rapidly with a projected rotational velocity of 212 km/s.^[8] This is giving the star an oblate shape with an equatorial bulge that is an estimated 29% larger than the polar radius.^[11] The star is radiating approximately 9.6 times the Sun's luminosity from the photosphere at an effective temperature of about 7,000 K.^[1] It has 1.7^[7] times the mass of the Sun, twice the Sun's radius,^[1] and is about 1.2^[7] billion years old.

It is a suspected variable.^[9]