Zeta1 Lyrae, Latinized from ζ1 Lyrae, is a binary star in the northern constellationofLyra. Based upon an annual parallax shift of 20.89 mas as seen from Earth,[1] the pair are located about 156 light years from the Sun. It is visible to the naked eye with an apparent visual magnitude of 4.37.[2]
Location of ζ Lyrae (circled) | |
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Lyra |
Right ascension | 18h44m 46.35735s[1] |
Declination | +37° 36′ 18.4171″[1] |
Apparent magnitude (V) | 4.37[2] |
Characteristics | |
Spectral type | kA5hF0mF2[3] |
U−B color index | +0.17[2] |
B−V color index | +0.18[2] |
Astrometry | |
Proper motion (μ) | RA: +29.04[1] mas/yr Dec.: +27.03[1] mas/yr |
Parallax (π) | 20.89 ± 0.17 mas[1] |
Distance | 156 ± 1 ly (47.9 ± 0.4 pc) |
Absolute magnitude (MV) | +0.94[4] |
Orbit[5] | |
Period (P) | 4.3 d |
Eccentricity (e) | 0.01 |
Periastron epoch (T) | 2440000.723 JD |
Argument of periastron (ω) (secondary) | 0.00° |
Semi-amplitude (K1) (primary) | 51.6 km/s |
Details | |
Mass | 2.36[6] M☉ |
Radius | 2.5[7] R☉ |
Luminosity | 31[8] L☉ |
Surface gravity (log g) | 3.7±0.1[9] cgs |
Temperature | 7914±112[9] K |
Metallicity [Fe/H] | 0.38±0.06[9] dex |
Rotational velocity (v sin i) | 47[10] km/s |
Age | 500[6] Myr |
Other designations | |
ζ1 Lyr, 6 Lyr, BD+37°3222, HD 173648, HIP 91971, HR 7056, SAO 67321.[11] | |
Database references | |
SIMBAD | data |
ζ1 Lyrae was discovered to be a spectroscopic binary by William Wallace Campbell and Heber Doust Curtis in 1905 from photographic plates taken at the Lick Observatory between 1902 and 1904.[12] The first orbit was calculated by Frank Craig Jordan of Allegheny Observatory in 1910 with results in good agreement with the most recent orbit.[13]
Several other faint stars within about an arc-minute have been listed as companions, but none are physically associated with ζ1 Lyrae.[14]
This is a single-lined spectroscopic binary system with an orbital period of 4.3 days and a nearly circular orbit with an eccentricity of 0.01.[5] The primary, component A, is an Am star with a stellar classification of kA5hF0mF2. This complex notation indicates that the spectral type determined solely from the calcium K line would be A5, the spectral type determined from other metallic lines would be F2, and the type determined from hydrogen lines would be F0.[3]
ζ1 Lyrae appears to be slightly variable, with a frequency of 0.65256 cycles per day and an amplitude of 0.0032 in magnitude.[15] The star has an estimated 2.36[6] times the mass of the Sun and around 2.5[7] times the Sun's radius. The position of this system is associated with an X-ray source with a luminosityof571.6×1020 W.[16]