Delta1 Lyrae

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For other stars with this Bayer designation, see δ Lyrae.
Delta1 Lyrae[1][2]
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Lyra
Right ascension 18 h 53 m 43.5596 s/18 h 5 3m 48.4506 s
Declination +36° 58' 18.196"/+37° 01' 03.755"
Apparent magnitude (V) 5.569/9.8
Spectral type B2.5V/K2III
U−B color index −0.67/+1.288
B−V color index −0.15/+1.224
Radial velocity (Rv) −25.8/−49.0 km/s
Proper motion (μ) RA: 1.49/3.70 mas/yr
Dec.: −2.60/10.20 mas/yr
Parallax (π) 3.02 ± 0.56 mas
Distance approx. 1,100 ly
(approx. 330 pc)
Orbit[3], p. 412
Period (P) 88.352 days yr
Eccentricity (e) 0.37±0.03
Argument of periastron (ω)
Other designations
Delta1 Lyrae, 11 Lyrae, HR 7131, HD 175426, BD+36°3307, SAO 67537, HIP 92728, GC 25934, GSC 02650-02146, IDS 18502+3650, BD +36°3308, GSC 02650-01261
Database references

Delta1 Lyrae1 Lyr) is a binary star system in the constellation Lyra, approximately 1,100 light years away from Earth. The two stars complete an orbit around each other about once every 88 days. They are a spectroscopic binary, meaning the separation between the two is very small, and their orbital velocity is very high.[1][3]

The main star, IDS 18502+3650 A, is a bluish white star of the spectral type B2.5V, meaning it has a surface temperature of 11,000 to 25,000 kelvins.

Its 10th magnitude companion, IDS 18502+3650 B, is an orange giant star with the spectral type K2III. It therefore possesses a surface temperature of 3,500 to 5,000 kelvins and is cooler than the Sun, yet larger and brighter.[2]


  1. ^ a b "Simbad Query Result". Simbad. Retrieved October 15, 2007. 
  2. ^ a b "Simbad Query Result". Simbad. Retrieved October 15, 2007. 
  3. ^ a b Richardson, E. H. & McKellar, A.; Herbig (1957). "Redetermination of the spectrographic orbit of delta1 Lyrae". Publ. Dominion Astrophys. Obs. 10: 407–413. Bibcode:1991Obs...111..155G.