Delta1 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 53^m 48.4506^s
Declination	+36° 58′ 18.196″ / +37° 01′ 03.755″
Apparent magnitude (V)	5.569/9.8
Characteristics
Spectral type	B2.5V/K2III
U−B color index	−0.67/+1.288
B−V color index	−0.15/+1.224
Astrometry

Radial velocity (R_v)	−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) (secondary)	204.5±7.7°
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
SIMBAD	data

Delta¹ Lyrae (δ¹ 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]

References

1 2 "* del01 Lyr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 15, 2007.
1 2 "BD+36 3308". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 15, 2007.
1 2 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.

Stars of Lyra
Bayer	α (Vega) β (Sheliak) γ (Sulafat) δ¹ δ² ε^{1, 2} ζ¹ ζ² η (Aladfar) θ ι κ λ μ (Alathfar) ν¹ ν²
Flamsteed	16 17 19
Variable	R (13) S T V W RR RV RZ TT TZ UZ XY AY CC CN CY DM EP EZ FL HK HP HR KX MV V344 V361 V404 V473 V477 V478 V533 V542 V543 V545 V550 V558
HR	6845 6847 6853 6901 6968 6984 6997 7016 7017 7019 7030 7033 7041 7043 7044 7064 7073 7081 7112 7115 7118 7132 7140 7146 7162 7181 7202 7204 7212 7237 7238 7244 7253 7272 7280 7284 7302 7338 7345 7346 7359 7376 7382
HD	177830 180314 181068
Gliese	Gliese 758 GJ 4063
Kepler	7 8 9 14 19 20 24 25 26 30 37 38 46 53 55 59 60 62 65 75 83 88 91 92 93 94 95 98 100 102 103 104 105 109 128 130 131 138 177 238 277 279 282 350 410 444
Other	GSC 02634-01087 GSC 02652-01324 KSw 71 LHS 6343 2MASS 1835+3259 WASP-3 WASP-58 WISE 1828+2650
List

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