Delta1 Lyrae
| 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 |
| 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 (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) (secondary) | 204.5±7.7° |
| Other designations | |
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 "Simbad Query Result". Simbad. Retrieved October 15, 2007.
- 1 2 "Simbad Query Result". Simbad. 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.
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