Beta Lyrae
Beta Lyrae (β Lyrae, abbreviated Beta Lyr, β Lyr) officially named Sheliak (Arabic: الشلياق, Romanization: ash-Shiliyāq) (IPA: /ˈʃiːliæk/), the traditional name of the system, is a multiple star system in the constellation of Lyra. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 960 light-years (290 parsecs) distant from the Sun.
Location of β Lyrae in Lyra | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Lyra |
| Right ascension | 18h 50m 04.79525s |
| Declination | +33° 21′ 45.6100″ |
| Apparent magnitude (V) | 3.52 (3.25 – 4.36) |
| Characteristics | |
| Spectral type | B6-8II + B |
| U−B color index | −0.56 |
| B−V color index | +0.00 |
| Variable type | β Lyr |
| Astrometry | |
| A | |
| Radial velocity (Rv) | −19.2 km/s |
| Proper motion (μ) | RA: 1.90 mas/yr Dec.: −3.53 mas/yr |
| Parallax (π) | 3.39 ± 0.17 mas |
| Distance | 960 ± 50 ly (290 ± 10 pc) |
| Absolute magnitude (MV) | −3.82 |
| B | |
| Radial velocity (Rv) | −14±5 km/s |
| Proper motion (μ) | RA: 4.373±0.087 mas/yr Dec.: −0.982±0.098 mas/yr |
| Parallax (π) | 3.0065 ± 0.0542 mas |
| Distance | 1,080 ± 20 ly (333 ± 6 pc) |
| Orbit | |
| Primary | Aa1 |
| Companion | Beta Lyrae Aa2 |
| Period (P) | 12.9414 days |
| Semi-major axis (a) | 0.865±0.048 mas |
| Eccentricity (e) | 0 |
| Inclination (i) | 92.25 ± 0.82° |
| Longitude of the node (Ω) | 254.39 ± 0.83° |
| Details | |
| β Lyr Aa1 | |
| Mass | 2.97 ± 0.2 M☉ |
| Radius | 15.2 ± 0.2 R☉ |
| Luminosity | 6,500 L☉ |
| Surface gravity (log g) | 2.5 ± 0.1 cgs |
| Temperature | 13,300 K |
| Age | 23 Myr |
| β Lyr Aa2 | |
| Mass | 13.16 ± 0.3 M☉ |
| Radius | 6.0 ± 0.2 R☉ |
| Luminosity | 26,300 L☉ |
| Surface gravity (log g) | 4.0 ± 0.1 cgs |
| Temperature | 30,000 ± 2,000 K |
| Other designations | |
Sheliak, Shelyak, Shiliak, WDS 18501+3322 | |
| β Lyrae A: 10 Lyrae, AAVSO 1846+33, BD+33 3223, FK5 705, HD 174638, HIP 92420, HR 7106, SAO 67451/2 | |
| β Lyrae B: HD 174664, BD+33 3224, SAO 67453 | |
| Database references | |
| SIMBAD | β Lyrae |
| B | |
Although it appears as a single point of light to the naked eye, it actually consists of six components of apparent magnitude 14.3 or brighter. The brightest component, designated Beta Lyrae A, is itself a triple star system, consisting of an eclipsing binary pair (Aa) and a single star (Ab). The binary pair's two components are designated Beta Lyrae Aa1 and Aa2. The additional five components, designated Beta Lyrae B, C, D, E, and F, are currently considered to be single stars.