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Beta Lyrae AB
Observation data
Epoch J2000.0 Equinox J2000.0 |
| Constellation |
Lyra |
| Right ascension |
18h 50m 04.8s |
| Declination |
+33° 21′ 46″ |
| Apparent magnitude (V) |
3.52 (3.4–4.3) |
| Characteristics |
| Spectral type |
B7Ve/A8Vp |
| U-B color index |
−0.56 |
| B-V color index |
0.00 |
| Variable type |
β Lyr |
| Astrometry |
|
| Radial velocity (Rv) |
−19.2 km/s |
| Proper motion (μ) |
RA: 1.10 mas/yr
Dec.: −4.46 mas/yr |
| Parallax (π) |
3.70 ± 0.52 mas |
| Distance |
approx. 900 ly
(approx. 270 pc) |
| Absolute magnitude (MV) |
−3.91 |
|
| Details |
|
| Mass |
2/12 M☉ |
| Radius |
19/15 R☉ |
| Luminosity |
2,500/230 L☉ |
| Temperature |
13,000/8,000 K |
| Metallicity |
? |
| Rotation |
? |
| Age |
? years |
|
| Orbit |
| Companion |
Beta Lyrae B |
| Semimajor axis (a) |
45.7" |
| Inclination (i) |
149° |
| Orbit |
| Companion |
Beta Lyrae C |
| Semimajor axis (a) |
46.6" |
| Inclination (i) |
248° |
| Orbit |
| Companion |
Beta Lyrae D |
| Semimajor axis (a) |
64.3" |
| Inclination (i) |
68° |
| Orbit |
| Companion |
Beta Lyrae E |
| Semimajor axis (a) |
66.9" |
| Inclination (i) |
318° |
| Orbit |
| Companion |
Beta Lyrae F |
| Semimajor axis (a) |
19" |
| Inclination (i) |
85.8° |
| Other designations |
Sheliak, 10 Lyrae, HR 7106, BD+33°3223, HD 174638, SAO 67451, AAVSO 1846+33, FK5 705, HIP 92420
|
Beta Lyrae (β Lyr / β Lyrae) is a binary star system approximately 882 light-years away in the constellation Lyra. Beta Lyrae has the traditional name Sheliak (occasionally Shelyak), from الشلياق šiliyāq, the Arabic name of the constellation Lyra.[1]
Animation showing how the light curve of a contact binary star changes as they orbit.
Beta Lyrae is an eclipsing semi-detached binary star system made up of a B7II star (primary star) and what is likely also a B-type star (secondary star). The brighter, less massive star (B7II) in the system has filled its Roche lobe and is undergoing mass transfer with the other star due to its evolutionary state. The secondary, more massive star has an accretion disk due to this mass transfer. This accretion disk blocks our view of the secondary star, making it difficult for astronomers to pinpoint what its stellar type is. The system also contains bipolar jets.
Beta Lyrae changes its apparent magnitude from +3.4 to +4.6 over a period of 12.9075 days. The two components of the main star are so close together that they cannot be resolved with optical telescopes, forming a spectroscopic binary.
Two other stars appear close to Beta Lyrae in the night sky, but are not part of the binary system. One, at an angular distance of 45.7", is of spectral type B7V, has an apparent magnitude of +7.2, and can easily be seen with binoculars. It is about 80 times as luminous as the Sun and is also a spectroscopic binary with a period of 4.34 days. The other, Beta Lyrae F, is magnitude 9.9v separation 86" and with a luminosity 7 times that of the Sun.
[edit] See also
[edit] Components
- ^ The word is apparently of non-Arabic origin, as it has no other meaning in Arabic, and cannot be identified with an Arabic triliteral root. (Edward William Lane, Arabic-English Lexicon)
[edit] External links
