VW Cephei
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File:VWCepLightCurve.png A visual band light curve for VW Cephei, adapted from Kreiner and Winiarski (1981)[1] | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cepheus[2] |
| Right ascension | Template:RA[3] |
| Declination | Template:DEC[3] |
| Apparent magnitude (V) | 7.30Template:Snd7.84[4] |
| Characteristics | |
| A | |
| Spectral type | G8V[5] |
| B | |
| Spectral type | K0V[5] |
| Astrometry | |
| Proper motion (μ) | RA: +308.71 mas/yr[3] Dec.: +540.86 mas/yr[3] |
| Parallax (π) | 36.25±0.58 mas[3] |
| Distance | Script error: No such module "convert". ly (Script error: No such module "val". pc)[6] |
| Details[4] | |
| A | |
| Mass | 1.13 Template:Solar mass |
| Radius | 0.99 Template:Solar radius |
| Temperature | 5,050 K |
| Age | 9.029[7] Gyr |
| B | |
| Mass | 0.34 Template:Solar mass |
| Radius | 0.57 Template:Solar radius |
| Temperature | Script error: No such module "val". K |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Age | 9.029[7] Gyr |
| Orbit[4] | |
| Primary | A |
| Companion | B |
| Period (P) | 0.2783146[7] days |
| Semi-major axis (a) | Script error: No such module "val". (Script error: No such module "val".) |
| Inclination (i) | Script error: No such module "val".° |
| Other designations | |
| VW Cep, LHS 3565, SAO 9828, LTT 16039, BD+75 752, GJ 1255, GJ 9703, HD 197433, HIP 101750 | |
| Database references | |
| SIMBAD | data |
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VW Cephei (VW Cep) is an eclipsing contact binary of W Ursae Majoris-type located roughly at 90.6 light years from the Sun, whose two component stars share a common outer layer. Because the two components share their outer layers, as the components of W Ursae Majoris do, they have the same stellar classification, and are classified as yellow G-type main sequence dwarfs. The components take 0.2783 days (roughly 6.7 hours) to revolve around a common barycentre.[7]
Jan Schilt discovered that the star is an eclipsing variable, in 1926.[8]
Possible companion(s)
The orbital period of VW Cephei show variations, which was long thought to be likely caused by the presence of one more perturbing unseen object around the eclipsing binary.[6] Several publications have tried to set constrains to putative orbital period and minimum mass for unseen component. The most recent article proposes an orbital period of 29.8 years for a stellar object with roughly three fourths the Sun's mass and a high orbital eccentricity (e=0.66).[6] Nevertheless, hints of an additional body in the system still subsist and the authors infer a period of 77.46 years and eccentricity of 0.54 for unseen fourth component. The minimum mass is unclear, tentatively assumed being as small as 0.19 solar masses according to Pribulla et al. (2007).[9] In any case orbital solutions are still blurry and further calculations are needed to provide a more robust model.
A more recent analysis suggest that the period variations are more likely caused by mass transfer between components via the Applegate mechanism, rather than the presence of unseen companions.[4]
References
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