Pi Cephei
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cepheus |
| Right ascension | 23h 07m 53.854s[1] |
| Declination | +75° 23′ 15.00″[1] |
| Apparent magnitude (V) | 4.419[2] |
| Characteristics | |
| Spectral type | G7III[3] / F5V[3] / A7V-A9V[4] |
| U−B color index | -0.46 |
| B−V color index | 0.8 |
| Variable type | None |
| Astrometry | |
| Radial velocity (Rv) | -18.6 ± 0.9 km/s |
| Proper motion (μ) | RA: 6.81 ± 1.05[1] mas/yr Dec.: -34.06 ± 0.88[1] mas/yr |
| Parallax (π) | 13.8 ± 0.41[4] mas |
| Distance | 236 ± 7 ly (72 ± 2 pc) |
| Absolute magnitude (MV) | 0.24 |
| Orbit[3] | |
| Primary | Pi Cephei Aa |
| Companion | Pi Cephei Ab |
| Period (P) | 556.72 ± 0.05 days |
| Semi-major axis (a) | 39.0 ± 3.9 Mas[4] |
| Eccentricity (e) | 0.297 ± 0.006 |
| Inclination (i) | 99.0 ± 2.5[4]° |
| Longitude of the node (Ω) | 109.2 ± 3.5[4]° |
| Periastron epoch (T) | 2,439,172.9 ± 1.6 |
| Argument of periastron (ω) (secondary) | 7.6 ± 1.2° |
| Semi-amplitude (K1) (primary) | 24.18 ± 0.15 km/s |
| Orbit[5] | |
| Primary | Pi Cephei A (Aa + Ab) |
| Companion | Pi Cephei B |
| Period (P) | 160 yr |
| Semi-major axis (a) | 0.84" |
| Eccentricity (e) | 0.58 |
| Inclination (i) | 28.4° |
| Longitude of the node (Ω) | 63.5° |
| Periastron epoch (T) | 1933.95 |
| Argument of periastron (ω) (secondary) | 115.3° |
| Details | |
| Mass | 6.88±0.69 M☉ |
| Radius | ? R☉ |
| Luminosity | ? L☉ |
| Temperature | ? K |
| Metallicity | ? |
| Rotation | ? |
| Age | ? years |
| Other designations | |
Pi Cephei (π Cep) is a trinary star located in the constellation Cepheus.[4] The inner pair of stars orbits in 1.5 years while the outer companion completes one orbit in about 160 years.[4]
Stellar system
Pi Cephei was found to have a visual companion star by Otto Wilhelm von Struve in 1843.[4] That the primary is itself a spectroscopic binary was first noticed by William Wallace Campbell in 1901 using photographic plates taken at Lick Observatory.[7]
References
- 1 2 3 4 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Vizier catalog entry
- ↑ Hauck, B.; Mermilliod, M. (1998). "Uvbybeta photoelectric photometric catalogue". Astronomy and Astrophysics Supplement 129: 431–433. Bibcode:1998A&AS..129..431H. doi:10.1051/aas:1998195.Vizier catalog entry
- 1 2 3 Scarfe, C. D.; et al. (1983). "Revised orbits for 105 Herculis and Pi Cephei A and a model for the Pi Cephei system". Monthly Notices of the Royal Astronomical Society 203: 103–116. Bibcode:1983MNRAS.203..103S. doi:10.1093/mnras/203.1.103.
- 1 2 3 4 5 6 7 8 Gatewood, George; et al. (2001). "Hipparcos and MAP Studies of the Triple Star π Cephei". The Astrophysical Journal 549 (2): 1145–1150. Bibcode:2001ApJ...549.1145G. doi:10.1086/319458.
- ↑ Baize, P. (1992). "Orbital elements of 17 binary stars". Astronomy and Astrophysics Supplement Series (in French) 92 (1): 31–42. Bibcode:1992A&AS...92...31B.
- ↑ "pi. Cep -- Star". SIMBAD Astronomical Database. Centre de données astronomiques de Strasbourg. Retrieved 2013-09-01.
- ↑ Campbell, William Wallace (1901). "Some recent results secured with the Mills spectrograph". Lick Observatory bulletin 1 (4): 22–25. Bibcode:1901LicOB...1...22C. doi:10.5479/ADS/bib/1901LicOB.1.22C.
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