Pi Cephei
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Location of π Cephei (circled in red) | |
| 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] 4.61[3] + 6.75[4]) |
| Characteristics | |
| Spectral type | G7III[5] / F5V[5] / A7V-A9V[6] |
| U−B color index | −0.46[citation needed] |
| B−V color index | +0.8[citation needed] |
| 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 mas[6] |
| Distance | 236 ± 7 ly (72 ± 2 pc) |
| Absolute magnitude (MV) | 0.24 |
| Orbit[5] | |
| Primary | π Cep Aa |
| Companion | π Cep Ab |
| Period (P) | 556.72±0.05 d |
| Semi-major axis (a) | 39.0±3.9 mas[6] |
| Eccentricity (e) | 0.297±0.006 |
| Inclination (i) | 99.0±2.5[6]° |
| Longitude of the node (Ω) | 109.2±3.5[6]° |
| 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[7] | |
| Primary | π Cephei A (Aa + Ab) |
| Companion | π Cephei B |
| Period (P) | 162.8±2.8 yr |
| Semi-major axis (a) | 0.810±0.050″ |
| Eccentricity (e) | 0.5968±0.0067 |
| Inclination (i) | 30.0±3.0° |
| Longitude of the node (Ω) | 90.3±4.9° |
| Periastron epoch (T) | B 1934.573±0.35 |
| Argument of periastron (ω) (secondary) | 90.0±4.4° |
| Details[6] | |
| π Cep Aa | |
| Mass | 3.63±0.53 M☉ |
| Surface gravity (log g) | 3.05±0.11[8] cgs |
| Temperature | 5,226±92[8] K |
| Metallicity [Fe/H] | 0.29±0.05[8] dex |
| Age | 100[8] Myr |
| π Cep Ab | |
| Mass | 3.27±0.48 M☉ |
| π Cep B | |
| Mass | 1.93±0.23 M☉ |
| Other designations | |
| HD 218658, HR 8819, 33 Cephei, BD+74°1006, SAO 10629, HIP 114222[9] | |
| Database references | |
| SIMBAD | data |
Pi Cephei (π Cephei) is a trinary star located in the constellation Cepheus.[6] With a combined apparent magnitude of about 4.4,[2] the system is faintly visible to the naked eye. The inner pair of stars orbits in 1.5 years while the outer companion completes one orbit in about 160 years.[6]
Pi Cephei was found to have a visual companion star by Otto Wilhelm von Struve in 1843.[6] That the primary is itself a spectroscopic binary was first noticed by William Wallace Campbell in 1901 using photographic plates taken at Lick Observatory.[10]
References
[edit | edit source]- ^ a b c d Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). Vizier catalog entry
- ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).Vizier catalog entry
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b c d e f g h i Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b c d Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
