Astronomy:Pi Cephei
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Cepheus[1] |
| Right ascension | 23h 07m 53.854s[2] |
| Declination | +75° 23′ 15.00″[2] |
| Apparent magnitude (V) | 4.419[3] (4.61[4] + 6.75[5]) |
| Characteristics | |
| Spectral type | G7III[6] + F5V[6] + A7V-A9V[7] |
| U−B color index | −0.46[citation needed] |
| B−V color index | +0.8[citation needed] |
| Astrometry | |
| Radial velocity (Rv) | −27.33±0.01[8] km/s |
| Proper motion (μ) | RA: +6.81±1.05[2] mas/yr Dec.: −34.06±0.88[2] mas/yr |
| Parallax (π) | 13.8 ± 0.41[7] mas |
| Distance | 236 ± 7 ly (72 ± 2 pc) |
| Absolute magnitude (MV) | 0.24 |
| Orbit[6] | |
| Primary | π Cep Aa |
| Companion | π Cep Ab |
| Period (P) | 556.72±0.05 d |
| Semi-major axis (a) | 39.0±3.9 mas[7] |
| Eccentricity (e) | 0.297±0.006 |
| Inclination (i) | 99.0±2.5[7]° |
| Longitude of the node (Ω) | 109.2±3.5[7]° |
| 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[9] | |
| 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[7] | |
| π Cep Aa | |
| Mass | 3.63±0.53 M☉ |
| Surface gravity (log g) | 3.05±0.11[10] cgs |
| Temperature | 5,226±92[10] K |
| Metallicity [Fe/H] | 0.29±0.05[10] dex |
| Age | 100[10] Myr |
| π Cep Ab | |
| Mass | 3.27±0.48 M☉ |
| π Cep B | |
| Mass | 1.93±0.23 M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Pi Cep A | |
| Pi Cep B | |
Pi Cephei is a trinary star system located in the northern constellation Cepheus.[7] Its name is a Bayer designation that is Latinized from π Cephei, and abbreviated Pi Cep or π Cep. With a combined apparent magnitude of about 4.4,[3] the system is faintly visible to the naked eye. It is located at a distance of approximately 236 light-years (72 pc) from the Earth.
Pi Cephei was found to have a visual companion star by Otto Wilhelm von Struve in 1843.[7] The brighter member is itself a spectroscopic binary, which was first noticed by William Wallace Campbell in 1901 using photographic plates taken at Lick Observatory.[12] The inner pair of stars orbit with a period of 1.5 years while the outer companion completes an orbit in about 160 years.[7]
The primary component has a stellar classification of G7III,[6] presenting as an aging G-type giant star. At the age of 100 million years,[10] it has an estimated 3–4 times the mass of the Sun.[7] The lower mass components have classes of F5V[6] and A7V-A9V,[7] thus appearing to be main sequence stars.
References
- ↑ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A XHIP record for this object at VizieR.
- ↑ 2.0 2.1 2.2 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V. http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%2526A...474..653VFUL. Vizier catalog entry
- ↑ 3.0 3.1 Hauck, B.; Mermilliod, M. (1998). "Uvbybeta photoelectric photometric catalogue". Astronomy and Astrophysics Supplement 129 (3): 431–433. doi:10.1051/aas:1998195. Bibcode: 1998A&AS..129..431H.Vizier catalog entry
- ↑ Høg, E. et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27. Bibcode: 2000A&A...355L..27H.
- ↑ Fabricius, C. et al. (2002). "The Tycho double star catalogue". Astronomy and Astrophysics 384: 180–189. doi:10.1051/0004-6361:20011822. Bibcode: 2002A&A...384..180F.
- ↑ 6.0 6.1 6.2 6.3 6.4 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. doi:10.1093/mnras/203.1.103. Bibcode: 1983MNRAS.203..103S.
- ↑ 7.00 7.01 7.02 7.03 7.04 7.05 7.06 7.07 7.08 7.09 7.10 Gatewood, George et al. (2001). "Hipparcos and MAP Studies of the Triple Star π Cephei". The Astrophysical Journal 549 (2): 1145–1150. doi:10.1086/319458. Bibcode: 2001ApJ...549.1145G.
- ↑ Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6.
- ↑ 10.0 10.1 10.2 10.3 10.4 Feuillet, Diane K. et al. (2016). "Determining Ages of APOGEE Giants with Known Distances". The Astrophysical Journal 817 (1): 40. doi:10.3847/0004-637X/817/1/40. Bibcode: 2016ApJ...817...40F.
- ↑ "* pi. Cep". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+pi.+Cep.
- ↑ Campbell, William Wallace (1901). "Some recent results secured with the Mills spectrograph". Lick Observatory Bulletin 1 (4): 22–25. doi:10.5479/ADS/bib/1901LicOB.1.22C. Bibcode: 1901LicOB...1...22C.
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