Phi Persei

Phi Persei (Phi Per, φ Persei, φ Per) is a Class B2Vpe, fourth-magnitude star in the constellation Perseus. Phi Persei is binary consisting of a blue main sequence primary of class B2 and an apparent magnitude of 4.01 and a hot subdwarf secondary. Due to its rapid rotation, the primary has a polar radius about 5.5 R☉ and an equatorial radius of about 8.0 R☉. Phi Persei is also a variable star with rapid variations in its brightness and spectrum. The Phi Persei stellar system is located about 716 light-years from Earth.

φ Persei
Location of φ Persei (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Perseus
Right ascension  01h 43m 39.63792s[1]
Declination 50° 41′ 19.4328″[1]
Apparent magnitude (V) 4.06[2] (3.96 - 4.11[3])
Characteristics
Spectral type B2Vep[4]
U−B color index -0.92[2]
B−V color index -0.04[2]
Variable type γ Cas[3]
Astrometry
Radial velocity (Rv)+0.80[5] km/s
Proper motion (μ) RA: +24.59[1] mas/yr
Dec.: -14.01[1] mas/yr
Parallax (π)4.54 ± 0.20[1] mas
Distance720 ± 30 ly
(220 ± 10 pc)
Absolute magnitude (MV)−3.11[6]
Orbit[6][7]
Period (P)126.6731 days
Semi-major axis (a)5.89 mas
Inclination (i)77.6°
Longitude of the node (Ω)295.7°
Periastron epoch (T)2456110.03
Semi-amplitude (K1)
(primary)		9.97 km/s
Semi-amplitude (K2)
(secondary)		81.3 km/s
Details
A
Mass10.1[8] M☉
Radius5.5 - 8.0[6] R☉
Luminosity41,783[9] L☉
Surface gravity (log g)4.46[9] cgs
Temperature32,090[9] K
Rotational velocity (v sin i)440[9] km/s
B
Mass1.14[10] M☉
Radius1.3[10] R☉
Surface gravity (log g)4.2[6] cgs
Temperature53,000[10] K
Age21.5[8] Myr
Other designations
φ Persei, φ Per, Phi Per, BD+49°444, FK5 57, GC 2102, HD 10516, HIP 8068, HR 496, PPM 26670, SAO 22554
Database references
SIMBADdata
φ Persei in optical light

Naming

Flamsteed followed Ptolemy in treating φ Persei as being in Andromeda and gave it the designation 54 Andromedae. It is isolated from the main stars of Perseus, but lies within its formal borders.[11]

In Chinese, 天大將軍 (Tiān Dà Jiāng Jūn), meaning Heaven's Great General, refers to an asterism consisting of φ Persei, γ Andromedae, 51 Andromedae, 49 Andromedae, χ Andromedae, υ Andromedae, τ Andromedae, 56 Andromedae, β Trianguli, γ Trianguli and δ Trianguli. Consequently, the Chinese name for φ Persei itself is 天大將軍二 (Tiān Dà Jiāng Jūn èr, English: the Second Star of Heaven's Great General.).[12]

gollark: I made a simulator for it one time.
gollark: It's not complicated, exactly, just weird.
gollark: N-body gravity is *weird*.
gollark: You *have* read the date on that, right?
gollark: It was inspired by https://www.ietf.org/rfc/rfc3514.txt. It sounded like that would improve security a lot, so this ought to make remote code execution over rednet safe and secure for all.

References
  1. 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
  2. Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  3. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....1.2025S.
  4. Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H.
  5. Wilson, R. E. (1953). "General Catalogue of Stellar Radial Velocities". Carnegie Institute Washington D.c. Publication. Carnegie Institution for Science. Bibcode:1953GCRV..C......0W. LCCN 54001336.
  6. Gies, Douglas R.; Bagnuolo, William G.; Ferrara, Elizabeth C.; Kaye, Anthony B.; Thaller, Michelle L.; Penny, Laura R.; Peters, Geraldine J. (1998). "Hubble Space Telescope Goddard High Resolution Spectrograph Observations of the Be + sdO Binary φ Persei". The Astrophysical Journal. 493 (1): 440–450. Bibcode:1998ApJ...493..440G. doi:10.1086/305113.
  7. "Sixth Catalog of Orbits of Visual Binary Stars". Retrieved 29 December 2016.
  8. Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (2011). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. Vizier catalog entry
  9. Zorec, J.; Frémat, Y.; Domiciano De Souza, A.; Royer, F.; Cidale, L.; Hubert, A.-M.; Semaan, T.; Martayan, C.; Cochetti, Y. R.; Arias, M. L.; Aidelman, Y.; Stee, P. (2017). "Critical study of the distribution of rotational velocities of Be stars". Astronomy & Astrophysics. 595: A132. arXiv:1702.07684. Bibcode:2016A&A...595A.132Z. doi:10.1051/0004-6361/201628760.
  10. Krtička, J.; Kubát, J.; Krtičková, I. (2016). "Stellar wind models of subluminous hot stars". Astronomy & Astrophysics. 593: A101. arXiv:1607.04445. Bibcode:2016A&A...593A.101K. doi:10.1051/0004-6361/201628433.
  11. Wagman, M. (August 1987). "Flamsteed's Missing Stars". Journal for the History of Astronomy. 18 (3): 212. Bibcode:1987JHA....18..209W. doi:10.1177/002182868701800305.
  12. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 10 日
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