2 Persei


2 Persei is a binary star system in the northern constellation Perseus, located around 500 light years away from the Sun. It is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude is 5.70.[2] The system is moving further away from the Earth with a heliocentric radial velocity of 11 km/s.[4]

2 Persei
Observation data
Epoch J2000      Equinox J2000
Constellation Perseus
Right ascension 01h 52m 09.37243s[1]
Declination +50° 47′ 34.0662″[1]
Apparent magnitude (V) 5.70[2]
Spectral type B9pHgMn[3]
B−V color index −0.067±0.004[2]
Radial velocity (Rv)11.4±0.2[4] km/s
Proper motion (μ) RA: +17.454[1] mas/yr
Dec.: −29.871[1] mas/yr
Parallax (π)6.5107 ± 0.1939 mas[1]
Distance500 ± 10 ly
(154 ± 5 pc)
Absolute magnitude (MV)−0.14[2]
Primary2 Persei A
Companion2 Persei B
Period (P)5.62698±0.00002 d
Eccentricity (e)0.024±0.011
Periastron epoch (T)2440281.3±0.4 JD
Argument of periastron (ω)
Semi-amplitude (K1)
26.5±0.3 km/s
Luminosity145.30[2] L
Temperature9,412[1] K
Rotational velocity (v sin i)25[5] km/s
Other designations
BD+50°379, FK5 1052, HD 11291, HIP 8714, HR 536, SAO 22696[6]
Database references

In 1970 radial velocity measurements from spectrograms taken at David Dunlap Observatory indicated it was a single-lined spectroscopic binary.[7][5] Follow up observations led to the determination that it had a nearly circular orbit with a period of 5.6 days.[4] The visible component is a chemically peculiar mercury-manganese star with a stellar classification of B9pHgMn.[3] Other analyses of its spectrum have assigned it the giant star spectral type of B9III.[8]


  1. ^ a b c d e f Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. ^ a b c d e Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
  3. ^ a b Cowley, A.; et al. (April 1969). "A study of the bright A stars. I. A catalogue of spectral classifications". Astronomical Journal. 74: 375–406. Bibcode:1969AJ.....74..375C. doi:10.1086/110819.
  4. ^ a b c d Heard, J. F.; Krautter, A. (1975). "The orbit of the spectroscopic binary HD 11291". Journal of the Royal Astronomical Society of Canada. 69: 22–24. Bibcode:1975JRASC..69...22H.
  5. ^ a b Abt, Helmut A.; et al. (July 2002). "Rotational Velocities of B Stars". The Astrophysical Journal. 573 (1): 359–365. Bibcode:2002ApJ...573..359A. doi:10.1086/340590.
  6. ^ "2 Per". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-03-19.
  7. ^ Hube, Douglas P. (1970). "The radial velocities of 335 late B-type stars". Memoirs of the Royal Astronomical Society. 72: 233–280. Bibcode:1970MmRAS..72..233H.
  8. ^ Sato, K.; Kuji, S. (November 1990). "MK classification and photometry of stars used for time and latitude observations at Mizusawa and Washington". Astronomy and Astrophysics Supplement Series. 85 (3): 1069–1087. Bibcode:1990A&AS...85.1069S.