Theta Persei

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Theta Persei A/B
Perseus constellation map visualization.PNG
Stars of Perseus
Observation data
Epoch J2000      Equinox J2000
Constellation Perseus
Right ascension 02h 44m 11.98704s[1]
Declination +49° 13′ 42.4111″[1]
Apparent magnitude (V) 4.12/10
Spectral type F7 V + M1 V
U−B color index 0/0.99
B−V color index 0.49/1.48
Radial velocity (Rv) +24.32[2] km/s
Proper motion (μ) RA: +334.66[1] mas/yr
Dec.: -89.99[1] mas/yr
Parallax (π) 89.87 ± 0.22 mas
Distance 36.29 ± 0.09 ly
(11.13 ± 0.03 pc)
Absolute magnitude (MV) 3.89/9.8
Companion Theta Persei B
Period (P) 2720 yr
Semi-major axis (a) 22.29"
Eccentricity (e) 0.13
Inclination (i) 75.44°
Longitude of the node (Ω) 128°
θ Per A
Mass 1.138 ± 0.010[3] M
Radius 1.319 ± 0.011[3] R
Luminosity 2.235 ± 0.040[3] L
Temperature 6,157 ± 37[3] K
Age 4.0 ± 0.4[3] Gyr
Other designations
θ Persei, θ Per, Theta Per, 13 Persei, BD+48°746, CCDM J02441+4913A, FK5 93, GC 3277, HD 16895, HIP 12777, HR 799, IDS 02374+4848 A, PPM 45428, SAO 38288, WDS J02442+4914A

Theta Persei (Theta Per, θ Persei, θ Per) is a star system 37 light years away from Earth, in the constellation Perseus. The primary star is a yellowish dwarf (main sequence) star of spectral type F7V, which is somewhat larger and brighter than our sun, but still within the range considered to have the potential for Earth-like planets. There is also a red dwarf companion of spectral type M1V, orbiting about 250 AU from the primary. The star's age is estimated to be 2.8 billion years but is certainly no less than 1.7 billion years and no greater than 3.9 billion years.[4]

Theta Persei is moving through the Galaxy at a speed of 30.5 km/s relative to the Sun. Its projected Galactic orbit carries it between 23,700 and 34,200 light years from the center of the Galaxy.[4]

Theta Persei came closest to the Sun 285,000 years ago when it had brightened to magnitude 2.99 from a distance of 21.7 light years.[4]


  1. ^ a b c d 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. 
  2. ^ Nidever, David L.; et al. (August 2002), "Radial Velocities for 889 Late-Type Stars", The Astrophysical Journal Supplement Series 141 (2): 503–522, arXiv:astro-ph/0112477, Bibcode:2002ApJS..141..503N, doi:10.1086/340570. 
  3. ^ a b c d e Boyajian, Tabetha S.; et al. (February 2012), "Stellar Diameters and Temperatures. I. Main-sequence A, F, and G Stars", The Astrophysical Journal 746 (1): 101, arXiv:1112.3316, Bibcode:2012ApJ...746..101B, doi:10.1088/0004-637X/746/1/101 . See Table 10, 12.
  4. ^ a b c Theta Persei (HIP 12777)

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