Theta Persei
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Perseus |
| Right ascension | 02h 44m 11.98704s |
| Declination | +49° 13′ 42.4111″ |
| Apparent magnitude (V) | 4.11 / 9.987 |
| Characteristics | |
| θ Per A | |
| Evolutionary stage | Main sequence |
| Spectral type | F8 V |
| U−B color index | +0.00 |
| B−V color index | +0.49 |
| θ Per B | |
| Spectral type | M1.5 V |
| B−V color index | +1.48 |
| Astrometry | |
| Radial velocity (Rv) | +24.32 km/s |
| Proper motion (μ) | RA: +334.66 mas/yr Dec.: -89.99 mas/yr |
| Parallax (π) | 89.87±0.22 mas |
| Distance | 36.29 ± 0.09 ly (11.13 ± 0.03 pc) |
| Absolute magnitude (MV) | 3.88 |
| Orbit | |
| Period (P) | 2,720 yr |
| Semi-major axis (a) | 22.289″ |
| Eccentricity (e) | 0.13 |
| Inclination (i) | 75.44° |
| Longitude of the node (Ω) | 128° |
| Periastron epoch (T) | B 1613 |
| Argument of periastron (ω) (secondary) | 100.64° |
| Details | |
| θ Per A | |
| Mass | 1.138±0.010 M☉ |
| Radius | 1.319±0.011 R☉ |
| Luminosity | 2.235±0.040 L☉ |
| Surface gravity (log g) | 4.43±0.17 cgs |
| Temperature | 6,328±86 K |
| Metallicity [Fe/H] | −0.03±0.09 dex |
| Age | 4.0±0.4 Gyr |
| θ Per B | |
| Mass | 0.521±0.052 M☉ |
| Radius | 0.498±0.017 R☉ |
| Temperature | 3,685±60 K |
| Metallicity [Fe/H] | −0.03±0.09 dex |
| Age | 2.4 Gyr |
| Other designations | |
| θ Per, BD+48°746, GJ 107, CCDM J02441+4913, IDS 02374+4848, WDS J02442+4914 | |
| θ Per A: 13 Persei, HR 799, HD 16895, HIP 12777, FK5 93, GC 3277, PPM 45428, SAO 38288 | |
| θ Per B: 2MASS J02441025+4913540 | |
| Database references | |
| SIMBAD | θ Per |
| θ Per A | |
| θ Per B | |
Theta Persei (Theta Per, θ Persei, θ Per) is a star system 37 light years away from Earth, in the constellation Perseus. It is one of the closest naked-eye stars.
The primary star is a yellowish dwarf (main sequence) star of spectral type F8V, which is somewhat larger and brighter than the 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 M1.V, orbiting about 250 AU from the primary. It has a Gaia Data Release 2 parallax of 89.2871±0.1534 mas, corresponding to a distance of 11.2 pc.
An 11th-magnitude star is listed in double-star catalogues as component C of the multiple system. It was 95″ away from component A in 2002, although the separation is rapidly increasing as it is a distant background object with a very different proper motion to the other two stars. An unconfirmed companion, possibly a brown dwarf, was reported 6.2″ from θ Persei B in 2010.