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.
Quick Facts Observation data Epoch J2000 Equinox J2000, Constellation ...
θ Persei
Location of θ Persei (circled) |
Observation data
Epoch J2000 Equinox J2000 |
| Constellation |
Perseus |
|
| Right ascension |
02h 44m 11.98704s[1] |
| Declination |
+49° 13′ 42.4111″[1] |
| Apparent magnitude (V) |
4.11[2] / 9.987[3] |
| Characteristics |
| θ Per A |
| Evolutionary stage |
Main sequence |
| Spectral type |
F8 V[4] |
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| U−B color index |
+0.00[5] |
| B−V color index |
+0.49[5] |
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| θ Per B |
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| Spectral type |
M1.5 V[6] |
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| B−V color index |
+1.48[7] |
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| Astrometry |
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| Radial velocity (Rv) | +24.32[8] km/s |
| Proper motion (μ) | RA: +334.66[1] mas/yr
Dec.: -89.99[1] mas/yr |
| Parallax (π) | 89.87±0.22 mas[1] |
| Distance | 36.29 ± 0.09 ly
(11.13 ± 0.03 pc) |
| Absolute magnitude (MV) | 3.88[9] |
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| Orbit[10] |
|---|
| 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[11] M☉ |
| Radius | 1.319±0.011[11] R☉ |
| Luminosity | 2.235±0.040[11] L☉ |
| Surface gravity (log g) | 4.43±0.17[12] cgs |
| Temperature | 6,328±86[12] K |
| Metallicity [Fe/H] | −0.03±0.09[12] dex |
| Age | 4.0±0.4[11] Gyr |
| θ Per B |
|---|
| Mass | 0.521±0.052[3] M☉ |
| Radius | 0.498±0.017[3] R☉ |
| Temperature | 3,685±60[3] K |
| Metallicity [Fe/H] | −0.03±0.09[12] dex |
| Age | 2.4[3] 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 |
Close
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.[13]
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,[14] although the separation is rapidly increasing as it is a distant background object with a very different proper motion to the other two stars.[15] An unconfirmed companion, possibly a brown dwarf, was reported 6.2″ from θ Persei B in 2010.[16]
