Sigma Persei
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Perseus |
| Right ascension | 03h 30m 34.48537s |
| Declination | +47° 59′ 42.7789″ |
| Apparent magnitude (V) | 4.36 |
| Characteristics | |
| Evolutionary stage | horizontal branch |
| Spectral type | K3III |
| U−B color index | +1.54 |
| B−V color index | +1.35 |
| Astrometry | |
| Radial velocity (Rv) | +14.32±0.15 km/s |
| Proper motion (μ) | RA: +3.954 mas/yr Dec.: +18.968 mas/yr |
| Parallax (π) | 9.5060±0.2003 mas |
| Distance | 343 ± 7 ly (105 ± 2 pc) |
| Absolute magnitude (MV) | −0.85 |
| Details | |
| Mass | 1.32 M☉ |
| Radius | 36.89 R☉ |
| Luminosity | 368 L☉ |
| Surface gravity (log g) | 1.46 cgs |
| Temperature | 4,165 K |
| Metallicity [Fe/H] | −0.20 dex |
| Rotational velocity (v sin i) | 2.2 km/s |
| Other designations | |
| σ Per, 35 Per, NSV 1167, BD+47 843, FK5 124, GC 4158, HD 21552, HIP 16335, HR 1052, SAO 38890, PPM 46257 | |
| Database references | |
| SIMBAD | data |
Sigma Persei (Sigma Per, σ Persei, σ Per) is an orange K-type giant star with an apparent magnitude of +4.36. It is approximately 343 light-years from Earth.
Sigma Persei is moving through the Galaxy at a speed of 17.4 km/s relative to the Sun. Its projected Galactic orbit carries it between 24,400 and 43,600 light years from the center of the Galaxy. It came closest to the Sun 5.1 million years ago when it had brightened to magnitude 3.11 from a distance of 202 light years.
In 2014 a planet was reported, Sigma Persei b, with a period of 580 days and a mass approximately 6.5 times that of Jupiter. However, a 2025 study found that the observed radial velocity variations are intrinsic to the star, and not caused by a planetary companion.