40 Persei is a wide binary star[13] system in the northern constellation of Perseus. It has the Bayer designation ο Persei, while 40 Persei is the Flamsteed designation. The system is visible to the naked eye as a faint, blue-white hued point of light with an apparent visual magnitude of 4.97.[2] It is located approximately 1060 light years away from the Sun based on parallax,[1] and is drifting further away with a radial velocity of +22 km/s.[6] The system is a member of the Perseus OB2 association of co-moving stars.[14]
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Perseus |
| Right ascension | 03h 42m 22.64555s[1] |
| Declination | 33° 57′ 54.0893″[1] |
| Apparent magnitude (V) | 4.97[2] |
| Characteristics | |
| Spectral type | B0.5V[3] + A1Vn[4] |
| U−B color index | −0.84[5] |
| B−V color index | +0.00[5] |
| Astrometry | |
| Radial velocity (Rv) | +22.00[6] km/s |
| Proper motion (μ) | RA: +2.71[1] mas/yr Dec.: −5.91[1] mas/yr |
| Parallax (π) | 3.09 ± 0.21 mas[1] |
| Distance | 1,060 ± 70 ly (320 ± 20 pc) |
| Absolute magnitude (MV) | −2.26[2] |
| Details | |
| 40 Per A | |
| Mass | 12.5[7] M☉ |
| Luminosity | 936[2] L☉ |
| Surface gravity (log g) | 4.36[8] cgs |
| Temperature | 29,330[9] K |
| Metallicity [Fe/H] | −0.43[2] dex |
| Rotational velocity (v sin i) | 10[10] km/s |
| Age | 7.2[11] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The primary component is a massive B-type main-sequence star with a stellar classification of B0.5V.[3] It is about 7.2[11] million years old and has a very low projected rotational velocity for an early B-type star,[15] measured at 10 km/s.[10] This star has 12.5[7] times the mass of the Sun and is radiating 936[2] times the Sun's luminosity from its photosphere at an effective temperature of 29,330 K.[9] The companion is magnitude 10.04, A-type main-sequence star with a class of A1Vn, and is located at an angular separation of 19.8″ from the primary.[4]