X Persei
 Location of X Per (circled) |
|
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Perseus |
| Right ascension | 03h 55m 23.07715s |
| Declination | +31° 02′ 450062″ |
| Apparent magnitude (V) | 6.778(6.03 - 7.00) |
| Characteristics | |
| Spectral type | O9.5IIIe-B0Ve |
| U−B color index | −0.790 |
| B−V color index | +0.137 |
| Variable type | γ Cas + X-ray pulsar |
| Astrometry | |
| Radial velocity (Rv) | −50.00 km/s |
| Proper motion (μ) |
RA: −2.28 mas/yr Dec.: −5.42 mas/yr |
| Parallax (π) | 2.34 ± 0.70mas |
| Distance | 950pc |
| Absolute magnitude (MV) | −3.47 |
| Orbit | |
| Primary | X Per |
| Companion | 4U 0352+309 |
| Period (P) | 250.3 days |
| Semi-major axis (a) | 2.2 AU |
| Eccentricity (e) | 0.111 |
| Inclination (i) | 23 - 30° |
| Details | |
| Mass | 15.5 M☉ |
| Radius | 6.5 R☉ |
| Luminosity | 29,000 L☉ |
| Surface gravity (log g) | 4.0 cgs |
| Temperature | 29,500 K |
| Rotational velocity (v sin i) | 215 km/s |
| Age | 5 Myr |
| Other designations | |
| A: X Per | |
| B: 4U 0352+309 | |
| Database references | |
| SIMBAD | data |
X Persei is a binary star system located in the constellation Perseus, approximately 950 parsecs away.
The optical star X Persei has been classified either as an O-type giant or a B-type main sequence star. It is a Be star, rotating rapidly, and at times surrounded by a disk of expelled material. This qualifies it as a Gamma Cassiopeia variable, and the visual range is magnitude 6 - 7. There is a faint optical companion separated by 22.5" which the Catalog of Components of Double and Multiple Stars refers to as X Persei B.
X Persei A is in orbit with a neutron star, which is catalogued as 4U 0352+309 in the final Uhuru catalog of X-ray objects. It is a pulsar with an unusually long period of 837 seconds.
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