| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Vela |
| Right ascension | 09h 02m 06.860s[1] |
| Declination | −40° 33′ 16.91″[1] |
| Characteristics | |
| Spectral type | B0.5Ib |
| Apparent magnitude (B) | 7.301 |
| Apparent magnitude (V) | 6.926 |
| Apparent magnitude (J) | 5.833±0.020 |
| Apparent magnitude (H) | 5.705±0.034 |
| Apparent magnitude (K) | 5.596±0.024 |
| U−B color index | -0.51[2] |
| B−V color index | 0.50[2] |
| Variable type | Complex |
| Astrometry | |
| Proper motion (μ) | RA: −5.81 mas/yr Dec.: 8.25 mas/yr |
| Distance | 6200±650 ly (1900±200[3] pc) |
| Details | |
| Mass | 1.88 (neutron star), ~18 (supergiant) M☉ |
| Radius | ~11.2 R☉ |
| Luminosity | 112,000 (supergiant) L☉ |
| Temperature | 31,500 (supergiant) K |
| Metallicity | ? |
| Rotation | 8.964 days (supergiant) |
| Age | ? years |
| Other designations | |
| Database references | |
| SIMBAD | data |
Vela X-1 is a pulsing, eclipsing high-mass X-ray binary (HMXB) system, associated with the Uhuru source 4U 0900-40 and the supergiant star HD 77581. The X-ray emission of the neutron star is caused by the capture and accretion of matter from the stellar wind of the supergiant companion. Vela X-1 is the prototypical detached HMXB.[4]
The orbital period of the system is 8.964 days, with the neutron star being eclipsed for about two days of each orbit by HD 77581. The spin period of the neutron star is about 283 seconds, and gives rise to strong X-ray pulsations. The mass of the pulsar is estimated to be at least 1.88±0.13 solar masses.[5]
Characteristics
Long term monitoring of the spin period shows small random increases and decreases over time similar to a random walk.[6] The accreting matter causes the random spin period changes.
See also
- High-mass X-ray binary
- List of X-ray pulsars
- X-ray binary
References
- ^ a b "HD 77581". SIMBAD. Centre de données astronomiques de Strasbourg.
- ^ a b Klare, G.; Neckel, T. (1977). "UBV, Hβ and polarization measurements of 1660 southern OB stars". Astronomy and Astrophysics Supplement. 27: 215. Bibcode:1977A&AS...27..215K.
- ^ Sadakane, K.; et al. (1985). "Ultraviolet spectroscopic observations of HD 77581 (Vela X-1 = 4U 0900-40)". The Astrophysical Journal. 288: 284. Bibcode:1985ApJ...288..284S. doi:10.1086/162791.
- ^ Mauche, C. W.; Liedahl, D. A.; Akiyama, S.; Plewa, T. (2007). "Hydrodynamic and Spectral Simulations of HMXB Winds". Progress of Theoretical Physics Supplement. 169: 196–199. arXiv:0704.0237. Bibcode:2007PThPS.169..196M. doi:10.1143/PTPS.169.196. S2CID 17149878.
- ^ Quaintrell, H.; et al. (2003). "The mass of the neutron star in Vela X-1 and tidally induced non-radial oscillations in GP Vel". Astronomy and Astrophysics. 401: 313–324. arXiv:astro-ph/0301243. Bibcode:2003A&A...401..313Q. doi:10.1051/0004-6361:20030120. S2CID 5602110.
- ^ Bildsten, L.; et al. (1997). "Observations of Accreting Pulsars". The Astrophysical Journal Supplement Series. 113 (2): 367–408. arXiv:astro-ph/9707125. Bibcode:1997ApJS..113..367B. doi:10.1086/313060. S2CID 706199.
External links