Vela X-1
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| Observation data Epoch J2000.0 (ICRS) |
|
|---|---|
| Constellation (pronunciation) |
Vela |
| Right ascension | 09h 02m 06.860s |
| Declination | -40° 33′ 16.91″ |
| Apparent magnitude (V) | 6.76 to 6.99 (supergiant component) |
| Characteristics | |
| Spectral type | B0.5Ib (supergiant component) |
| U-B color index | -0.51 (supergiant component) |
| B-V color index | 0.50 (supergiant component) |
| Variable type | several causes |
| Astrometry | |
| Proper motion (μ) | RA: −5.81 mas/yr Dec.: 8.25 mas/yr |
| Distance | 6200±650 ly (1900±200 pc) |
| Details | |
| Mass | 1.88 M☉ |
| Radius | ? R☉ |
| Luminosity | ? L☉ |
| Temperature | ? K |
| Metallicity | ? |
| Rotation | 8.964 days |
| Age | ? years |
| Other designations | |
| Data sources: | |
| Hipparcos Catalogue, GCVS (4.2), [1],[2] |
|
Vela X-1 is a high-mass X-ray binary system. It consists of an X-ray pulsar in orbit around a supergiant star. The orbital period of the system is 8.964 days and the neutron star is eclipsed for about 2 days out of each orbit by its companion star. The spin period of the neutron star is about 283 seconds. Long term monitoring of the spin period shows small random increases and decreases over time similar to a random walk.[3] 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. The accreting matter causes the random spin period changes. The mass of the pulsar is estimated to be at least 1.88 solar masses.[4]
[edit] References
- ^ UBV, Hβ and polarization measurements of 1660 southern OB stars, G. Klare and Th. Neckel, Astron. Astrophys., Suppl. Ser. 27 (February 1977), pp. 215–247.
- ^ Ultraviolet spectroscopic observations of HD 77581 (Vela X-1 = 4U 0900-40), K. Sadakane et al., Astrophysical Journal 288 (January 1, 1985), pp. 284–291.
- ^ Observations of Accreting Pulsars, L. Bildsten, et al., 1997, Astrophysical Journal Supplement Series, 113, p. 367.
- ^ The mass of the neutron star in Vela X-1 and tidally induced non-radial oscillations in GP Vel, H. Quaintrell et al., Astronomy and Astrophysics 401 (April 2003), pp. 313–323; also, arXiv:astro-ph/0301243.
[edit] See also
[edit] External links
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