Vela X-1

Vela X-1

Starbox begin
name=Vela X-1Starbox observe
epoch=J2000.0 (ICRS)
constell=Vela
ra=RA|09|02|06.860
dec=DEC|-40|33|16.91
appmag_v=6.76 to 6.99
(supergiant component)Starbox character
class=B0.5Ib
(supergiant component)
b-v=0.50
(supergiant component)
u-b=-0.51
(supergiant component)
variable="several causes"Starbox astrometry
prop_mo_ra=−5.81
prop_mo_dec=8.25
dist_ly=6200±650
dist_pc=1900±200Starbox detail
mass=1.88
radius=?
luminosity=?
temperature=?
metal=?
rotation=8.964 days
age=? Starbox catalog
names="Supergiant component:" GP Vel, HD 77581, SAO 220767, HIP 44368, CPD-40°3072, CD-40°4838; "X-ray component:" 1XRS 09002-403, 1RXS J090207.0-403311, 4U 0900-40

Vela X-1 is a high-mass X-ray binary system, associated with the Uhuru source 4U 0900-40.

Chacteristics

Vela X-1 consists of an accreting X-ray pulsar in orbit around HD 77581, a supergiant star. The orbital period of the system is 8.964 days and the neutron star is eclipsed for about two days of each orbit by HD 77581. 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. [ [http://adsabs.harvard.edu/abs/1997ApJS..113..367B Observations of Accreting Pulsars] , L. Bildsten, et al., 1997, Astrophysical Journal Supplement Series, 113, p. 367.] 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. [ [http://adsabs.harvard.edu/abs/2003A&A...401..313Q 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, [http://arxiv.org/abs/astro-ph/0301243 arXiv:astro-ph/0301243] .]

Note

Vela X-1 should not be confused with the isolated radio pulsar, Vela X, which is a very different kind of object. Vela X is associated with a very strong 100 MeV gamma-ray source, and with the rather weak Uhuru X-ray source, 4U 0833-45.

References

See also

* High-mass X-ray binary
* List of X-ray pulsars
* X-ray binary

External links

* [http://f64.nsstc.nasa.gov/batse/pulsar/data/sources/velax1.html Spin frequency history of Vela X-1]


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