VELA X-1: how to produce asymmetric eclipses.

Details VELA X-1: how to produce asymmetric eclipses. VELA X-1: how to produce asymmetric eclipses.

Jul 1996

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996a%26a...311..793f&link_type=abstract

Astronomy and Astrophysics, v.311, p.793-802

Astronomy and Astrophysics

Astrophysics

11

Hydrodynamics, Binaries: Eclipsing, Stars: Mass-Loss, Stars: Neutron, X-Rays: Stars, Stars: Vela X-1

Scientific paper

Light curves of the X-ray pulsar Vela X-1 obtained with the ASCA satellite show a strong asymmetry in the hard energy band during the eclipse of the X-ray source: a steep drop at ingress is followed by a gradual decline, whereas only a steep increase is observed at egress. X-ray scattering off the dense accretion wake trailing the neutron star cannot explain the gradual decline because of the long persistence of the latter ({DELTA}φ=0.11). Instead we propose that scattering in an extended photoionization wake is responsible. This wake is caused by the switch-off of the radiative force that drives the B supergiant wind during the passage through the highly ionized Stroemgren region surrounding the X-ray source. The stalled gas then trails the neutron star, which moves relative to the B star surface (no corotation). A model for the Vela X-1 system which assumes that the B star does not rotate gives too large a phase extent for the dense wake and can be ruled out. Including the B star rotation in an approximate way, the relative azimuthal motion of the neutron star is slower and the wake covers a smaller phase interval. Finally, we assume that the Stroemgren sphere does not reach too deep into the wind accelerating region. The wind can then reach a certain fraction of the terminal velocity before the radiative force is switched off. This elongates the photoionization wake further and both its phase extent and its scattering efficiency match the observations.

Affiliated with

Also associated with

No associations

Rating

VELA X-1: how to produce asymmetric eclipses. does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with VELA X-1: how to produce asymmetric eclipses., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and VELA X-1: how to produce asymmetric eclipses. will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1114813