X-RAY PHOTOIONIZED BUBBLE IN THE WIND OF VELA X-1 PULSAR SUPERGIANT COMPANION

Journal Article · Mon Oct 01 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/757/2/162· OSTI ID:22092167

Krticka, Jiri; Skalicky, Jan ^[1]; Kubat, Jiri ^[2]

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1. Ustav teoreticke fyziky a astrofyziky, Masarykova univerzita, Kotlarska 2, CZ-611 37 Brno (Czech Republic)
2. Astromomicky ustav Akademie ved Ceske republiky, Fricova 298, CZ-251 65 Ondrejov (Czech Republic)

Vela X-1 is the archetype of high-mass X-ray binaries (HMXBs), composed of a neutron star and a massive B supergiant. The supergiant is a source of a strong radiatively driven stellar wind. The neutron star sweeps up this wind and creates a huge amount of X-rays as a result of energy release during the process of wind accretion. Here, we provide detailed NLTE models of the Vela X-1 envelope. We study how the X-rays photoionize the wind and destroy the ions responsible for the wind acceleration. The resulting decrease of the radiative force explains the observed reduction of the wind terminal velocity in a direction to the neutron star. The X-rays create a distinct photoionized region around the neutron star filled with a stagnating flow. The existence of such photoionized bubbles is a general property of HMXBs. We unveil a new principle governing these complex objects, according to which there is an upper limit to the X-ray luminosity the compact star can have without suspending the wind due to inefficient line driving.

• OSTI ID: 22092167
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 757; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCELERATION
ASTRONOMY
ASTROPHYSICS
BINARY STARS
HYDRODYNAMICS
LUMINOSITY
MASS
NEUTRON STARS
PHOTOIONIZATION
PULSARS
STAR ACCRETION
STELLAR WINDS
VELOCITY
X RADIATION