The Structure Of The Accretion Disk In The ADC Source 4U 1822-371

Bayless, A. J.
Robinson, E. L.
Hynes, R. I.
Ashcraft, T. A.
Cornell, M. E.
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The low-mass X-ray binary (LMXB) 4U 1822-371 has an accretion disk corona (ADC) that scatters X-ray photons from the inner disk and neutron star out of the line of sight. It has a high orbital inclination and the secondary star eclipses the disk and ADC. We have obtained new time-resolved UV spectrograms and V- and I-band photometry of 4U 1822-371. The large quadratic term in our new optical eclipse ephemeris confirms that the system has an extremely high rate of mass transfer and mass accretion. The C IV lambda lambda = 1548 - 1550 angstrom emission line has a half width of similar to 4400 km/s, indicating a strong, high velocity wind is being driven off the accretion disk. Near the disk the wind is optically thick in UV, V, and J and the eclipse analysis shows that in V and J the optically thick wind extends nearly to the outer edge of the disk. The ADC must also extend vertically to a height equal to approximately half the disk radius.

Amanda J. Bayless, Edward L. Robinson, Robert I. Hynes, Teresa A. Ashcraft, and Mark E. Cornell. AIP Conference Proceedings 1248, 141 (Jul., 2010); doi: 10.1063/1.3475169