NOAO >   Observing Info >   Approved Programs >   2006A-0372

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Proposal Information for 2006A-0372


PI: Dawn M. Gelino, California Institute of Technology, dawn@ipac.caltech.edu
Address: Michelson Science Center, IPAC, MS 100-22, 770 South Wilson Ave, Pasadena, CA 91125

CoI: Edward Robinson, University of Texas at Austin
CoI: Robert Hynes, Louisiana State University

Title: High Temperature Accretion Flows and Reprocessing in X-Ray Binaries: The ADC Source 4U 1822-371

Abstract: The eclipsing low-mass X-ray binary 4U 1822-371 is the ideal system in which to observe hot accretion and the effects of strong irradiation. Its orbital period is 5.57 hours and its high orbital inclination angle causes the neutron star flux to be blocked by the system's edge-on accretion disk. Accretion Disk Coronas (ADCs) are present in most if not all low-mass X-ray binaries but are usually not visible. However, since the neutron star in this system is hidden, its ADC is visible. 4U 1822-371 provides a unique opportunity to study an ADC and disk irradiation because the eclipse by the secondary star allows their geometry and flux to be mapped. We will perform a multiwavelength light curve synthesis and eclipse analysis of 4U 1822-371. We have been awarded 10 orbits of HST time to obtain time-resolved UV spectral energy distributions, as well as funding for the IR observations proposed for here. The role of the proposed CTIO observations is to provide the IR data needed to disentangle the cooler outer disk contributions from the hotter ADC and inner disk. The J-, H-, and K_s-band light curves obtained over 3 nights with ISPI on the CTIO 4m will be combined with UV data, as well as X-ray and optical data to achieve the scientific goal of mapping the geometry and flux from both the ADC and the irradiated accretion disk in \4u.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2006A-0372

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