Subaru Seminars



This Month






Site Map

The Subaru Seminar is usually held in Room 104 of the Hilo Base Facility, adjacent to the main lobby. Everyone is welcome to attend. If you are interested in giving a seminar, please contact Subaru seminar organizers (Tomonori Usuda, Kumiko S. Usuda, Masahiko Hayashi, Masayuki Akiyama) by email.

July 22, Friday at 11:00am

" Emission-Line Eclipse Mapping of Accretion Disks in CVs;

Ryoko Ishioka (SUBARU Telescope)

Cataclysmic variables are close binaries with a white dwarf primary and a low-mass main-sequence companion that transfers mass onto the white dwarf through Roche-lobe overflow. In the case that the magnetic field of the WD is weak enough, the gas accreted onto the WD forms an accretion disk.
Two methods are used to reconstruct the structure of the disk. One is the eclipse mapping, a reconstruction technique using an eclipse of the high inclination binary systems. We can reconstruct two-dimensional (2D) brightness distribution from one-dimensional eclipse light curves based on the maximum entropy. Another useful method is the Doppler tomography, an imaging technique to map the line emissivity in 2D velocity space. This method, however, provides no definite information in position space. In other words, we need to assume a model relating the position space to the velocity place if we want to convert the velocities measured in a Doppler map to positions.
I will present a new method, by combining the above two methods, to map the velocity fields in position space over the disk plane. In this method, we need a set of high time-, and wavelenth-resolved spectra over an orbit of an eclipsed binary. The emission-line profiles are devided into dozens of sections with a constant wavelength interval. For each section, an eclipse light curve is constructed. We make an eclipse map using the eclipse mapping for each of calculated light curves with different wavelengths. Then we can get a map of the velocity fields.

Seminars are also held at JAC, CFHT, and IfA.

Copyright (c) 1999-2000 Subaru Telescope, NAOJ. All rights reserved.