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Session 79 - CVs and Novae.
Display session, Wednesday, January 17
North Banquet Hall, Convention Center
We observed the intermediate polar EX Hya with the Hopkins Ultraviolet Telescope during the Astro-2 shuttle mission in 1995 March. The observation provides good signal to noise spectra on time scales of the order of 1 minute of the spectral region from the Lyman Limit to 1860 Å\ with a resolution of about 3 ÅThe total observation time was 32 minutes, and covers phase \phi_67 = 0.94 to 0.39 of the 67 minute white dwarf rotational period. At \phi_67 = 0.0, the spectrum shows strong emission by C \smallIV \lambda1549, C \smallIII \lambda977, \lambda1176, N \small V \lambda1240, Si \small IV \lambda1394, and a blend of lines including Ly \beta. The observed FWHM of the lines is about 2400 km s^-1, and decreases with phase. Weaker emission from C \smallII \lambda1335, He \smallII \lambda1640, and a blend of lines from 916-960 Å\ is also apparent. As the phase increases to 0.39, the average continuum level decreases by about 20%, while the line emission decreases by more than a factor of 4. The profile of the C \small IV \lambda1549 line changes considerably over the course of the observation, with a strong absorption appearing on the blue wing of the line from \phi_67 = 0.25 to the end of the observation. The ratios C \small IV/N \small V and C \small IV/C \small III do not show any significant trend with phase. We also see fluctuations in the continuum flux of \pm 30% on timescales of about 2 minutes during the second half of the observation.
This work was supported by NASA contract NAS 5-27000 to the Johns Hopkins University.
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