HST spectrally-resolved accretion disk maps of UX UMa in the ultraviolet
Abstract
We present spectrally-resolved eclipse maps of the UX UMa accretion disk in the spectral region 1170--2400 Angstroms. The analysis is based on low-dispersion time-resolved spectroscopy during eclipse, obtained with the HST Faint Object Spectrograph. The out-of-eclipse spectra show prominent emission lines (CIII lambda 1176, Lyalpha , NV lambda 1240, SiIV lambda 1400, CIV lambda 1550) as well as many absorption features and possibly a broad absorption band centered at about 1900 Angstroms. HeII lambda 1640 appears as a weak emission line. At mid-eclipse the continuum flux is reduced by a factor ~ 3, while the emission lines are much less affected by the eclipse and some of the lines that are seen in absorption in the out-of-eclipse spectra appear in emission. UV continuum light curves show significant flickering activity outside of eclipse, relatively much stronger than observed in the optical range. The eclipses are deep and steep in the continuum with an asymmetry in their egress portion, however no clear evidence of a compact bright spot is seen. The spectra were divided into passbands ( ~ 40 Angstroms in the continuum and ~ 3000 Km/s in the emission lines) and light curves were extracted for each one. Maximum-entropy eclipse mapping techniques were used to solve for a map of the disk brightness distribution and for the flux of an additional uneclipsed component in each band. Radial brightness temperature profiles and spatially-resolved disk spectra derived from these maps are presented and discussed.
- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1994
- Bibcode:
- 1994AAS...18511605B