If the standard disk instability model for outbursts in dwarf novae (DNe) iscorrect, the disk in quiescence should be cold and optically thick. Butquiescent DNe show UV and optical emission lines. Why? Is the disk opticallythin in the continuum? Does viscous dissipation near the disk photosphereproduce a corona? Or, is a corona created by X-ray illumination of the disk froma hot boundary layer? Here we propose to test the X-ray illumination hypothesiswith simultaneous, highly time-resolved observations of SS Cyg in quiescencewith XMM-Newton and HST/STIS. The X-ray flux in SS Cyg varies on shorttimescales. If X-ray illumination is responsible for the emission lines, theyshould vary in response to the X-ray flux. If not, one of the other mechanisms must be responsible.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2018-11-24T07:23:42Z/2018-11-24T23:52:02Z
Version
19.17_20220121_1250
Mission Description
The European Space Agencys (ESA) X-ray Multi-Mirror Mission (XMM-Newton) was launched by an Ariane 504 on December 10th 1999. XMM-Newton is ESAs second cornerstone of the Horizon 2000 Science Programme. It carries 3 high throughput X-ray telescopes with an unprecedented effective area, and an optical monitor, the first flown on a X-ray observatory. The large collecting area and ability to make long uninterrupted exposures provide highly sensitive observations. Since Earths atmosphere blocks out all X-rays, only a telescope in space can detect and study celestial X-ray sources. The XMM-Newton mission is helping scientists to solve a number of cosmic mysteries, ranging from the enigmatic black holes to the origins of the Universe itself. Observing time on XMM-Newton is being made available to the scientific community, applying for observational periods on a competitive basis.
European Space Agency, Dr Knox Long, 2019, 'Do X-rays Make Disk Emission Lines in Quiescent Dwarf NovaequestionMark', 19.17_20220121_1250, European Space Agency, https://doi.org/10.5270/esa-hwe1ky1
