|Title||Understanding the on-off states in CAL 83|
|Author||Dr Robert Schwarz|
|Description||CAL 83 is the canonical close-binary supersoft X-ray source and also among the two rare systems to show repeated on-off X-ray states. These systematic changes are anti-correlated with the optical brightness and closely connected to processes occuring at near Eddington accretion rates. We propose an optically triggered XMM monitoring of CAL 83 through one X-ray bright state following its evolution with many short pointings (5 ksec each). This will provide new insight into the yet unknown physical mechanism behind the X-ray on-off states by testing three alternatives: (a) Luminosity changes at constant temperature that indicate a cessation of the shell burning; (b) Temperature changes due to variations of the effective radius of the white dwarf; (c) Absorption, e.g. by a variable wind.|
|Publication||No observations found associated with the current proposal|
|Instrument||EMOS1, EMOS2, EPN, OM, RGS1, RGS2|
|Mission Description||The European Space Agency's (ESA) X-ray Multi-Mirror Mission (XMM-Newton) was launched by an Ariane 504 on December 10th 1999. XMM-Newton is ESA's 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 Earth's 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.
|Publisher And Registrant||European Space Agency|
|Credit Guidelines||European Space Agency, 2010-06-23T00:00:00Z, 050653, 17.56_20190403_1200. https://doi.org/10.5270/esa-m024vk0|