|Title||Unexplained Hard X-ray Emission from Hot Single White Dwarfs|
|Author||Prof You-Hua Chu|
|Description||The central star of the Helix Nebula, WD2226-210, is a hot white dwarf (WD). Its X-ray emission has a soft photospheric component and a harder component peaking near 1 keV, which cannot be explained, as it does not have a binary companion or fast stellar wind. Only one other single WD, KPD0005+5106, shows similar X-ray characteristics unambiguously, while two PG1159-type WDs have tentative detections of hard X-rays. We request 300 ks XMM observations of WD2226, using RGS spectra to determine the temperature, abundances, and ionization equilibrium of the X-ray-emitting plasma, and using EPIC data to study the temporal variations of the 1 keV emission. We also request short observations of the other three WDs to characterize their hard X-ray emission, and assess its physical implications.|
|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, 2014-01-19T00:00:00Z, 069305, 17.56_20190403_1200. https://doi.org/10.5270/esa-fky7p29|