|Title||X-ray spectroscopy of H1504+65, an extremely hot bare stellar core|
|Author||Prof Klaus Werner|
|Description||H1504+65 is the hottest known white dwarf (Teff=200,000 K). Its photosphere is mainly composed of carbon and oxygen, hence this unique white dwarf resembles the bare stellar core of a former red giant. Because of its high effective temperature H1504+65 is the only star at all which shows a photospheric absorption line spectrum in the soft X-ray region. We have analysed a Chandra spectrum and identified a wealth of spectral lines from highly ionized O, Ne, and Mg. We also detect nickel lines but, surprisingly, fail to detect iron. The reduced iron opacity allows thermal radiation to escape from deep hot layers. Our models predict that XMM-Newton could for the first time acquire a stellar photospheric spectrum in the 10-30 Angstroem (1.2-0.4 KeV) region. This enables a precise temperature determination.|
|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, 2006-10-18T00:00:00Z, 030101, 17.56_20190403_1200. https://doi.org/10.5270/esa-1l21nv0|