Radiation-driven winds are a common feature of hot stars, not only for massivestars but also for low-mass stars, which display weak winds. Massive stars arewell known X-ray sources, in which the observed X-ray emission is attributed toturbulence and shocks in the strong winds. Although the winds of low-mass starsare significantly weaker, turbulence and shocks could be present also in thiscase and produce X-ray emission. Recently this was confirmed for two low-massextreme He stars, BD+37 442 and BD+37 1977: in both cases the spectralproperties are similar to those observed in massive stars. Now we propose toobserve with XMM also other extreme He stars, which, although are characterizedby rather different physical properties, have radiation-driven winds comparable to that of the previous sdO stars.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2016-09-18T15:09:20Z/2016-09-19T05:29:20Z
Version
17.56_20190403_1200
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, Mr Nicola La Palombara, 2017, 'X-ray emission of extreme He stars', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-ir3aucm
