B supergiants display a discontinuous drop in X-ray emission along a dividingline in the H-R diagram (analogous to the one for K giants) which is referred toas the bistability jump at spectral type B1. Our XMM study of the X-rayproperties on both sides of the jump have revealed several interesting results,but some uncertainties have arisen since B supergiant winds are thick to softX-rays, and these winds are thought to be clumpy. We now have observationalevidence that the bistabilty jump extends to the lower luminosity B giants whichhave lower wind densities. Hence, they do not have the problems that areassociated with B supergiants. Therefore we are requesting XMM EPIC observationsof 5 B giants to broaden our understanding of the B star dividing line.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2008-03-06T15:51:03Z/2008-03-12T22:06:49Z
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, Dr Wayne Waldron, 2009, 'A Study of the Discontinuous Drop in X-ray Emission at Spectral Type B1', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-or3081d
