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 clearlyrelated to the bi-stability jump (BSJ) at spectral type B1. Our study revealedseveral interesting and unexpected results, but some uncertainties have arisensince B supergiant winds are thick to soft X-rays. We now have observationalevidence that the BSJ extends to the lower luminosity B giants which have lowerwind densities, i.e., they do not have the B supergiant X-ray optical depthproblem. We are requesting XMM-Newton EPIC observations of 2 B giants tocomplement our 2 AO-6 B giant observations which will enhance our understandingof this B-star dividing line.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2010-03-14T13:16:18Z/2010-03-14T22:39:15Z
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, 2011, 'The Discontinuous Drop in B Giant X-ray Emission at Spectra Type B1', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-wkq5op0
