Kiel 2004 – wissenschaftliches Programm

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EP: Extraterrestrische Physik

EP 8: Poster-1

EP 8.2: Poster

Montag, 8. März 2004, 17:45–19:30, Foyer

X-ray spectral studies of the Local Bubble by shadowing the darkest regions in the Milky Way — •Dieter Breitschwerdt^1,2, Michael Freyberg¹, Paulo Mendes¹, and João Alves³ — ¹MPI für extraterrestrische Physik, Garching, Germany — ²Institut für Astronomie, Universität Wien, Austria — ³ESO, Garching, Germany

The origin of the Local Bubble, which together with the Local Cloud hosting the solar system is our cosmic habitat, is still uncertain. Current EUV and X-ray observations favour a multi-supernova origin, with a possible heliospheric contribution from charge exchange reactions with solar wind ions. In order to disentangle the very local, the local and the more distant soft X-ray emission, shadowing experiments towards high column density molecular clouds at different distances and directions have proven to be a very reliable tool. Of particular interest are the highest column density absorbers, such as the Ophiuchus molecular cloud and the Bok globule Barnard 68. We have successfully observed these targets recently with the X-ray observatory XMM-Newton and have obtained both images and spectra. We are now for the first time able to reliably analyze the Local Bubble spectrum between 0.3 − 1.1 keV in these directions, as well as obtaining spectral information on the Loop I superbubble. We show that OVII and OVIII line complexes are present in all local spectra, which is in serious disagreement with the standard model (local plasma at 10⁶ K). In this talk also possible heliospheric contributions to the soft X-ray spectrum will be discussed.