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Röntgenastronomie stellarer Atmosphären

English title X-ray astronomy of stellar atmospheres
Applicant Güdel Manuel
Number 109255
Funding scheme Project funding (Div. I-III)
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Astronomy, Astrophysics and Space Sciences
Start/End 01.01.2006 - 31.12.2006
Approved amount 44'460.00
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Keywords (8)

stellar astrophysics; x-ray astronomy; coronae; star formation; magnetic fields; X-ray spectroscopy; Stellar coronae; stellar evolution

Lay Summary (English)

Lead
Lay summary
One of the principal findings of previous X-ray missions is the now well-accepted notion that almost every star is a source of atmospheric heating of plasma to some 1-100 Million K (MK). The problem of heating and structuring of outer stellar atmospheres is largely unresolved, and constitutes one of the major riddles in astrophysics. The Sun has in almost all cases served as the benchmark system, often in a two-way process: stellar observations are gauged by the solar analogy, extending the parameter space available from the Sun considerably, and solar physics is generalized by including knowledge we gain from stars. The methodology of this solar-stellar connection'' theme has worked surprisingly well, but has probably been stretched beyond its limits.
The present project addresses the physics of coronae of magnetically very active systems and probes the limitations of the solar analogy. In particular, it addresses the following problem areas:
i) Anomalous'' elemental compositions of stellar coronae will be systematically investigated; what is the dependence between coronal element abundances and the overall magnetic activity level?
ii) Flares produce high coronal densities, but such densities are also found in quiescence. Is there any physical dependence? Are statistical flares responsible for what we record as a steady corona?
iii) Very young objects maintain extremely luminous coronae - is it their accretion disks that are relevant for the enhanced energy release? How does a corona change in the course of its evolution?
iv) Flares accelerate particles that are suggested to heat plasma. Some recent observations are at variance with this expectation. Are there alternative models that apply?

Most of the data used for this project have been recorded by ESA's XMM-Newton X-ray observatory to which PSI has contributed instrumentation. In particular, a large, international project led by PSI, the "XMM-Newton Extended Survey of the Taurus Molecular Coud", provides the basis for X-ray studies of young, forming stars.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

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Associated projects

Number Title Start Funding scheme
66875 Röntgenastronomie stellarer Atmosphären 01.01.2003 Project funding (Div. I-III)

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