Abstract for Proposal 088487
Accretion physics in AR UMa, an extremely magnetized polar
We propose a triggered observation of the highest magnetized polar,
AR UMa. Our target with a magnetic field of about 230MG gives access
to an as yet unexplored parameter regime of magnetic accretion. It
escaped a high-state X-ray observation so far due to an extended low
state. Utilizing the broad spectral range covered by XMM-Newton including
the OM, we will simultaneously determine the energy content of the main
cooling channels of the accretion plasma: cyclotron radiation in the
UV, plasma radiation in hard X-rays and re-processed radiation in soft
X-rays. We will compare our observations with accretion column models
and study quantitatively the energy balance of the cooling plasma as a
function of the accretion rate and the magnetic field strength.
Details on Observing Strategy and Trigger Criteria
An optical monitoring programme is set up. A high state is indicated
if V<15.8. XMM-Newton observations will triggered if the high state is
stable (brightness above the limit for one week) and shall be performed
within one week after triggering