Ursa Major Arc : S(II) images

[Stewart John Bean]

Hi,
Following the excellent article by Peter Goodhew in the curent BAA journal I have become interested in this subject.

From what I can research I think that it is likely that the arc is a galactic object, as Peter suggests, that happens to be associated with the M81 group. In particular the twin parallel filaments could be the shock front from old supernova. If so then Peter’s observation of a Ha signal but zero O(III) image, even after 30 hrs of exposure time, supports the supernova shock front conclusion. Detection of S(II) emission would support the “old shock front” theory as it implies a relatively low temperature associated with a dissipating shock front.

Peter’s O(III) image is at 78deg N effectively centred on HD85345.
Is anyone able, and willing, to do some deep imaging in S(II) ?

Stewart Bean

[Author]

Posts