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Session 65 - New Views of the Magellanic Clouds - II.
Oral session, Wednesday, June 12
Historical Society,
\def\haH\alpha \def\cmsqssr\hboxcm^-2 s^-1 sr^-1 \def\cmcub\hbox\rmcm^-3 \def\lesssim\mathrel\hbox\rlap\hbox\lower4pt\hbox\sim\hbox< \def\cmsixpc\hbox\rmcm^-6 \rmpc
Faint \ha\ emission of EM 0.5 -- 1.0 \cmsixpc\ has been detected from points at the leading edges of the Magellanic Stream clouds MS II, MS III, and MS IV (Weiner amp; Williams 1996, AJ 111, 1156). We present further observations which map \ha\ emission around the nucleus of the cloud MS IV. We find emission of EM 0.1 -- 0.5 \cmsixpc, generally strongest on the leading edge of the cloud as defined by the H \smallI 21-cm contours; a feature in the IRAS 100\mu map also appears to be associated with the leading edge and \ha. This provides further evidence that the \ha\ is generated by ram pressure heating, as the clouds move through tenuous hot coronal gas in the Galactic halo. The unstable interface between the coronal and Stream gas will eventually destroy the MS clouds; much material may already have been stripped out of the Magellanic Clouds and shredded. The gaseous galactic corona likely exerts a considerable influence on both the orbit of the Magellanic Clouds and the evolution of the Clouds' ISM.
