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A. M. N. Ferguson (Kapteyn Institute, Groningen)
The disk-halo interface of galaxies is where the global effects of stellar feedback on the interstellar medium are expected to be the most profound. Popular theories invoke feedback from correlated supernova explosions as a means to create low-density pathways -- ``galactic chimneys" -- through which gas and energy can be funnelled from the disk to the halo. An open question regards the fate of the gas injected into galactic halos by this process. Does it escape or does it simply cool and rain back down on the disk? Can it linger for long enough in the halo to fuel in situ massive star formation? I will present HST/WFPC2 observations of the nearby SBm galaxy NGC55 which reveal the presence of an extraplanar star formation site associated with a galactic chimney. I will discuss whether such events are likely to contribute significantly to the field stellar population in the disk-halo interface of NGC55 and speculate on whether similar processes could have occurred in the Milky Way and more distant spirals.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.