Session 10 - Spiral Galaxies.
Display session, Monday, June 10
Great Hall,

## [10.10] The Ionized Gas and Radio Halo of NGC 3432 (ARP 206)

J. English, J. Irwin (Queen's Univ.)

NGC 3432 appears to provide a counter-example to the notion that high latitude H\alpha emission, either in the form of an extended diffuse layer (DIG) or in discrete features, correlates with the existance of a strong non-thermal radio contiuum halo. VLA data displays a radio halo extending up to 5.3 kpc above the plane as well as radio spurs''. These latter features do not appear, in general, to align with regions of star formation in the disk nor with discrete ionized features. If this near edge-on galaxy had a DIG component similar to that of NGC 891, it would likely be detected in our narrowband H\alpha CCD images acquired at Mont Megantic (sensitivity = 1.2 \times 10^-16\ erg \ cm^2 \ s^-1\ arcsec^-2). Our non-detection of an ionized halo is consistent with the suggestion that only galaxies with FIR luminosities greater than 3 \times \ 10^43 \ erg\ s^-1 have both a thick radio continuum disk and a thick ionized layer. Since there is no strong correlation between star formation regions and the morphology of the radio halo, this extended radio continuum may be a product of the interaction between NGC 3432 and UGC 5983 rather than the result of a connection between the disk and halo of NGC 3432.