We present narrowband H \alpha imaging data of a small survey of nearby edge–on spiral galaxies , aiming at the detection of ‘ extraplanar ’ diffuse ionized gas ( DIG ) .
A few of our studied edge–on spirals show signs of disk–halo interaction ( DHI ) , where extended line emission far above the galactic plane of these galaxies is detected .
In some cases an extraplanar diffuse ionized gas ( eDIG ) layer is discovered , e.g. , NGC4634 , NGC 3044 , while other galaxies show only filamentary features reaching into the halo ( e.g. , IC 2531 ) and some galaxies show no sign of eDIG at all .
The extraplanar distances of the DIG layer in our narrowband H \alpha images reach values of z \leq 2 kpc above the galactic plane .
The derived star formation rates ( SFRs ) from the H \alpha flux of the studied galaxies range from 0.05 - 0.7 { M _ { \sun } yr ^ { -1 } } , neglecting a correction for internal absorption .
The variation of the SFR values among our sample galaxies reflects the diversity of star formation within this sample .
A diagnostic diagram is introduced , which allows to predict the existence of gas halos in ‘ quiescent ’ galaxies based on the ratio { S _ { 60 } / S _ { 100 } } versus L _ { FIR } / D ^ { 2 } _ { 25 } in this diagram .
We compare the positions of the non–starburst galaxies with starburst galaxies , since these galaxies populate distinct positions in these diagrams .