3. RESULTS

3.1. General results

This current H survey comprises of 65 nearby edge-on galaxies. 59 of these galaxies have been observed during the course of this survey, whereas we have added 6 additional target galaxies, from which we had H data at our disposal. Taking the 9 edge-on galaxies from our first sample (Rossa & Dettmar, 2000) into consideration, the survey covers 74 galaxies in total. From these 74 galaxies 63 actually are new observations, whereas 11 galaxies have already been investigated in the DIG context by other researchers. We have included them because we wanted some galaxies for an intercomparison between our sample and the samples studied by other investigators. Furthermore, we wanted to have a more homogeneous sample in the sense of FIR luminosity, and thus included also a very few starburst galaxies. Needless to say that many starbursts fulfilled our selection criteria, but we did not want to re-observe all targets, and were also primarily interested in the galaxies with lower SF activity. The description of the selection criteria for the H survey target galaxies are presented in detail in Paper I (Rossa & Dettmar, 2003). Far below (Table 5) we present the DIG morphology of the sample galaxies with information on the vertical extent (| z|), and the radial extent of the star formation activity (R_SF [kpc]).

As already mentioned our extended survey, which includes the 9 previously investigated galaxies presented in an earlier work (Rossa & Dettmar, 2000), consists of a grand total of 74 galaxies. 30 galaxies, that is almost 41% of our survey, show extraplanar DIG features (either a pervasive layer, and/or filaments, or plumes, etc.). Excluding the 9 galaxies (first sub-sample), there are still 24 galaxies out of 65 with eDIG detections left, that is ~ 37% of the survey. As we were primarily aiming to trace the fainter end of the SF activity, we were selecting galaxies with a broader range of L_FIR, compared to the galaxies, which were studied earlier by Lehnert & Heckman (1995), which were selected only on the basis of being infrared warm galaxies (S₆₀ / S₁₀₀ 0.4). Therefore, it is not surprising that we did detect a good fraction of galaxies with no extraplanar emission.