Abstract.
We present radio and follow-up optical observations of a sample of
bulgeless late type spiral galaxies. We searched for signs of
nuclear activity and disk star formation in the sample galaxies.
Interaction induced star formation can often trigger bulge
formation. We found significant radio emission associated with star
formation in two sample galaxies, NGC3445 and NGC4027, both of which
are tidally interacting with nearby companions. For the others, the
star formation was either absent or limited to only localized
regions in the disk. Both galaxies also have oval bars that are
possibly pseudobulges that may later evolve into bulges. We did
follow up optical Hα imaging and nuclear spectroscopy of
NGC3445 and NGC4027 using the Himalayan Chandra Telescope (HCT). The
Hα emission is mainly associated with strong spiral arms that
have been triggered by the tidal interact1ions. The nuclear spectra
of both galaxies indicate ongoing nuclear star formation but do not
show signs of AGN activity. We thus conclude that star formation in
bulgeless galaxies is generally low but is enhanced when the
galaxies interact with nearby companions; this activity may
ultimately lead to the formation of bulges in these galaxies.
Key words:galaxies: active -- galaxies: bulges -- galaxies:
spiral -- galaxies: interactions -- radio continuum: galaxies