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Parkash et al. have examined a sample of 91 galaxies, selected from
the HI Parkes All-Sky Survey (HIPASS), that infrared observations
suggest have little or no star formation. Inspection of optical
images of 62 of the galaxies revealed that at least 32 galaxies in the
sample have low levels of star formation, primarily in arms/rings.
From a spectroscopic analysis of HI selected galaxies with little star
formation, they conclude that 75% of this population have
low-ionisation nuclear emission-line regions (LINERs) or extended
low-ionisation emission-line regions (LIERs). The images above are
from the Carnegie Irvine Galaxy Survey (CGS). The bottom left of each
postage stamp includes notes on the optical features of the galaxy:
bars (B), rings (R), star formation in the outer region (SF), edge-on
(EO) and dust lanes (DL). Full results are published in
the paper published in
Monthly Notices of the Royal Astronomical Society.
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