A&A Supplement series, Vol. 127, February I 1998, 527-542
Received December 10, 1996; accepted June 16, 1997
C.J. Donzelli
and D.L. Ferreiro
Send offprint request: C.J. Donzelli
IATE, Observatorio Astronómico, Universidad
Nacional de Córdoba,
Laprida 854, 5000 Córdoba, Argentina
We present BVRI broad band photometry and long slit
spectroscopy for a sample of ten southern galaxies selected
from the Agüero Catalogue of Peculiar Galaxies.
The analysis of the images shows that only four galaxies of
the sample are truly peculiar galaxies and four are normal
spirals. The remaining two galaxies, a normal spiral and a
SO, form an interacting pair. Despite the rather complicated
structure of the peculiar galaxies we did not find evidence
of mergers in our analysis of images and rotation curves.
Almost all galaxies in our sample show star forming regions
with very blue colors, (B-V) ranging from 0.2 to 0.6. The SO
galaxy shows a very interesting structure in the V-I color
map suggesting that star formation events have occurred in
concentric annuli centered in the nucleus. In our
photometric analysis we did not find characteristics that
could distinguish between normal and peculiar galaxies.
We obtained the "pure-emission'' line spectra for six
galaxies of the sample by subtracting appropriate templates.
These templates correspond to ellipticals selected from our
library of spectra. This subtraction technique provides a
powerful tool to calculate line flux ratios uncontaminated
by the underlying stellar population.
Our spectroscopic analysis confirms that the spiral galaxy
of the interacting system AM 2054-433 has a LINER-type
nucleus. In the normal galaxy ESO 316-29 we find evidence
of a LINER nucleus and we report a new Seyfert 2 galaxy, AM
2054-433 N. For this SO galaxy the line flux ratios measured
from the pure-emission spectrum are indicative of a Seyfert
2 rather than a LINER nucleus as it was previously reported
by other authors.
Three of the four peculiar galaxies in our sample have much
higher star-formation rate than normal galaxies, as measured
by H
+ [NII] line emission. The observed
EW(H + [NII]) values for these peculiar galaxies are
around 60 Å, compared to 22 Å for normal galaxies.
Whole-aperture spectra for these peculiar galaxies show very
similar EW(H + [NII]) values to those observed in
their nuclear region suggesting that a global starburst has
occurred. Although our sample is small the results presented
suggest that peculiar morphology and global starburst events
are closely related.
keywords: galaxies: peculiar -- galaxies: photometry -- galaxies: starburst -- galaxies: interactions