IMAGING AND SPECTROSCOPY OF 10 SOUTHERN GALAXIES SELECTED FROM A CATALOG OF PECULIAR GALAXIES

Citation
Cj. Donzelli et Dl. Ferreiro, IMAGING AND SPECTROSCOPY OF 10 SOUTHERN GALAXIES SELECTED FROM A CATALOG OF PECULIAR GALAXIES, Astronomy & Astrophysics. Supplement series, 127(3), 1998, pp. 527-542
Citations number
29
Categorie Soggetti
Astronomy & Astrophysics
ISSN journal
03650138
Volume
127
Issue
3
Year of publication
1998
Pages
527 - 542
Database
ISI
SICI code
0365-0138(1998)127:3<527:IASO1S>2.0.ZU;2-T
Abstract
We present BVRI broad band photometry and long slit spectroscopy for a sample of ten southern galaxies selected from the Aguero Catalogue of Peculiar Galaxies. The analysis of tile images shows that only four g alaxies 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 pec uliar galaxies we did not find evidence of mergers in our analysis of images and rotation curves. Almost all galaxies in our sample show sta r 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. Inn our photometric analysis we did no t find characteristics that could distinguish between normal and pecul iar galaxies. We obtained the ''pure-emission'' line spectra for six g alaxies of the sample by subtracting appropriate templates. These temp lates 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 tie spiral galaxy of the interact ing 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 :Se yfert 2 galaxy, AM 2054-433 N. For this SO galaxy the line flux ratios measured from tile 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 h igher star-formation rate than normal galaxies, as measured by H alpha + [NII] line emission. The observed EW(H alpha + [NII]) values for th ese peculiar galaxies are around 60 Angstrom; compared to 22 Angstrom for normal galaxies. Whole-aperture spectra for these peculiar galaxie s show very similar EW(H alpha + [NII]) values to those observed in th eir nuclear region suggesting thats global starburst has occurred. Alt hough our sample is;small the results presented suggest that peculiar morphology and global starburst events are closely related.