Spectroscopic observations of a sample of dwarf spirals galaxies. I.Oxygen abundances

TL;DR

This study reports new oxygen abundance measurements for four dwarf spiral galaxies using spectroscopic methods, revealing mostly sub-solar metallicities and similar chemical properties across different late-type galaxy types.

Contribution

First spectroscopic abundance analysis of four dwarf spiral galaxies, applying semi-empirical methods due to limited auroral line detection.

Findings

Three galaxies have sub-solar metallicities across regions.

One galaxy shows slightly over-solar abundances in some regions.

Metallicity range and N/O ratios are similar across different late-type galaxy classes.

Abstract

The oxygen abundances for four dwarf spiral galaxies have been determined using long-slit spectroscopy. The abundances of these galaxies have not previously reported in the literature. Several HII regions were detected in each galaxy. The electronic temperature method could be used only in one region because of the lack of the auroral lines of oxygen or sulfur. Therefore, four different semi empirical methods were used in the abundance determinations and a weighted-average abundance is obtained. The abundances of three of the galaxies are sub solar for all the regions, one of them having a very low metallicity. Only three HII regions in the fourth galaxy show slightly over solar abundances. Three of the HII regions might have a PN embedded. A comparison with the oxygen abundances among different types of late-type galaxies (BCG, LSBG, dI, Sm) is made. The conclusion is that all of them show the same range in metallicity. Also, the log(N/O) is similar, showing a secondary behaviour for abundances larger than 8.2 dex in spite of the morphological type of the mother galaxy.