Um estudo espectrofotométrico de nebulosas planetárias e regiões HII na galáxia M83

Abstract

Planetary nebulae (PNe) and HII regions represent important tools with regard to determining chemical abundances and exploring radial abundance gradients in spiral galaxies. Both objects configure stellar populations with different ages, so the determination of their abundances allows to study the chemical composition of galaxies at different times of their evolution. In this work we aimed to determine the chemical abundances of the populations of PNe and HII regions in the barred spiral galaxy M83. Our data is made up of objects that are candidates for PNe and HII regions in M83 observed with the Gemini South telescope, which have not yet calculated chemical abundances. We obtained, for the first time, abundances by the direct method for two PNe of the galaxy M83. For ten HII regions in our sample, different statistical methods and calibrations were adopted to derive their abundances; and for only one of these HII regions, abundance was also obtained by the direct method. With the abundance of the two PNe it was possible, with the help of data from models of stellar evolution, to estimate the masses of their progenitor stars. The abundances calculated for the HII regions allowed us to explore the radial gradients of oxygen abundance. Our results show that the radial gradients differ according to the method adopted, both in height and inclination. The abundances of the two PNe, compared to the abundances of the HII regions by different methods, are lower. This result strengthens the hypothesis that a possible chemical enrichment happened in the barred spiral galaxy M83.