Poster abstract details
PNe spectroscopy in the dwarf spheroidal NGC185: how to fake a Seyfert galaxy
Abstract
Elemental abundance ratios and their variation due to star formation are among the most important constraints of chemical evolution models. Due to the intrinsic faintness of dwarf galaxies, observational constraints to their evolution, such as the chemical abundances of stellar populations of different ages, can be obtained only for nearby galaxies. In this contribution we discuss properties based on the Gemini Multi-Object spectroscopy of the PNe in the dwarf spheroidal galaxy NGC185, one of the three dwarf companions of M31. These properties will be interpreted in terms of the chemical evolution of NGC185 itself, and, combined with the chemistry of other M31 dwarf satellites, in terms of the chemical evolution of the Andromeda group as a whole.
A very interesting and peculiar characteristic of NGC185 is the fact it is a dwarf spheroidal galaxy whose Seyfert-like line ratios may be produced by stellar processes. It is so because its AGN status was never confirmed since its nucleus was not detected at 6cm and 20cm radio continuum VLA surveys. So, although the weak emission lines in this galaxy formally place it in the category of Seyfert, it is probable that NGC185 does not contain a genuine active nucleus. It was previously suggested that the line emission of its central region come from its Post-AGB (PNe) population. For the first time this will be tested, together with other possible ionisation mechanisms with stellar origin. Stellar population synthesis and chemical evolution models based on the data we recently obtained will be used to support our conclusions.
A very interesting and peculiar characteristic of NGC185 is the fact it is a dwarf spheroidal galaxy whose Seyfert-like line ratios may be produced by stellar processes. It is so because its AGN status was never confirmed since its nucleus was not detected at 6cm and 20cm radio continuum VLA surveys. So, although the weak emission lines in this galaxy formally place it in the category of Seyfert, it is probable that NGC185 does not contain a genuine active nucleus. It was previously suggested that the line emission of its central region come from its Post-AGB (PNe) population. For the first time this will be tested, together with other possible ionisation mechanisms with stellar origin. Stellar population synthesis and chemical evolution models based on the data we recently obtained will be used to support our conclusions.