| Apresentação/Painel: | |
| Autor: | Denise R. Gonçalves1 |
| Laura Magrini2 | |
| Instituição: | 1OV/UFRJ - Rio de Janeiro |
| 2INAF - Osservatorio Astrofisico di Arcetri | |
| Formato: | Painel |
| Título: | Gemini GMOS: the chemical evolution of the Local Group dwarf galaxies |
| Resumo: |
This contribution highlights the GMOS-Gemini spectroscopy of NGC147 and
IC10, two dwarf galaxies of the Local Group (LG). The former is a dwarf
spheroidal galaxy (dSph) and the latter is a dwarf irregular galaxy (dIrr),
thus being opposite in terms of their present star formation rate, gas and
dust content, as well as dominant stellar population. Our aim is to
reconstruct the SFH of both galaxies and to derive their age metallicity
(AM) relationships using young (HII regions) and intermediate to old-age
stars (planetary nebulae, PNe). The direct availability of the electron
temperature in our emission-line (HII regions plus PNe) spectra allows an
accurate determination of the NGC147 and IC10 metallicity maps at two
different epochs. For NGC147, which does not possess HII regions, we find
that the old stellar population metallicity is similar to the PN metallicity,
so suggesting a negligible chemical enrichment during a substantial amount
of time. In IC10 we find an inhomogeneous distribution of metals for HII
region and PN populations with a dispersion of about 0.2 dex. In addition,
the AM relationship shows a little global enrichment, which is interpreted
as due to the loss of metals by supernovae winds and to differential gas
outflows.
To point out the relevance of this type of study for the formation of dwarf galaxies and the evolution of the LG, we also discuss our results in terms of the metallicity-luminosity relationship of dIrrs and dSphs. We study this relation to test the proposition that dSphs are formed through the removal of the gas in dIrrs, either through ram pressure stripping, supernova driven winds or star formation. |
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