Spectroscopy of PNe in Sextans A, Sextans B, NGC 3109 and Fornax
A.Y. Kniazev1, E.K. Grebel,
A.G. Pramskij, S.A. Pustilnik
1MPIA, Heidelberg, Germany
Planetary nebulae (PNe) and HII regions provide a probe of the chemical
enrichment and star formation history of a galaxy from intermediate
ages
to the present day. Furthermore, observations of HII regions and PNe
permit us to measure abundances at different locations, testing the
homogeneity with which heavy elements are/were distributed within a
galaxy.
We present the first results of NTT spectroscopy of HII regions and/or
PNe
in four nearby dwarf galaxies: Sextans A, Sextans B, NGC 3109, and
Fornax.
The first three form a small group of galaxies just beyond the Local
Group and are gas-rich dwarf irregular galaxies, whereas Fornax is a
gas-deficient Local Group dwarf spheroidal that stopped its star
formation activity a few hundred million years ago. For most PNe
(6 from 7 observed) and some of the HII regions in these galaxies we
have obtained element abundances via the classic Te-method
based
on the detection of the [OIII] λ4363 Å line.