Bibcode
Hensley, Kerry G.; Kwitter, Karen B.; Corradi, Romano; Galera-Rosillo, R.; Balick, Bruce; Henry, Richard B. C.
Bibliographical reference
American Astronomical Society, AAS Meeting #224, #121.08
Advertised on:
6
2014
Citations
0
Refereed citations
0
Description
As part of a continuing project using planetary nebulae (PNe) to study
the chemical evolution and formation history of M31 (see accompanying
poster by Balick et al.), we obtained spectra of eight PNe in the fall
of 2013 with the OSIRIS spectrograph on the GTC. All of these PNe are
located outside M31’s inner disk and bulge. Spectral coverage
extended from 3700-7800Å with a resolution of ~6 Å.
Especially important in abundance determinations is the detection of the
weak, temperature-sensitive auroral line of [O III], at 4363Å,
which is often contaminated by Hg I 4358Å from streetlights; the
remoteness of the GTC eliminated this difficulty. We reduced and
measured the spectra using IRAF, and derived nebular diagnostics and
abundances with ELSA, our in-house five-level-atom program. Here we
report the chemical abundances determined from these spectra. The bottom
line is that the oxygen abundances in these PNe are all within a factor
of 2-3 of the solar value, (as are all the other M31 PNe our team has
previously measured) despite the significant range of galactocentric
distance. Future work will use these abundances to constrain models of
the central star to estimate progenitor masses and ages. In particular
we will use the results to investigate the hypothesis that these PNe
might represent a population related to the encounter between M31 and
M33 ~3 Gy ago. We gratefully acknowledge support from Williams College.