Karen B. Kwitter, Emma M. M. Lehman, Bruce Balick, R. B. C. Henry
We present spectroscopic observations and chemical abundances of 16 planetary
nebulae (PNe) in the outer disk of M31. The [O III] 4363 line is detected in
all objects, allowing a direct measurement of the nebular temperature essential
for accurate abundance determinations. Our results show that the abundances in
these M31 PNe display the same correlations and general behaviors as Type II
PNe in the Milky Way Galaxy. We also calculate photoionization models to derive
estimates of central star properties. From these we infer that our sample PNe,
all near the peak of the Planetary Nebula Luminosity Function, originated from
stars near 2 M_sun. Finally, under the assumption that these PNe are located in
M31's disk, we plot the oxygen abundance gradient, which appears shallower than
the gradient in the Milky Way.
View original:
http://arxiv.org/abs/1202.4933
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