Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Morphology and Evolution of LMC Planetary Nebulae   The LMC is ideal for studying the co-evolution of planetary nebulae (PNe) and
their central stars, in that the debilitating uncertainties of the Galactic PN
distance scale and selection biases from attenuation by interstellar dust do
not apply. We present images and analyze slit-less spectra which were obtained
in a survey of Large Magellanic Cloud PNe. These data on 29 targets were
obtained with HST using the Space Telescope Imaging Spectrograph. The data
permit us to determine the nebular dimensions and morphology in the
monochromatic light of several emission lines, including those that have
traditionally been used for morphological studies in the Galaxy: H-alpha, [N
II] 6583 and [O III] 5007, plus others of varying ionization, including [O I],
He I, and [S II]. Together with the 31 resolved LMC PNe for which monochromatic
images exist in the HST archive, these data show that the incidence of
non-symmetric nebulae, including bipolar nebulae (which is an indicator of
Population I ancestry in the Galaxy), is significantly higher than that
reported for the Galaxy. The onset of asymmetric features appears even in very
young nebulae (with dynamical ages of ~1400 yr), suggesting that at least the
gross features of the nebular morphology may be more closely tied to PN
formation, and that subsequent shaping of the expanding envelope by the
radiation field and wind from the central star may play the lesser role of
amplifying these gross features. There is some evidence of evolution between
two morphological types, in the sense that bipolar core (BC) nebulae may evolve
to pure bipolars late in the PN lifetime.

36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
18
The categories of this paper are: econ
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat