Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spectroscopic Gradients in Elliptical Galaxies   Preliminary results based on a large compilation of line-strength profiles
are presented and discussed. Elliptical galaxies (Es) with strong central
Mg$_2$ show steeper line-strength gradients. These galaxies are more massive
and have higher velocity dispersions, note nevertheless, that the Mg$_2$
gradient correlates better with central Mg$_2$ than with any other global or
structural parameter. This correlation, and the fact that Mg$_2$ measures
$Z/Z_\odot$ together with the [Mg/Fe] abundances among Es, are of extreme
importance for the use of the central Mg$_2-\sigma$ relation as a reflection of
a mass-metallicity relation. Spectroscopic gradients arise mainly from a radial
decrease in mean stellar metallicity. However, the Mg$_2$ and $<{\rm Fe}>$
gradients do not correlate within measuring errors, indicating that something
else, besides metallicity, is also varying within a galaxy. H$\beta$ gradients
indicate that the centers of Es tend to look spectroscopically ``younger'' than
their stellar populations further out.

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The categories of this paper are: chem-ph
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The categories of this paper are: funct-an
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The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
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The categories of this paper are: patt-sol
1
The categories of this paper are: cs
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-alg
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-th
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The categories of this paper are: econ
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The categories of this paper are: mtrl-th
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The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: bayes-an