Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Ellipticity of the Disks of Spiral Galaxies   The disks of spiral galaxies are generally elliptical rather than circular.
The distribution of ellipticities can be fit with a log-normal distribution.
For a sample of 12,764 galaxies from the Sloan Digital Sky Survey Data Release
1 (SDSS DR1), the distribution of apparent axis ratios in the i band is best
fit by a log-normal distribution of intrinsic ellipticities with ln epsilon =
-1.85 +/- 0.89. For a sample of nearly face-on spiral galaxies, analyzed by
Andersen and Bershady using both photometric and spectroscopic data, the best
fitting distribution of ellipticities has ln epsilon = -2.29 +/- 1.04. Given
the small size of the Andersen-Bershady sample, the two distribution are not
necessarily inconsistent. If the ellipticity of the potential were equal to
that of the light distribution of the SDSS DR1 galaxies, it would produce 1.0
magnitudes of scatter in the Tully-Fisher relation, greater than is observed.
The Andersen-Bershady results, however, are consistent with a scatter as small
as 0.25 magnitudes in the Tully-Fisher relation.

30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph