Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Stellar Populations in Ten Clump-Cluster Galaxies of the Ultra Deep
  Field   Color-color diagrams for the clump and interclump emission in 10
clump-cluster galaxies of the Ultra Deep Field are made from B,V,i, and z
images and compared with models to determine redshifts, star formation
histories, and galaxy masses. The clump colors suggest declining star formation
over the last ~0.3 Gy, while the interclump emission is older. The clump
luminous masses are typically 6x10^8 Msun and their diameters average 1.8 kpc.
Total galaxy luminous masses average 6.5x10^10 Msun. The distribution of axial
ratios is consistent with a thick disk geometry. The ages of the clumps are
longer than their internal dynamical times by a factor of ~8, so they are
stable clusters, but the clump densities are only ~10 times the limiting tidal
densities, so they could be deformed by tidal forces. This is consistent with
the observation that some clumps have tails. The clumps could form by
gravitational instabilities in accreting disk gas, or they could be captured as
gas-rich dwarf galaxies. Support for this second possibility comes from the
high abundance of nearly identical bare clumps in the UDF field. Several
clump-clusters have disk densities that are much larger than in local disks,
suggesting they do not survive but get converted into ellipticals by
collisions.

0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
18
The categories of this paper are: econ