Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Globular Cluster Photometry with the Hubble Space Telescope VII. Color
  Gradients and Blue Stragglers in the Central Region of M30 (NGC 7099) from
  WFPC2 Observations   We present F555W (V), F439W (B), and F336W (U) photometry of 9507 stars in
the central 2' of the dense, post core collapse cluster M30 (NGC 7099) derived
from HST WFPC2 images. These data are used to study the mix of stellar
populations in the central region of the cluster. Forty eight blue straggler
stars are identified and are found to be strongly concentrated towards the
center. The specific frequency of blue stragglers, F_BSS\equiv
N(BSS)/N(V<V_HB+2), is 0.25\pm 0.05 in the inner region of M30 (r<20''),
significantly higher than the frequency found in other clusters. The shape of
M30's BSS luminosity function resembles the prediction of the collisional
formation model and is inconsistent with the binary merger model, of Bailyn and
Pinsonneault. An unusually blue star (B=18.6,B-V=-0.97), possibly a cataclysmic
variable based on its color, is found about 1.2'' from the center. Bright RG
stars appear to be depleted by a factor of 2--3 in the inner r<10'' relative to
fainter giants, subgiants, and MSTO stars (95% significance). We confirm that
there is a radial gradient in the color of the cluster light, going from
B-V=0.82 at r=1' to B-V=0.45 in the central 10''. The central depletion of the
bright RG is responsible for about half of the observed color gradient; the
rest of the gradient is caused by the relative underabundance of faint red MS
stars near the center (presumably a result of mass segregation). The luminosity
function of M30's evolved stars does not match the luminosity function shape
derived from standard stellar evolutionary models: the ratio of the number of
bright giants to the number of turnoff stars in the cluster is 30% higher than
predicted by the model (3.8\sigma effect), roughly independent of RG brightness
over the range M_V=-2 to +2. (abridged)

15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom