Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Presence of Two Distinct Red Giant Branches in the Globular Cluster
  NGC 1851   There is a growing body of evidence for the presence of multiple stellar
populations in some globular clusters, including NGC 1851. For most of these
peculiar globular clusters, however, the evidence for the multiple red
giant-branches (RGBs) having different heavy elemental abundances as observed
in Omega Centauri is hitherto lacking, although spreads in some lighter
elements are reported. It is therefore not clear whether they also share the
suggested dwarf galaxy origin of Omega Cen or not. Here we show from the CTIO
4m UVI photometry of the globular cluster NGC 1851 that its RGB is clearly
split into two in the U - I color. The two distinct RGB populations are also
clearly separated in the abundance of heavy elements as traced by Calcium,
suggesting that the type II supernovae enrichment is also responsible, in
addition to the pollutions of lighter elements by intermediate mass asymptotic
giant branch stars or fast-rotating massive stars. The RGB split, however, is
not shown in the V - I color, as indicated by previous observations. Our
stellar population models show that this and the presence of bimodal
horizontal-branch distribution in NGC 1851 can be naturally reproduced if the
metal-rich second generation stars are also enhanced in helium.

19
The categories of this paper are: eess
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
24
The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
16
The categories of this paper are: stat