Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the nature of the compact star in 4U 1728-34   The discovery of kilohertz quasi-periodic oscillations (kHz QPOs) in low-mass
X-ray binaries (LMXBs) with the Rossi X-ray Timing Explorer has stimulated
extensive studies of these sources. Recently, Osherovich & Titarchuk suggest a
new model for kHz QPOs and the related correlations between kHz QPOs and low
frequency features in LMXBs. Here we use their results to study the mass -
radius relation for the atoll source 4U 1728-34. We find that, if this model is
correct, 4U 1728-34 is possibly a strange star rather a neutron star.

11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat