title: On the Nature of the Compact Star in 4U 1728-34.
abstract: 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 suggested 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 than a neutron star.
authors.initials: XD
authors.lastname: Li
authors.initials: S
authors.lastname: Ray
authors.initials: J
authors.lastname: Dey
authors.initials: M
authors.lastname: Dey
authors.initials: I
authors.lastname: Bombaci