NuSTAR observations of the neutron star low-mass X-ray binary GX 349+2 throughout its Z-track

Although the brightest class of neutron star low mass X-ray binaries, known as Z-sources, have been well studied, their behavior is not fully understood. In particular, what causes these sources to trace out the characteristic Z-shaped pattern on color-color or hardness-intensity diagrams is not well known. By studying the physical properties of the different spectral states of these sources, we may better understand such variability. With that goal in mind, we present a recent NuSTAR observation of the Z-source GX 349+2, which spans approximately 2 days, and covers all its spectral states. By creating a hardness-intensity diagram we were able to extract four spectra and trace the change in spectral parameters throughout the Z track. GX 349+2 shows a strong, broad Fe Kα line in all states. Through modeling of the reflection spectrum and Fe Kα line we find that in most states the inner disk radius is consistent with remaining unchanged, and being close to the neutron star. However, during the brightest flaring branch the inner disk radius from reflection is not well constrained.