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Context. The black hole candidate GX 339-4 exhibited an X-ray outburst inJanuary 2010, which is still continuing. We here discuss the timing and thespectral properties of the outburst using RXTE data. Aims. Our goal is to studythe timing and spectral properties of GX 339-4 using its recent outburst dataand extract information about the nature of the accretion flow. Methods. We useRXTE archival data of the recent GX 339-4 outburst and analyze them with theNASA HEAsoft package, version 6.8. We then compare the observed quasi-periodicoscillation (QPO) frequencies with those from existing shock oscillation modeland obtain the nature of evolution of the shock locations during the outburst.Results. We found that the QPO frequencies are monotonically increasing from0.102 Hz to 5.69 Hz within a period of ~ 26 days. We explain this evolutionwith the propagating oscillatory shock (POS) solution and find the variation ofthe initial and final shock locations and strengths. The model fits also givethe velocity of the propagating shock wave, which is responsible for thegeneration of QPOs and their evolutions, at ~ 10 m/s. We observe from thespectra that up to 2010 April 10, the object was in a hard state. After that,it went to the hard-intermediate state. On April 18, it had a state transitionand went to the soft-intermediate state. On May 15, another state transitionwas observed and the source moved to the soft state. Conclusions. As in thepreviously fitted outburst sources, this source also showed the tendency of arapidly increasing QPO frequency ($\nu_{QPO}$) in a viscous time scale, whichcan be modeled quite accurately. In this case, the shock seems to havedisappeared at about ~ 172 Schwarzschild radii, unlike in the 2005 outburst ofGRO J1655-40, where the shock disappeared behind the horizon.

Properties of the propagating shock wave in the accretion flow around GX 339-4 in the 2010 outburst