Using the data from the Rossi X-Ray Timing Explorer satellite , we investigate the spectral evolution along a ‘ ‘ Z ’ ’ track and a ‘ ‘ \nu ’ ’ track on the hardness-intensity diagrams of the first transient Z source XTE J1701 - 462 .
The spectral analyses suggest that the inner disk radius depends on the mass accretion rate , in agreement with the model prediction , R _ { in } \propto { \dot { M } _ { disk } } ^ { 2 / 7 } , for a radiation pressure dominated accretion disk interacting with the magnetosphere of a neutron star ( NS ) .
The changes in the disk mass accretion rate \dot { M } _ { disk } are responsible for the evolution of the ‘ ‘ Z ’ ’ or ‘ ‘ \nu ’ ’ track .
The radiation pressure thickens the disk considerably , and also produces significant outflows .
The NS surface magnetic field strength , derived from the interaction between the magnetosphere and the radiation pressure dominated accretion disk , is \sim ( 1–3 ) \times 10 ^ { 9 } G , which is possibly between normal atoll and Z sources .
A significant hard tail is detected in the horizontal branches and we discuss several possible origins of the hard tail .