Detection of an intense iron line at 6.4 keV in the X-ray spectrum ofNGC 4151.

The authors present the X-ray spectrum of NGC 4151 observed with the gas scintillation proportional counters (GSPC) on board Tenma. The energy resolution of the GSPC is twice that of the proportional counters used in the past observations, which enables one to obtain detailed properties of the iron emission line from NGC 4151. The GSPC detected a clear emission line at 6.4 keV from NGC 4151 in spite of the low X-ray intensity level of the source. The authors examine the intense iron emission line. To this end they evaluate the iron column density from the depth of the iron K-edge absorption and compare this to the hydrogen column density derived from the low energy cutoff. The authors then discuss the abundance of iron and the geometrical configuration of the matter responsible for the iron line in relation to the derived column densities.