New measurement of metal abundance in the elliptical galaxy NGC 4636 with ASCA

High-quality X-ray spectra of NGC 4636 are obtained with ASCA. Theoretical models are found unable to reproduce the data in the Fe-L line region. Spectral data above 1.4 keV indicate that the Mg to Si abundance ratio is similar to 1 solar. Assuming that the abundance ratios among a elements are the same as the soar ratios, a spectral fit with increased systematic error in the 0.4-1.6 keV range gives abundances of ct elements and Fe to be both similar to 1 solar by taking 1 solar of Fe to be 3.24 x 10(-5) by number. These new abundance results solve the discrepancy between stellar and hot-gas metallicity, but still a low supernova rate is implied. We also detect strong abundance gradients for both a elements and iron in a similar fashion. The abundance is similar to 1 solar within 4' and decreases outward down to 0.2-0.3 solar at 10' from the galaxy center. Dilution due to an extended hot gas is suggested.