Chandra grating spectroscopy of the Seyfert galaxy Ton S180

We present preliminary results from spectral observations of Ton S180 using Chandra and ASCA. The data confirm the presence of the soft excess, but th e Chandra Low-Energy Transmission Grating spectrum reveals it to be broad a nd smooth rather than resolved into individual emission lines. This excess may represent either a primary or reprocessed continuum component or a blen d of broad lines from an ionized accretion disk. The occurrence of a simila r feature in five other narrow-line Seyfert 1 galaxies leads us to conclude that this soft X-ray component may be a characteristic of sources accretin g at a high rate. The X-ray spectrum shows no evidence for absorption lines , indicating that if gas exists in the line of sight then it is in a very h igh ionization state or has an extreme velocity distribution. The new ASCA data confirm that the narrow component of the Fe K alpha line peaks close t o a rest energy of 7 keV, indicating the presence of a significant amount o f highly ionized material in the nuclear environs.