An Observation of the Intermediate Polar XY Arietis with Chandra

Chandra serendipitously observed the eclipsing (80° < i < 84°) intermediate polar XY Arietis (=H0253+193) in two separate but continuous observations 5 weeks apart. XY Ari was in a quiescent state during both observations. We pursue the study of phase-resolved spectra for this system by focusing on the Fe K lines. From the combined and separate data sets, we readily detect emission lines of iron near 6.4, 6.7, and 6.9 keV at better than 99% significance, in contrast to previous results. We confirm the orbit-phased sinusoidal absorption column behavior first observed with Ginga, as well as a sinusoid-like behavior as a function of spin phase. The presence of the 6.4, 6.7, and 6.9 keV lines requires different ionization states with ξ < 2 (6.4 keV) and ξ ∼ 3.5–4 (6.7 and 6.9 keV) that must vary with phase. We also detect emission lines at 3.25, 4.8, and 5.4 keV that are not instrumental in origin. The 4.8 keV line may be identified as Ca XIX (4.832 keV) and the 3.25 keV line may be Ar I K, but the 5.4 keV line has no obvious identification.