X-ray properties of the Abell 644 cluster of galaxies

We use new ASCA observations and archival ROSAT PSPC data to determine the X-ray spectral properties of the intracluster gas in Abell 644. From the overall spectrum, we determine the average gas temperature to be 8.64(-0.56)(+0.67) keV and an abundance of 0.32 +/- 0.04 Z.. The global ASCA and ROSAT spectra imply a cooling rate of 214(-91)(+100) M. yr(-1). The PSPC X-ray surface brightness profile and the ASCA data suggest a somewhat higher cooling rate. We determine the gravitational mass and gas mass as a function of radius. The total gravitating mass within 1.2 Mpc is 6.2 x 10(14) M., of which 20% is in the form of hot gas. There is a region of elevated temperature 1.'5-5' to the west of the cluster center. The south-southwest region of the cluster also shows excess emission in the ROSAT PSPC X-ray image, aligned with the major axis of the optical cD galaxy in the center of the cluster. We argue that the cluster is undergoing or has recently undergone a minor merger. The combination of a fairly strong cooling flow and evidence for a merger make this cluster an interesting case to test the disruption of cooling flow in mergers.