Hydrogen-Poor Disks in Compact X-Ray Binaries

We show that accretion disks in several compact X-ray binaries with hydrogen– depleted donors are likely subject to a thermal ionization instability, unless they are strongly irradiated. These disks are particularly interesting in that their MHDturbulent properties in the neutral phase may be quite different from those of standard, hydrogen–rich disks. subject headings: X-ray: stars – accretion, accretion disks – MHD – turbulence