  A paper by Qian & Wasserburg suggests the optical absorption lines of uranium
observed in the spectra of ultra-metal-poor stars (defined as [Fe/H] $<$-3)
arise from contamination from a supernova in a binary star system. Assuming the
binary survived the explosion, a collapsed compact object may be present and
implying potential accretion processes with accompanying X-ray emission. Upper
limits on X-ray emission from an accreting compact object are described here.
