A SEARCH FOR LITHIUM IN CATACLYSMIC BINARIES

The discovery of Li in the late type secondary of the black hole binary V404 Cyg has motivated considerable interest in the presence of this light element in stars orbiting compact objects in general. We report here on a search for Li in cataclysmic binaries (CVs), where a low mass star transfers mass onto a white dwarf. For this purpose, we have taken spectra in the Li I lambda 6708 region of eight CVs, and we have also compiled existing data. In eight CVs with visible photospheric absorption lines from the secondary, we find no evidence for Li. Our upper limits to the Li abundance in these CVs are lower than the abundance found in the secondary of V404 Cyg by factors in the range 2 to 300. The implications for understanding the Li observed in several X-ray transients, are discussed. One of the CVs that we have observed, GK Per, is known to have undergone a recent nova outburst (Nova Persei 1901), and hence our observations do not support models predicting large Li production in classical novae.