2000MNRAS.314..747S

We have obtained intermediate resolution optical spectra of the black-hole candidate Nova Sco 1994 in 1996 June, when the source was in an X-ray/optical active state (R∼15.05). We measure the radial velocity curve of the secondary star and obtain a semi-amplitude of 279±10km.s^–1; a value which is 30per cent larger than the value obtained when the source is in quiescence. Our large value for K₂ is consistent with 60-7+9per cent of the secondary star's surface being heated, compared with 35per cent, which is what one would expect if only the inner face of the secondary star were irradiated. Effects such as irradiation-induced flows on the secondary star may be important in explaining the observed large value for K₂.