We present HST/FOS ultraviolet and optical spectroscopy of the black hole X-ray transient GRO J0422+32 shortly before the system reached quiescence. We find that the accretion spectrum from 2500 to 9000 Å can be very well fitted by a self-absorbed synchrotron model, with superposed H I and Mg II emission lines. The explanations that we suggest for this spectrum are either that it is due to active coronal regions above a geometrically thin accretion disc, or that the disc is evaporated into an advective flow.
Publication Source (Journal or Book title)
Monthly Notices of the Royal Astronomical Society
Hynes, R., & Haswell, C. (1999). Hubble space telescope observations of the black hole X-ray transient GRO J0422+32 near quiescence. Monthly Notices of the Royal Astronomical Society, 303 (1), 101-106. https://doi.org/10.1046/j.1365-8711.1999.02227.x