Indirect imaging of the accretion stream in eclipsing polars - II. HU Aquarii

We apply our technique for indirect imaging of the accretion stream to the polar HU Aquarii, using eclipse profiles observed when the system was in a high accretion state. The accretion stream is relatively luminous, contribu ting as much as the accretion region on the white dwarf, or more, to the ov erall system brightness. We model the eclipse profiles using a model stream consisting of a ballistic trajectory from the L1 point followed by a magne tically channelled trajectory that follows a dipole field line out of the o rbital plane. We perform model fits using two geometries: a stream that acc retes on to both footpoints of the field line, and a stream that accretes o nly on to the footpoint of the field line above the orbital plane. The stre am images indicate that the distribution of emission along the stream is no t a simple function of the radial distance from the white dwarf. The stream is redirected by the magnetic field of the white dwarf at a distance 1.0-1 .3 x 10(10) cm from the white dwarf; this implies a mass transfer rate in t he range 8-76 x 10(16) g s(-1). The absorption dips in the light curve indi cate that the magnetically entrained part of the stream moves from 42 degre es to 48 degrees from the line of centres over the three nights of observat ion. This is in close agreement with the results of the one-footpoint model s, suggesting that this is the more appropriate geometry for these data. Th e stream images show that, in almost all sections of the stream, the flux p eaks in B and is successively fainter in U, V and R.