Based on observations made at the Special Astrophysical Observatory, Nizhnij Arkhyz, Russia, and at the German-Spanish Astronomical Center, Calar Alto, Spain.

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However, it should be noted that, while the tidal force decreases with distance, the spiral shocks can amplify within the disk as it travels inwards (Spruit 1987).

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... curves

Due to the wavelength response of the detectors used during the first observations, the signal-to-noise ratio (S/N) of H $\beta$ is significantly higher than of the other lines. Therefore, this discussion is mainly based on the H $\beta$ line. However, these results are completely consistent with the behaviour of H $\gamma$ and H $\delta$ .

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... line''

In calculations of Bisikalo et al. (1998a, 1998b) and Makita et al. (2000), the gas stream from L₁ did not cause the shock perturbation of the disk boundary. It meant the absence of the "hot spot''. At the same time, the gas of the "circumbinary envelope'' interacts with the stream and causes the formation the extended shock wave, located on the stream edge ("hot line'').

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... system.

Bisikalo et al. (1998a, 1998b) also claimed that we see only the one-armed spiral shock. In the place where the second arm should be (region B) the stream from L₁ dominates and presumably prevents the formation of second arm of tidally induced spiral shock. The last claim is disputed by Makita et al. (2000) and this problem remains unclosed. From the observation side these two versions practically are indiscernible.

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... blob

It is fair to say that Bath (1973) was the first who suggested the presence of the blobs in the accretion disks, though the Bath's blobs are quite different than the one described here.

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