To aid future observations, we present the results of N‐body simulations of tidal tails near the open cluster NGC 188. The simulated tidal tails stretch in both directions along the Galactic orbit of the cluster, extending to distances of at least 1 kpc. The cross‐section of a tidal tail does not exceed 40–50 pc. On the sky, the number of tidal stars in the densest parts of a tail can reach a few percent of all visible stars only. The average dispersion of stellar velocities in the tidal tail is 1–3 km s−1. In velocity space, the tidal tails have a shape of a lengthy ‘cold’ star flux immersed in the ‘hot’ Galactic disc background. We provide the predicted position of the tidal tails and the expected distribution of radial velocities along the projection. The expected distribution of tidal star radial velocities has a large range (from −46 to +49 km s−1), thus underscoring the importance of predictions in future searches of tidal stars in open clusters. A preliminary search for tidal stars in the Two‐Micron All‐Sky Survey catalogue was not successful, indicating the need for a new CCD imaging to narrow down the number of possible former members of NGC 188 within the specified range of photometric and kinematic parameters.

As compared with the Mount Wilson Magnetic Classification (MWMC), effective distance (d E ) is a useful parameter because it gives a quantitative measure of magnetic configuration in active regions. We have analyzed magnetograms of 24 active regions of different types with MWMC. We have studied the evolution of magnetic fields of five active regions using d E , total flux (F t ) and tilt angle (Tilt) quantitatively. Furthermore, 43 flare-associated and 25 CME-associated active regions have been studied to investigate and quantify the statistical correlation between flares/CMEs and the three parameters. The main results are as follows: (1) There is a basic agreement between d E and MWMC.(2) The evolution of magnetic fields can be described in three aspects quantitatively and accurately by the three parameters, in particular by d E on the analysis of δ-type active regions. (3) The high correlation between d E and flares/CMEs means that d E could be a promising measure to predict the flare-CME activity of active regions.

Aims. We study the properties of magnetic field of flare-coronal-mass-ejection (flare-CME) productive active regions and their statistic correlations with CME speed. Methods. We used a sample of 86 flare-CMEs in 55 solar active regions. Four measures, including the tilt angle (Tilt), total flux (Ft), length of the strong-field and strong-gradient main neutral line (Lsg) and effective distance (d E ), are used to quantify the properties of the magnetic field of flare-CME productive active regions. (4) The occurrence of 11 slow CMEs and 1 fast CME in β type regions with Lsg far below the threshold reminds us of some exceptions to be considered when Lsg with the threshold is used to predict the CME productivity of active regions.

To predict the key parameters of the solar cycle, a new method is proposed based on the empirical law describing the correlation between the maximum height of the preceding solar cycle and the entropy of the forthcoming one. The entropy of the forthcoming cycle may be estimated using this empirical law, if the maximum height of the current cycle is known. The cycle entropy is shown to correlate well with the cycle's maximum height and, as a consequence, the height of the forthcoming maximum can be estimated. In turn, the correlation found between the height of the maximum and the duration of the ascending branch (the Waldmeier rule) allows the epoch of the maximum, Tmax, to be estimated, if the date of the minimum is known. Moreover, using the law discovered, one can find out the analogous cycles which are similar to the cycle being forecasted, and hence, obtain the synoptic forecast of all main features of the forthcoming cycle. The estimates have shown the accuracy level of this technique to be 86%. The new regularities discovered are also interesting because they are fundamental in the theory of solar cycles and may provide new empirical data. The main parameters of the future solar cycle 24 are as follows: the height of the maximum is Wmax = 95±20, the duration of the ascending branch is Ta = 4.5±0.5 yr, the total cycle duration according to the synoptic forecast is 11.3 yr.

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