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We have performed radio polarization observation experiments of the stars V772 Her and β Per with the Urumqi 25 m radio telescope at the 6 cm waveband, and obtained light curves of the stars after data processing and calibration. A radio flare from the star V772 Her was detected on 2011 April 13. The degree of linear polarization of this flare is about 30%, and the polarization angle is about 4°. We have detected also the slowly-varying component of the radio radiation from β Per, as well as a short flare superposed on it, which has a very weak linear polarization.

The predictions of the modified gravitational model MOND and the model of dark matter for the earth's gravitational system are examined. We focus on the commonly used MOND models. For the simplest of these models, we present a general expression for the gravitational potential in the case of spherical symmetry, and calculate the predicted angular velocity of a satellite moving in the field. It is found that the angular velocity is different in the different MOND models, that the differences between the predictions of these models and the Newtonian theory are very small, but that the difference in the simplest case ( n = 1) is larger. In the case of the moon, actual measurements with existing techniques can be possibly made for this difference in angular velocity. We have also estimated the influence on the angular velocity of the moon due to the model of dark matter, and found it to be far smaller than the effect of the MOND theory. Therefore, the measurement of this difference in angular velocity may provide a criterion for discriminating the MOND theory and the model of dark matter.

On the basis of the new Galactic rotation curve and constants R 0 and V 0 , and using HII regions, giant molecular clouds and other tracer objects, we have revised the pattern of the Sagittarius-Carina arm of our Galaxy. We have derived its pitch angle to be about 12°, and explored the dependence of the pitch angle on the Galactic constants. The result indicates that with decreasing Galactic constants, the pitch angle increases, and so does the number of spiral arms, according to the symmetric logarithmic arms model. In addition, the halo mass of our Galaxy will decrease with the flattening and downward turn of the rotation curve.

We have searched 11 304 quasars from the NVSS catalog for radio emission and obtained 2 626 positive detections, of which 301 are new radio detections. We made statistical studies of the radio spectral index, radio luminosity and the fraction of radio-loud quasars versus absolute B magnitude and redshift. We found that the fraction rises between MB = −22 and −30 and that it increases at z = 0.0 until z = 0.8, then goes down at z = 1.5. The degree of polarization shows no dependence on redshift.

The relative spectra of the leading and the trailing components of 23 conal-double pulsars are measured and investigated. They are in a simple power-law generally and the relative spectral indices are concentrated in a narrow range around zero, which suggests that the leading and trailing components come from the same emission ring. The scatter of the relative spectral indices is probably caused by unsymmetrical location of the components with respect to the center.

We made a periodicity analysis for 3197 quasars in the Veron-Cetty and Veron catalogue with accurate redshifts. The result is that there exist high frequency periodicities in the quasar redshift values in several directions, at a high level of confidence. According to our analysis, these periodicities cannot be all due to selection effects, and the distribution of quasars in space probably contains fluctuations on scales around 50 Mpc.

We discussed the physical background of the unified scaling law in spiral galaxies, and qualitatively obtained the power index of the empirical relation among the luminosity L, radius R and the rotation velocity V. We also discussed the possible causes for the data dispersion on the plane in three-dimensional space of these parameters.