Abstract: We investigate atmospheric properties of 35 stable RRab stars that possess the full ranges of period, light amplitude, and metal abundance found in Galactic RR Lyrae stars. Our results are derived from several thousand echelle spectra obtained over several years with the du Pont telescope of Las Campanas Observatory. Radial velocities of metal lines and the Hα line were used to construct curves of radial velocity versus pulsation phase. From these we estimated radial velocity amplitudes for metal lines (formed near the photosphere) and Hα Doppler cores (formed at small optical depths). We also measured Hα emission fluxes when they appear during primary light rises. Spectra shifted to rest wavelengths, binned into small phase intervals, and co-added were used to perform model atmospheric and abundance analyses. The derived metallicities and those of some previous spectroscopic surveys were combined to produce a new calibration of the Layden abundance scale. We then divided our RRab sample into metal-rich (disk) and metal-poor (halo) groups at [Fe/H] = −1.0; the atmospheres of RRab families, so defined, differ with respect to (a) peak strength of Hα emission flux, (b) Hα radial velocity amplitude, (c) dynamical gravity, (d) stellar radius variation, (e) secondary acceleration during the photometric bump that precedes minimum light, and (f) duration of Hα line-doubling. We also detected Hα line-doubling during the

Abstract: We have presented here the results of a statistical study of two polar magnetic indices, computed from data from two near-pole geomagnetic observatories: Thule in the northern hemisphere and new, Concordia (Dome C) observatory near the southern geomagnetic pole in Antarctica. We found that:
The northern PMn and southern PMs polar magnetic indices show a good correlation with the solar wind/IMF parameters (the average correlation coefficient is ~ 0.87). Meanwhile, the southern PMs index shows a significantly better correlation than the northern PMn index, which demonstrates that the new Concordia observatory may play an important role in improving the Space Weather prediction.
The obtained results also show a high correlation between these two polar magnetic indices: the average correlation coefficient for this period was ~0.9 while for equinoctial months it increased up to 0.94-0.96.
Using the polar magnetic indices in two hemispheres may also significantly improve the prediction of other parameters, including the auroral electrojet AL index which shows substorm activity. Using the polar magnetic indices in two hemispheres allows us to predict the auroral electrojet AL index with a very high reliability (the correlation coefficient between predicted and actual AL indices is ~0.9, while for the equinoctial months the correlation coefficient was ~0.92).
The results of this study show an important role which is played by the magnetic disturbances in both polar ionospheres in developing the global magnetic activity, and the necessity to account for the magnetic disturbances in both ionospheres for improving the Space Weather prediction in the Geospace environment.

Abstract: We have found two pairs of earthquake doublets closely located antipodally on one diametral axis between Tonga-Algeria, and several other events on other axes. These doublets show significant correlation, and exhibit seismic phases traversing the Core that cannot be explained by a standard radial Earth model such as PREM. The antipodal waveform data are highly variable between axes. The observed variability of the waveforms indicates global variations in the structure above and below the Inner-Outer Core boundary region. We have found evidence for a regional low-velocity zone at the base of the Outer Core, corresponding with a decadal temporal variation (0.55 s) in seismic energy traversing the top of the Inner Core. We propose an antipodal seismic array to constrain and to provide further progress for the study of the Inner and Outer Core.