Compact Groups of Galaxies in the Las Campanas Redshift Survey

We have recently extracted a catalog of compact groups of galaxies (CGs) from the Las Campanas Redshift Survey. This catalog of Las Campanas Compact Groups (LCCGs) contains 76 CGs with a median redshift of z_med = 0.08. The physical properties of these CGs are similar to those from the Hickson (1982) and the Barton et al. (1996) catalogs. Here, we present an atlas of our catalog and briefly describe its general properties.Comment: 10 pages, 4 figures, 3 tables. Figure 4 is broken up into four gif files. Paper accepted by "Astronomische Nachrichten: News in Astronomy and Astrophysics.

Alfven Wave Generation by means of High Orbital Injection of Barium Cloud in Magnetosphere

An analysis of the Alfven wave generation associated with the barium vapor release at altitudes ~ 5.2 Earth's radii (ER) in the magnetosphere is presented. Such injections were executed in G-8 and G-10 experiments of the Combined Radiation and Radiation Effects Satellite (CRRES) mission. It is shown that the generation of Alfven waves is possible during the total time of plasma expansion. The maximum intensity of these waves corresponds to the time of complete retardation of the diamagnetic cavity created by the expansion of plasma cloud. The Alfven wave exhibits a form of an impulse with an effective frequency ~ 0.03-0.05 Hz. Due to the background conditions and wave frequency, the wave mainly oscillates along the geomagnetic field between the mirror reflection points situated at ~ 0.7 ER. The wave amplitude is sufficient to the generation of plasma instabilities and longitudinal electric field, and to an increase in the longitudinal energy of electrons to ~ 1 keV. These processes are the most probable for altitudes ~ 1 ER. The auroral kilometric radiation (AKR) at frequencies ~ 100 kHz is associated with these accelerated electrons. The acceleration of electrons and AKR can be observed almost continuously during the first minute and then from time to time with pauses about 35-40 s till 6-8 min after the release. The betatron acceleration of electrons at the recovery of the geomagnetic field is also discussed. This mechanism could be responsible for the acceleration of electrons resulting in the aurorae and ultra short radio wave storm at frequencies 50-300 MHz observed at the 8-10th min after the release.Comment: Presented at COSPAR 200

Ionospheric phenomena before strong earthquakes

A statistical analysis of several ionospheric parameters before earthquakes with magnitude <i>M</i> <u>></u> 5.5 located less than 500 km from an ionospheric vertical sounding station is performed. Ionospheric effects preceding &quot;deep&quot; (depth <i>h</i> > 33 km) and &quot;crust&quot; (<i>h</i> <u><</u> 33 km) earthquakes were analysed separately. Data of nighttime measurements of the critical frequencies <i>fo</i>F2 and <i>fo</i>Es, the frequency <i>fb</i>Es and Es-spread at the middle latitude station Dushanbe were used. The frequencies <i>fo</i>F2 and <i>fb</i>Es are proportional to the square root of the ionization density at heights of 300 km and 100 km, respectively. It is shown that two days before the earthquakes the values of <i>fo</i>F2 averaged over the morning hours (00:00 LT–06:00 LT) and of <i>fb</i>Es averaged over the nighttime hours (18:00 LT–06:00 LT) decrease; the effect is stronger for the &quot;deep&quot; earthquakes. Analysing the coefficient of semitransparency which characterizes the degree of small-scale turbulence, it was shown that this value increases 1–4 days before &quot;crust&quot; earthquakes, and it does not change before &quot;deep&quot; earthquakes. Studying Es-spread which manifests itself as diffuse Es track on ionograms and characterizes the degree of large-scale turbulence, it was found that the number of Es-spread observations increases 1–3 days before the earthquakes; for &quot;deep&quot; earthquakes the effect is more intensive. Thus it may be concluded that different mechanisms of energy transfer from the region of earthquake preparation to the ionosphere occur for &quot;deep&quot; and &quot;crust&quot; events

On the possible influence of radon and aerosol injection on the atmosphere and ionosphere before earthquakes

International audienceA model of the generation of pulses of local electric fields with characteristic time scales of 1?10 min is considered for atmospheric conditions above fracture regions of earthquakes. In the model, it is proposed that aerosols, increased ionization velocity and upstreaming air flows occur at night-time conditions. The pulses of local electric fields cause respective pulses of infrared emissions. But infrared emissions with time scales of 1?10 min were not observed up to now experimentally. The authors think, that the considered non-stationary field and radiation effects might be a new-type of applicable earthquake indicators and ask to perform special earth-based and satellite observations of the night-time atmosphere in seismoactive fracture regions

Daytime variations of foE connected to earthquakes

Abstract. In the present work it is shown that, in accordance with the observations of the vertical sounding station "Tashkent", the critical foE-frequency of the daytime E-layer increases about one day before winter-earthquakes with magnitudes M > 5 and depths of the epicentre of h < 60 km, which appeared at distances of R < 2000 km from the station. The reliability of the result is larger than 99 %. The phenomenon is not observed for summer-earthquakes. It seems to be determined by the atmospheric wind system. Further, the variations of the foE-frequency are compared with possible simultaneous variations of the critical frequency foF2 of the F2-layer. First results show that only very large changes of the ionisation density in the E-layer influence the ionisation density in the F-region. Therefore, no synchronous growth of the foE- and foF2-frequencies 1–2 days before seismic shocks could be observed

IR spectral analysis for the diagnostics of crust earthquake precursors

Some possible physical processes are analysed that cause, under the condition of additional ionisation in a pre-breakdown electric field, emissions in the infrared (IR) interval. The atmospheric transparency region of the IR spectrum at wavelengths of 7–15 μm is taken into account. This transparency region corresponds to spectral lines of small atmospheric constituents like CH&lt;sub&gt;4&lt;/sub&gt;, CO&lt;sub&gt;2&lt;/sub&gt;, N&lt;sub&gt;2&lt;/sub&gt;O, NO&lt;sub&gt;2&lt;/sub&gt;, NO, and O&lt;sub&gt;3&lt;/sub&gt;. The possible intensities of the IR emissions observable in laboratories and in nature are estimated. The acceleration process of the electrons in the pre-breakdown electrical field before its adhesion to the molecules is analyzed. For daytime conditions, modifications of the adsorption spectra of the scattered solar emissions are studied; for nighttime, variations of emission spectra may be used for the analysis

On variations of <i>fo</i>F2 and F-spread before strong earthquakes in Japan

International audienceThe statistical analysis of the variations of the dayly-mean frequency of the maximum ionospheric electron density foF2 is performed in connection with the occurrence of (more than 60) earthquakes with magnitudes M>6.0, depths hRfoF2 decreases before the earthquakes. One day before the shock the decrease amounts to about 5%. The statistical reliability of this phenomenon is obtained to be better than 0.95. Further, the variations of the occurrence probability of the turbulization of the F-layer (F spread) are investigated for (more than 260) earthquakes with M>5.5, hRfoF2 analysis, the Wolf number is less than 100 and the index SKp is smaller than 30, and in case of the F-spread study a Wolf number less than 80 and SKp smaller than 17 are chosen

Day-time variations of foF2 connected to strong earthquakes

Abstract. The statistical analysis of the characteristic frequency foF2 of the Earth's ionosphere averaged over mid-day hours – from 11:00 till 17:00 h LT – is carried out. Disturbances of foF2 connected to earthquakes are considered on the background of seasonal, geomagnetic, 11-years and 27-days solar variations. A special normalized parameter F is introduced, which represents the almost seasonal-independent part of foF2. Days with high solar (Wolf number >100) and geomagnetic (∑Kp>30) activity are excluded from the analysis. Events with magnitude M>5, distance from the sounding station R5.5. The obtained phenomenon depends on the magnitude of the earthquake. For events with M>5.5, the reliability of the effect is larger than 95%. For data of more than 80 earthquakes in the vicinity of Petropavlovsk-Kamchatsky and more than 200 earthquakes in the vicinity of Tokyo analogous results are obtained