Meteor stream membership criteria us ed in evaluating potential associations between individual meteor orbits and the mean orbit of a stream are discussed on the basis of precise photographic orbits of some meteor streams (the Taurids, Geminids and Perseids). Serious shortcomings of the D-criterion are disclosed and suggestions on a more relevant use of the criteria for estimating stream memberships are presented, with attention paid to the distributions of the orbital elements of the streams.
The data processing unit within the framework of the Intershock project is a general-purpose computer modified to be installed onboard the satellite. The instrument inputs have analog digital and impulse sensors. it generates digital arrays to be stored in a
long-time memory (LTM). The data processing unit´s operations are functionally determined by programs stored in the processor memory. In this specific case the instrument is intended for a comprehensive study of the structure of shock waves in the space plasma. The instrument has a reprogramming system which can make onflight changes in the instrument´s scheduled operations so that the instrument can solve a different problem which conforms with the instrument capabilities and the software used.
High-dispersion CaII and K, CaII IR 18542 A, Hα, Hβ, and D, emission line profiles of quiescent prominences have been recorded in Stará Lesná Observatory. After data reduction, a full set of calibrated profiles is used to discuss semiempirical non-LTE prominence models.
Improving precious studies based on galaxies belonging to various aggregations, our examination of the radio and optical properties of Virgo spirals indicates that the ratio of the radio continuum-to-optical luminosiy of spirals is linked to their HI content. Specifically, HI deficient spirals tend to be weaker radio continuum emitters.
Mechanisms leading to higher particle concentrations in several places along the meteor stream associated with comet Halley are discussed. The positions of the mass concentrations represented by the mean anomaly of the stream orbit, as determined from long series of observations of the Orionids and Eta Aquarida, are correlated with the deviations in the semi-major axis and nodes of the evolving orbit of the comet. It is shown that random deviations in the orbital elements of the comet may be responsible for the nonstable mass concentrations in the stream.
Účelem každoroční mezinárodní konference o optice pro rentgenovou astronomii AXRO (International Workshop on Astronomical X-Ray Optics) jsou přednášky a následné diskuse o technologiích pro astronomická pozorování v rentgenovém oboru spektra. Sympozium, které se konalo 8.-11. prosince 2014 v pražské vile Lanna za účasti 40 odborníků z EU, USA, Ruska, Číny, Saúdské Arábie a Japonska, prokázalo důležitost propojování základního a aplikovaného výzkumu. AXRO 2014 uspořádaly Astronomický ústav AV ČR, České vysoké učení technické v Praze a Ministerstvo dopravy ČR. and Vojtěch Šimon.
This review is devoted to discuss our present understanding of how outflows participate in defining ths various types of morrphologies and featurea observed in Active Galactic Nuclei (AGN). We suggest possÍble interpretations of structurcs observed at radio frequencies (non-thermal continuum radiation) and optical frequencies (continuum and emission line radiation) in terms of results from numerical simulations of outflow propagation and their analytical physical explanation. The conclusion is that we have already reached a good qualitative knowledge oř the several dynamical effects which shape AGN’s structures; the quantitative estimate of their relative importance and conditions of occurrence still awaits a better study of the nonlinear processes in astrophysical conditions and more observational data to determine the values of the physical parameters.
All known groups of fireballs contain bodies which may reach the Earths surface as meteorites and are of planetary origin. Since some fireballs have cometary orbits in the Solar System, then comets are probably of planetary origin. The possible explosion
of a large planet is discussed again. This time on the basis of gravitationally decelerated expansion of an originally superdense embryo.
For the first time, scientists have observed ripples in the fabric of space time called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein´s 1915 general theory of relativity and opens an unprecendented new window onto the cosmos. Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. Physicists have concluded that the detected gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole. This collision of two black holes had been predicted but never observed. The gravitational waves were detected on September 14, 2015 at 09.51 UTC by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA. The discovery was made by the LIGO Scientific Collaboration (which includes the GEO Collaboration and the Australian Consortium for Interferometric Gravitational Astronomy) and the Virgo Collaboration using data from the two LIGO detectors. Special prominence is given to this topic in the article by Dr. Vladimír Wagner of the Nuclear Physics Institute of the CAS. and Vladimír Wagner.