High resolution (0.C5 A) spectra are used for the determlnatlon of the profiles of the diffuse Interstellar bands 5780 and 5797 orlginatlng in single clouds. It is shown that some of the clouds may contain agents of certain diffuse bands whereas others may not. The proflles of diffuse bands observed in dlstant stars contaln contributions from several clouds, differing In optical properties, which share the Doppler displacements observed in interstellar sodium lines. The Doppler splitting inside the diffuse bands´ profiles is, however, efficlently veiled because of the large intrinslc widths of the bands under consideration.
I review our series of works on the galactic evoluton putting emphasis on some fundaments of he models instead that on their detailed structure. I show, with some example how the mathematical formulation is produced from the physical input, how it can be modified as physics is enriched, and which kind of results can be provided.
I review some aspects of recent studies of active galactic nuclei (AGN) and their environments. My approach is from the hypothesis that a single AGN phenomenon includes the plethora of object classes whose acronyms pervade the literature. Particular attention is given to the mechanisms of interaction between the cetral engine and its environment, both with regard to the ways in which the observed radiation is produced on a range of spatial scales and to the ways in which the activity is related to outside influences.
Adaptavní optické systémy se vyznačují schopností měnit své optické vlastnosti na požádání a v reálném čase. V tomto příspěvku jsou diskutovány základní prvky adaptivních optických systémů využívaných v astronomii ke kompenzaci vlivu atmosféry na zobrazení velkých pozemských teleskopů., Adaptive optical systems are those whose optical responses can be adjusted on demand, in real time. Here we discuss the basics of adaptive optical systems utilised in astronomy for compensation of aberrations due to atmospheric turbulence, which seriously impairs the performance of uncorrected large ground-based telescopes., Jaroslav Řeháček, Bohumil Stoklasa., and Obsahuje seznam literatury
We have reported elsewhere the discovery of apparently
high-degree nonradial oscillations for the four rapidly rotating (-120 kms^-1) δ Scuti stars: 21 Mon, κ^2 Boo, ν UMa, and o Eri. Here we discuss some of the techniques which we have used to isolate and to analyse the time varying components (-1% continuum) of the line profiles. They are best seen after subtraction of an average, filtered spectrum. For the δ Scuti stars, periodograms of the residual spectra show several peaks, some of which can be identified with the degrees of oscillation found in our preliminary analysis. In the latter, values of |m| were estimated from the sub-feature accelerations and delay in transit of the features. While one mode tends to dominate it is clear that often more than one Is present. The sub-features are not always equally spaced and they can show phase changes and doubling. While nrp provides an adequate, general description of the phenomena, we are probably seeing only part of something more complex. The immediate challenge is to combine the results from many lines plus higher spectral resolution to improve the visibility of the time varying features by at least an order of magnitude.