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Start Over Subject space research

12. Chemical evolution of the galaxy and comets

Creator:
Vanýsek, V.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
space research, chemical evoluton, and comets
Language:
Czech
Description:
A possible influence of comets on the growth of heavy elements abundance suggested several years ago by Tinsley and Cameron is shortly reviewed. Such an effect would be significant if the formation of comets produce cometary material equivalent to 0.01 - 0.02 M per one solar mass. In the view of current hypothesis of the formation and structure of cometary nuclei the role of comets should be considered as one of the possible moderators of the Z value variation during the chemical evolution of our Galaxy.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

13. Dynamical evolution of star clusters and the possible disruption of globular clusters in M87 by massive black holes from a dark corona

Creator:
Wielen, Roland
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
space research, star clusters, and massive black holes
Language:
Czech
Description:
The dynamical evolution of star clusters is discussed. We investigate especially the possible disruption of globular clusters by massive black holes, which have been proposed as the major constituents of dark galactic coronae. As an example, we discuss here the globular clusters in the elliptical galaxy M87. The proposed massive black holes could be responsible for the observationally indicated depletion of the globular cluster system in the inner parts of M87 with respect to the stellar light distribution of this galaxy.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

14. Evolution equations for interplanetary dust

Creator:
Banaszkiewicz, M. and Kapišinský, I.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
space research, interplanetary dust, and kinetic equations
Language:
Czech
Description:
Kinetic equations for the distribution function of dust particles in mass and element spaces are formulated. Erosive as well as catastrophic collisions are taken into account. Sputtering is also included and radiative effects are considered. Initial conditions are derived from the Interplanetary Flux Model for mass distribution, and fan or cosine models for spatial density.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

15. Evolution of meteoroid streams

Creator:
Babadzhanov, P. B. and Obrubov, Yu. V.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
space research, meteoroid streams, and evolution of meteoroid streams
Language:
Czech
Description:
A meteoroid stream generally considered to be an elliptical ring of relatively small thickness. Such shape is attributable to meteoroid streams in an early stage of their evolution. Differences in planetary perturbations influencing the meteoroid particles ejected from the parent body from various points in its orbit at different velocities and time can result in a significant thickening of the stream. Our studies on the evolution of the short-period meteoroid streams have shown that these streams can produce several couples of showers active indifferent seasons of the year.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

16. Evolution of open clusters as N-body systems

Creator:
Terlevich, Elena
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
space research, open clusters, and N-body systems
Language:
Czech
Description:
Realistic N-body simulations of open clusters are discussed and compared with main observed cluster features. Most of the models have 1000 bodies with initial masses following a power law mass function of slope α = -2.75. Instantaneous mass loss from stellar evolution; a smooth linearized galactic tidal field and transient shocks by encounters with extended interstellar clouds of different mass-spectrum, density and space concentration are included. Close approaches between particles are treated by a two-body regularization technique that allows to follow binary evolution in detail. Good agreement is found between the distribution of lifetime for galactic clusters and the life of the models. It is found that the combined action of evolutionary mass loss and binaries (for 1000 star clusters with a realistic mass function) is enough to arrest the core collapse. Tidal heating shapes the halo of the cluster and produces a distinctive density and velocity distribution. Encounters with standard clouds do not alter the life-time of the clusters; while giant molecular clouds produce a catastrophic disruption. Mass segregation and preferential escape of light stars can account for the depletion of low luminosity stars in the better observed central region of clusters. Work on the primordial stages of evolution of clusters during star formation is reviewed, and linked to work on N-body clusters.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

17. Flat disk models-rotation curves and a new model for Milky Way

Creator:
Akyol, M. Ünal
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
space research, flat disk models for galxies, and Milky Way
Language:
Czech
Description:
Flat disk models for galaxies are studied on the basis of osscillations of distributed mass around equilibrium configuration. Convincing perspectives to existing galaxy types are available. Several kinds of galactic orbits are possible with peculiar rotation curves. Supersonic and very high velocities seem likely in the central region. Conventional rotation curve breaks into two, inner to the Solar circle and spiral arms. A new model for our galaxy is proposed.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

18. High velocity Herbig Haro objects near Cep A

Creator:
Lenzen, Rainer
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
space research, Cep A, and Herbig Haro objects
Language:
Czech
Description:
High proper motions of various Herbig Haro Object near Cep A are reported. For a distance of 725 pc we derive tangential velocities of 200 to 250 km/s which have their common origin near the compact HII regions 2 and 3. The resulting kinematic age is 1800 ±400 years. A weak, pointlike source (I = 20.6 mag) is detected at the position of the compact HII region 3a. No further source (I ≤ 23 mag) could be found in the region of radio continuum emission. However, an elongated feature of diffuse 1 μm emission is observed in line with the northern chain of compact radio knots. We conclude that a center of activity near the H2O-maser positions in HW2 and 3 is responsible for Cep A. It drives the molecular outflow, and also excites the compact radio continuum knots and surrounding HH-objects. The observed total luminosity and the 21 cm radio continuum data are consistent with B0.5V star or three B1V ZAMS stars.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

19. Investigation of the galactic rotation from the 21 cm line

Creator:
Petrovskaya, I. V.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
space research, galactic rotation, and 21 cm line profile
Language:
Czech
Description:
The maximum likelyhood method is used for study of galactic rotation which utilises the whole 21 cm line profile. The rotation curve is obtained in the region from R = 0.4 R, up to 2.3 R, and we do not find evidence for a fall-off bellow a flat rotation curve.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public