Science

 

Current research projects directed by and mostly carried out by the AOB staff financed by the Ministry of Science of Serbia for the period 2006-2010, withing a section of Astro and Geo Sciences, are the following:

146001 Influence of collisional processes on astrophysical plasma spectra - Stark broadening parameters for spectral lines significant for the investigations of astrophysical, laboratory, and technological plasmas, will be determined within the frame of the semiclassical perturbation, and other methods. When necessary, the lacking atomic data will be determined theoretically, using the SUPERSTRUCTURE code. -Obtained results will be used for investigation of the Stark broadening influence in stellar plasma, in stellar spectra modelling, and on the mode properties of hollow cathode excited noble gas mixture lasers. -Theoretical data and observations will be compared. -We will investigate the influence of collisional processes in stellar atmospheres with the formation of quasi molecular ion-atom complexes, involving Rydberg atoms and atoms in the ground state. - For investigation of Stark broadening, as well as for other collisional processes, for stellar atmosphere modelling and spectra synthesis, computer codes PHOENIX and SYNTH will be used. - We will work on the development of database BELDATA in which will be included obtained results, as well as on creation of two mirror sites, in Belgrade (BELDATA) and Paris (MOLAT). PI Milan Dimitrijević

146002 Astrophysical spectroscopy of extragalactic objects  - With investigations proposed in this project we are going to: - determine the physical and kinematical properties of the central part of AGN (from X-ray, UV, optical and radio spectroscopy) - investigate the influence of microlensing on spectra of images of lensed QSOs (in order to scan the innermost structure of QSOs and investigate structure of galaxies which are lens). - investigate the connection between stellar structure of AGN with the activity of the central part. - investigate the generation of gamma-ray bursts and their connections with microquasars We are going to develop new and apply already developed (from our group) models in order to explain the innermost structure of AGN, especially connection between different emitting regions (e.g. gamma, X-ray, UV, optical and radio emission regions). Also, we will use spectroscopic observations from databases (e.q. HST and SDSS archives). In order to complete the needed data for a sample of AGN and lensed QSOs we will propose observations, preferably with integral field spectroscopy. With these investigations we hope to give a contribution to the general view of active galactic nuclei and gravitational lensing phenomena. PI Luka Č. Popović

146003 Stellar and Solar Physics - Due to successful collaboration between projects Stellar Physics and Solar Physics in the past time period we join them now into a single project proposal for experimental and theoretical studies of stellar and solar plasmas. The observable details on the Sun help us to understand also stellar processes and vice versa. The main objectives of this project in the domain of stellar physics are the modeling and analysis of light and radial velocity curves in close binary systems (CBS) which will allow for reliable estimates of basic characteristics of stars, study of their activities, and study of physical and evolution processes. A special attention will be paid to CBS with active components (cool and bright spots, pulsations etc.), to systems in an intensive mass transfer phase between the components (with and without the accretion disk), and to the system mass loss etc. We plan to study light curves modulated by pulsations to examine stellar interiors by astroseismological methods. Spectral lines suitable for monitoring of solar irradiance variation and for solar plasma diagnostics will be studied both experimentally and theoretically. Theoretical studies will cover also problems concerning self-gravitational contraction of particle clouds, spectra of global solar pulsations, MHD waves and instabilities in non-uniform astrophysical plasma configurations. PI Gojko Đurašević

146004 Dynamics of Celestial Bodies, Systems and Populations - We study the dynamics of celestial bodies, systems and populations from the observational and theoretical points of view. We collect observations by means of several telescopes, reduce them and send the results to the international centers. Our theoretical investigations are characterized by the use of similar methods of data analysis and orbit determination, and of similar potentials. Development of new improved methods for the determination of orbits of asteroids and double stars and for the study of kinematics of stellar clusters and galaxies is intended to improve accuracy of the results and to ensure optimum performance of the next generation observational surveys. We study chaotic diffusion in the phase space of asteroid orbital elements and the conditions for the application of Nekhoroshev theorem; we continue with determination of their masses from mutual perturbations. Using the new orbits of double stars we derive masses of the components, parallaxes and absolute magnitudes; we construct velocity ellipsoids and study motion of galaxies in the local group. We expect to improve upon the amount and accuracy of observations and thus contribute to enlargement of the databases; to achieve better accuracy and efficiency of the methods of orbit determination; to grasp the very nature of motion of selected celestial bodies, systems and populations; to determine their physical properties; to improve our understanding of dynamical evolution over long time spans. PI Zorica Cvetković

146007 Inverse Problems in Astrophysics: Interferometry and Spectrophotometry of stars - A progressively increasing accuracy of observational data allowed recently some new problems in astrophysics to be treated as inverse problems. This project concerns new opportunities that became available with the advent of recent instruments and techniques in optical interferometry. In particular, the new generation of ground-based instruments for high angular resolution from infrared and visible interferometry will provide qualitatively new information for improving our understanding of stellar physics, through the comparison of observational results with the predictions of theoretical models of stellar interiors and atmospheres. However, with the classical array and/or earth rotation synthesis it will be possible to spatially resolve only a limited number of stars. On the other hand, the High Resolution Spectroscopy allows (through Doppler Mapping) indirect observational information on atmospheric structures of an unresolved star by modelling the observed flux distribution across the spectral lines. In this project we propose to study a selection of outstanding problems in stellar physics using the potential of new methods which combine the classical spectroscopy and Long Baseline Interferometry (particularly at VLTI), providing information that cannot be obtained otherwise with each of these techniques taken separately.  PI Slobodan Jankov

146012 Gaseous and stellar components of galaxies: interaction and evolution - We extend and generalize research hitherto performed within framework of the project on Structure, Kinematics and Dynamics of the Milky Way to the general issue of the stellar and gaseous components of galaxies in general, and their complex interactions. The main goals of this project are to model the interaction between intergalactic and galactic baryons in the context of both past history and predictions for the future evolution of galaxies. This is related to issues of the distribution of visible and dark matter, and notably on the dark matter stratification, where we shall work on the spectroscopic data gathered for a sample of early-type galaxies. Special attention will be paid to rates of supernovae, as a major factor regulating the interaction between gaseous and stellar components in normal galaxies, and properties of supernovae remnants, from which the history of such regulation can be inferred. We plan to study the effects of the declining star formation and SN rates on the properties of ISM in the framework of the nascent discipline of physical eschatology, dealing with the future evolution of astrophysical objects. Theoretical studies will also cover other aspects of physical eschatology such as the future evolution of CMB, limits on the evolution of structure and the information content of the universe, the problem of the arrow of time, as well as epistemological and methodological foundations of the extrapolation of current models into the cosmological future. PI Milan Ćirković

146016 Chemistry of Galactic and extragalactic molecular clouds - Many and abundant atypical terrestial isomers detected in the interstellar space, in molecular clouds, stress that the chemistry is not the usual one. In order to understand fully the processes in the ISM astronomical observations, and moreover interpretation of the data collected must be merged with appropriate chemical experiments and modeling. We propose a project where both Galactic and extragalactic molecular clouds will be studied, in order to identify chemical differences between systems of different metalicity. On the ‘ground’ a set of specially designed chemical experiments will be conducted in order to explain the observed and modeled data. In the Galaxy, our main interest is the problem of isomerisation in the ISM. Possible suitable candidates for both astronomical observations and chemical experiments are the molecules of hydrogen-cyanide and hydrogen-isocyanide. Radio-spectroscopy, and if appropriate IR spectroscopy, of selected molecular clouds and/or towards the background stars of the clouds will give a better constrained relative abundances of the isomers. The chemical experiment will concentrate mostly on the measuring of the branching ratio of the reactions which can produce both isomers. PI Silvana Nikolić

146022 History and epistemology of the natural sciences - The project includes researchers from the university and research centres who are engaged in study of history and epistemology of science of nature. It comprises those university staff whose primary research and pedagogical occupation is the history and philosophy of science, as well as those who are engaged in methodological and cognitive studies linked with their primary engagements in studying particular sciences. Researchers who are engaged in philosophy of science constitute the intelectual core of the project. Modern philosophy has to a large extent taken distance from both metaphysics and ideology. Its principal branch is the analytical philosophy, whose contribution to understanding and advances of scientific knowledge is highly valued in scientific communities. On the other hand those engaged in specific scientific research benefit considerably from an interaction with philosophy of science, whereas the dialogue between philosophy and creative science appears invaluable to modern philosophy. The proposed project is envisaged as a valuable forum for such a dialogue. PI

Acknowledgments: These abstracts (except for the P146022, courteously by Ms. V. Trajkovska) were provided by Ms. Andrijana Ivanović on behalf of Dr Ratko Jankov from Ministry of Science of Serbia.


In the year 2001 the public financing of science in Serbia changed from awarding a total of a research fund to a whole institute to directly funding specific research projects of smaller group of scientists, employed in the same or different research institutes or faculties/universities in Serbia. Following this scheme the projects directed by the AOB staff and finished in 2005 were: