Belgrade Astronomical Observatory Research Articles

Book Review: The Great Silence: Science and Philosophy of Fermi’s Paradox by Milan M. Ćirković

SETI, the Search for Extraterrestrial Intelligence, used to seem the cutting edge of available mystery. The Milky Way galaxy is immense, perhaps 400 billion stars, and the entire visible universe holds perhaps hundreds of billions of similar galaxies. If life on Earth is a product of evolution, there must be billions of billions of worlds inhabited by creatures ranging from bacteria to intelligent, conscious alien people, all distinct in form but converging on civilizations capable of listening for radio evidence of others near or preposterously far in space and time, and peppering the heavens with their own messages. If they are there, some nearby will have been able to pick up a century and more of electronic signals tearing out from our world at the speed of light. Yet we hear no faintest answer, no trace of them Out There. Why? Where are they? asked Nobelist Enrico Fermi in 1950, lunching with colleagues, toying with the mid-century hysteria over flying saucers. If our understanding of science is correct, “they” must be there, in profusion if not in UFOs. With this confidence in mind, SETI was established 35 years ago, nearly half a human lifetime, to listen and look for them. After the intervening decades, though, with ever-improving equipment, we still do not detect them. It’s a paradox! It’s “Fermi’s Paradox.” A Serbian astrobiophysicist and astronomer, Milan M. Ćirković, PhD, is a Senior Research Associate at the Astronomical Observatory of Belgrade and Assistant Professor of the Department of Physics at the University of Novi Sad in Serbia and Montenegro. On the evidence of this remarkable book, he is an ingenious polymath who shows little patience with SETI researchers who (he claims) fail to keep up with new data, displaying a kind of privileged narrow vision, or perhaps self-protection, in clinging to defunct theories of galaxies and their improbably absent inhabitants. Again, then: Where are they?

Aleksandar Kubicela (1930-2017): An astrophysical research pioneer at the Astronomical Observatory of Belgrade

Here, we give a short biography and summary of scientific contributions of Aleksandar Kubicela, a doyen of astronomy in Serbia, and an astrophysical research pioneer at the Astronomical Observatory of Belgrade. Additionally, we evoke some of our memories concerning scientific collaboration with Aleksandar Kubicela.

Digitization of the Belgrade Astronomical Observatory's vertical circle observational heritage

The aim of the paper is to present the digitization of the results of last observations of bright stars made by the Belgrade vertical circle ASKANIA N?80118 (D = 190 mm, f = 2578 mm) at the Astronomical Observatory of Belgrade. The observations are mainly made by Djuro Bozhichkovich in the period between 1982 and 1985. All of the found observational data and intermediary results are referenced and presented and some research possibilities are suggested.

Research of blazars at the Astronomical observatory of Belgrade

At the beginning of 2013, we have a team of scientists at the Astronomical Observatory of Belgrade, focusing on observations and research of blazars. At the same time, we established a cooperation with the Astronomical Observatory of Torino (Osservatorio Astrofisico di Torino), center for the Whole Earth Blazar Telescope (WEBT) international collaboration. In this paper, we describe the WEBT project, present our equipment as well as some preliminary results. We also point to some issues that we have encountered during the one year experience and found important from the observational point of view.

The STARK-B database as a resource for “STARK” widths and shifts data: State of advancement and program of development

“Stark” broadening theories and calculations have been extensively developed for about 50 years and can now be applied to many needs, especially for accurate spectroscopic diagnostics and modeling. This requires the knowledge of numerous collisional line profiles. Nowadays, the access to such data via an online database becomes essential. STARK-B is a collaborative project between the Astronomical Observatory of Belgrade and the Laboratoire d’Étude du Rayonnement et de la matière en Astrophysique (LERMA). It is a database of calculated widths and shifts of isolated lines of atoms and ions due to electron and ion collisions (impacts). It is devoted to modeling and spectroscopic diagnostics of stellar atmospheres and envelopes, laboratory plasmas, laser equipments and technological plasmas. Hence, the domain of temperatures and densities covered by the tables is wide and depends on the ionization degree of the considered ion. STARK-B has been fully opened since September 2008 and is in free access.The first stage of development was ended in autumn 2012, since all the existing data calculated with the impact semiclassical-perturbation method and code by Sahal-Bréchot, Dimitrijević and coworkers have now been implemented. We are now beginning the second stage of the development of STARK-B. The state of advancement of the database and our program of development are presented here, together with its context within VAMDC. VAMDC (Virtual Atomic and Molecular Data Center) is an international consortium which has built a secure, documented, flexible interoperable platform e-science permitting an automated exchange of atomic and molecular data.

Virtual Laboratory Astrophysics: the STARK-B database for spectral line broadening by collisions with charged particles and its link to the European project VAMDC

Atomic physics in plasmas has been an essential tool for many years. Accurate spectroscopic diagnostics and modeling require the knowledge of numerous collisional line profiles. "Stark broadening" theories and calculations have been extensively developed for about 50 years. Nowadays, the access to such data via an on line database becomes essential. The aim of STARK-B is to reply to this need. It is a collaborative project between the Astronomical Observatory of Belgrade (AOB) and the "Laboratoire d'Étude du Rayonnement et de la matière en Astrophysique" (LERMA) of the Paris Observatory and CNRS. It is a database of widths and shifts of isolated lines of atoms and ions due to electron and ion impacts that we have calculated and published in international refereed journals (more than 150 papers by Dimitrijević & Sahal-Bréchot, and colleagues). It is devoted to modeling and spectroscopic diagnostics of stellar atmospheres and envelopes, laboratory plasmas, magnetic fusion plasmas, laser equipments and technological plasmas. Hence, the domain of temperatures and densities covered by the tables is wide and depends on the ionization degree of the considered ion. The STARK-B database is in free access and is is a part of VAMDC: the Virtual Atomic and Molecular Data Centre is an European Union funded collaboration between groups involved in the generation and use of atomic and molecular data. VAMDC aims to build a secure, documented, flexible and interoperable e-science environment-based interface to existing atomic and molecular data. STARK-B and its VAMDC context are presented in this paper.

Virtual laboratory astrophysics : The STARK-B database

Stark broadening theories and calculations have been exten- sively developed for about 50 years. The theory can now be considered as mature for many applications, especially for accurate spectroscopic diagnostics and modelling. This requires the knowledge of numerous collisional line profiles, especially for very low abundant atoms and ions which are used as probes for modern spectroscopic diagnostics in as- trophysics. Nowadays, the access to such data via an on line database becomes essential. STARK-B (http://stark-b.obspm.fr )i s a col- laborative project between the Astronomical Observatory of Belgrade and the Laboratoire d'´ Etude du Rayonnement et de la matiere en Astrophysique (LERMA). It is a database of calculated widths and shifts of isolated lines of atoms and ions due to electron and ion col- lisions (impacts). It is devoted to modelling and spectroscopic diag- nostics of stellar atmospheres and envelopes, laboratory plasmas, laser equipments and technological plasmas. Hence, the domain of temper- atures and densities covered by the tables is wide and depends on the ionization degree of the considered ion. The STARK-B database is a part of VAMDC (Virtual Atomic and Molecular Data Centre, http:// www.vamdc.eu), which is an European Union funded collaboration be- tween groups involved in the generation and use of atomic and molec- ular data. VAMDC aims to build a secure, documented, flexible and interoperable e-science environment-based interface to existing atomic and molecular data.

Case studies on recent Stark broadening calculations and STARK-B database development in the framework of the European project VAMDC (Virtual Atomic and Molecular Data Center)

Stark broadening theories and calculations have been extensively developed for about 50 years. The theory can now be considered as mature for many applications, especially for accurate spectroscopic diagnostics and modelling. In astrophysics, with the increasing sensitivity of observations and spectral resolution, in all domains of wavelengths from far UV to infrared, it has become possible to develop realistic models of interiors and atmospheres of stars and interpret their evolution and the creation of elements through nuclear reactions. For hot stars, especially white dwarfs, Stark broadening is the dominant collisional line broadening process. This requires the knowledge of numerous profiles, especially for trace elements, which are used as useful probes for modern spectroscopic diagnostics. Hence, calculations based on a simple but enough accurate and fast method, are necessary for obtaining numerous results. Ab initio calculations are a growing domain of development. Nowadays, the access to such data via an on line database becomes crucial. This is the object of STARK-B, which is a collaborative project between the Paris Observatory and the Astronomical Observatory of Belgrade. It is a database of calculated widths and shifts of isolated lines of atoms and ions due to electron and ion collisions. It is devoted to modelling and spectroscopic diagnostics of stellar atmospheres and envelopes. In addition, it is relevant to laboratory plasmas, laser equipments and technological plasmas. It is a part of VAMDC (Virtual Atomic and Molecular Data Centre), which is an European Union funded collaboration between groups involved in the generation and use of atomic and molecular data.

The project of Serbian Virtual Observatory and data for stellar atmosphere modeling

We review recent developments in Serbian Virtual Observatory (SerVO) as well as developments surrounding Virtual Atomic and Molecular Data Center. Main components of SerVO are going to be the archive of photographic plates, database of Stark broadening parameters and stellar evolution database. Photographic plates were obtained at Belgrade Observatory from 1936 to 1996. Data for Stark broadening were obtained using semiclassical perturbation and modified semiempirical theories. Stellar evolution database is a mirror of Darthmouth evolution database with improvement and VO compatible outputs.

Deficit and surplus of precipitation as a continuous function of time

The quantitative measure of drought is a complex problem. A common factor in all types of drought is that they originate from a deficiency of precipitation. The difference between the real and potentially expected daily precipitation amount is what we have used to define the continuous function of daily deficit and surplus of precipitation (DSP). We have also defined the monthly and yearly DSP. We tested the precipitation data series for the normal climatic period 1961–1990 observed at the Meteorological Observatory of Belgrade. The DSP considers that the intensity of drought during the current period is dependent upon the current precipitation plus the cumulative precipitation of the previous period. When applied to longer periods, this function denotes dry and wet periods.

Hunt for Binaries with Pulsating Components

AbstractIn the frame of the collaboration of several Southern European observatories, we are examining a number of eclipsing binary systems in search for evidence of pulsating phenomena. We hope our candidate systems will be suitable for subsequent astroseismological studies. As a first step towards this end, we are analyzing spectroscopic observations of several such binary stars; these observations have been made at the National Astronomical Observatory Rozhen, Bulgaria, in the period from 2002 to 2005, and the reduction was done at the Astronomical Observatory of Belgrade, Serbia. The measurements of radial velocities and RV curve analysis are in preparation.

Program of telluric lines monitoring

A new observational program of telluric lines monitoring was introduced at Belgrade Astronomical Observatory. The ultimate goal of this program is to investigate the properties of Earth?s atmosphere through modeling the observed profiles of telluric lines. The program is intend to observe infrared molecular oxygen lines that were selected according to spectral sensitivity of the available CCD camera. In this paper we give the initial and the final selection criteria for spectral lines included in the program the description of equipment and procedures used for observations and reduction, a review of preliminary observational results with the estimated precision, and a short discussion on the comparison of the theoretical predictions and the measurements.

Characteristics of the Belgrade Astronomical Observatory's stellar spectrograph

In this paper the main features of the new SpectraPro-750 spectrograph of Belgrade Astronomical Observatory are described. The instrumental profile of the spectrograph for the 1200 l/mm grating is determined using a fiber optic bundle with fibers arranged in a pseudo-slit pattern. This instrumental profile is compared to the instrumental profiles obtained when the same fiber optic bundle illuminates the entrance slit with different widths. From appropriate instrumental profiles the practical spectral purities and the spectral resolutions for different entrance slit widths are obtained. The variation of the reciprocal linear dispersion with wavelength in the spectral range 350 - 600 nm is determined. A proposal for a link between telescope and the spectrograph is given.

Life and activities of Danilo Zulevic (1937 - 1998)

The life and scientific and professional activities of Danilo Zulevic (1937 - 1998), research fellow of the Belgrade Astronomical Observatory, are presented, followed by the Bibliography of his works, the list of bibliographical items wherein his name is mentioned and the list of his name?s citations in the Science Citation Index.

CCD astrometric observations of minor planets at the Belgrade observatory during 1999 (II)

76 precise astrometric positions of six observed minor planets (two NEO among them) are calculated. The SBIG ST-8 camera attached to Askania astrograph of Belgrade Observatory was used in the observations.

Micrometer measurements of double stars: Series 53

A set of 38 measurements of double stars, carried out with the Zeiss Refractor 65/1055 cm of the Belgrade Observatory, is communicated.

CCD astrometric observations of comets at the Belgrade observatory during 1998 - 2000 (I)

143 precise astrometric positions of seven comets were obtained with the CCD equipped Askania astrograph (13.5/160) of Belgrade Astronomical Observatory. The SBIG ST-8(1530 ? 1020 pixel array) camera was used in the observations.

Life and activities of Vasilije Oskanjan (1921-1989)

The life and scientific, professional and other activities of Vasilije Oskanjan (1921-1989), one-time director of the Belgrade Astronomical Observatory, research fellow of the Belgrade and Byurakan Observatories, are presented, followed by the Bibliography of his works, the list of bibliographical items wherein his name is mentioned and the list of his name?s citations in the Science Citation Index in the period 1946 - July 1999.

Life and scientific activity of Dusan Saletic (1927-1999)

Dusan Saletic, engineer-geodesist and colonel of the Yugoslav army, for many years an external collaborator of the Belgrade Astronomical Observatory had a prominent share in the accomplishment of some task concerning the problems of the positional astronomy. Presentation is here given of his activity and achievements in that field, along with the list of his published works.

Life and works of Milan Nedeljkovic (1857-1950)

Activities of Milan Nedeljkovic, the founder of Belgrade Astronomical Observatory and his published works are discussed. The Bibliography of his works, as well as a Bibliography of selected works on Milan Nedeljkovic, are enclosed.