Magda Stavinschi

On the Schwarzschild-Type Polygonal ( n + 1 ) - Body Problem and on the Associated Restricted Problem

The planar symmetrical (n-fl)-body problem in a Schwarzschild-type field is being investigated. One proves that, if η equal masses are initially situated at the vertices of a regular polygon centered in the (n+l)th mass, and if the initial velocities form a vector field symmetrical with respect to the central mass, then the polygonal configuration is preserved all along the motion, but with variable side and with variable rotation around the center. The motion of every mass relative to the center is given by the solution of the Schwarzschild-type two-body problem. All possible behaviors of the polygonal solution are surveyed. In the second part of the paper, the relative equilibria of the (n+l)-body problem are pointed out. One associates a restricted problem to them, for which the Jacobi integral is proved to exist.

The Anisotropic Schwarzschild-Type Problem, Main Features

The two-body problem associated to an anisotropic Schwarzschild-type field is being tackled. Both the motion equations and the energy integral are regularized via McGehee-type transformations. The regular vector field exhibits nice symmetries that form a commutative group endowed with an idempotent structure. The physically fictitious flows on the collision and infinity manifolds, as well as the local flows in the neighbourhood of these manifolds, are fully described. Homothetic, spiral, and oscillatory orbits are pointed out. Some features of the global flow are depicted for all possible levels of energy. For the negative-energy case, few things have been done. The positive-energy global flow does not have zero-velocity curves; every orbit is of the type ejection – escape or capture – collision. In the zero-energy case, the collision and infinity manifolds have a very similar structure. The existence of eight trajectories that connect the equilibria on these manifolds is proved. The projectability of the zero-energy global flow completes the full understanding of the problem in this case.

Binary collisions in quasihomogeneous fields

Abstract The quasihomogeneous fields (featured by sums of homogeneous potentials) model a lot of concrete fields met in problems of nonlinear particle dynamics. The particularly important case of binary collisions in such fields is tackled, and the local behaviour of the corresponding solutions is fully understood.

Big questions about the universe

Astronomy is not only a branch of science but also an important part of the culture and civilisations of peoples. Starting with archeoastronomy to the present day, it has always contributed to a better understanding of life, of humanity. After 400 years of modern astronomy, it still addresses major problems such as: Why there is something rather than nothing? Why is nature comprehensible to humans? How is cosmos related to humanity? Do multiverses exist? Is there life on other planets? Are we alone in the universe? Does the universe have a beginning? If so, what does it mean? How did the universe originate? All these questions are a challenge for interdisciplinary and transdisciplinary investigations, for philosophers, physicists, cosmologists, mathematicians, theologians. The new insights gained by pursuing in depth these common investigations will shape the society we live in and have important consequences on the future we are creating.

A Long Journey of Mathematics and Astronomy in Romania

Bucharest Astronomical Observatory celebrated recently its centenary. Its founders were all mathematicians or, better said, astronomers specialized in celestial mechanics. Their first doctoral theses were defended at Sorbonne, in the second half of the 19th century, under the guidance of the greatest specialists of the time. After they returned home, they continued what they had begun in Paris, namely celestial mechanics. The instruments they ordered and the first programmes of astronomical observations had an increasingly closer relation to mathematics, as they referred to astrometry and especially to stellar catalogues.Naturally, there were also astrophysical concerns, timid ones in the beginning, and then ever larger, especially beginning with the International Geophysical Year.The evolution of world astronomy, as well as that of Romania, seems to be following but one direction: astrophysics. The truth is that astrometry and celestial mechanics continue to lie at the basis of all astrophysical research...

Astronomical Heritage, an important tool for education

The sky and its lore have been always a historical heritage common to all the peoples and thus must be considered as an important cultural element. The European Union Institutions have considered a significant issue locating, studying and keeping for the future the historical places that have had an astronomical cultural relation, considering the information about the sky as a natural and cultural relation that has to be preserved.

DIVISION I / WORKING GROUP ASTROMETRY BY SMALL GROUND-BASED TELESCOPES

At the IAU XXVI General Assembly in 2006, the Division I decided to create the Working Group on Astrometry by Small Ground-Based Telescopes (WG-ASGBT). Its scientic goals are to foster the follow-up of small bodies detected by the large surveys including the NEOs; to set-up a dedicated observation network for the follow-up of objects which will be detected by Gaia ; to contribute to the observation campaigns of the mutual events of natural satellites, stellar occultations, and binary asteroids; and to encourage teaching astrometry for the next generation. The present report gives the main activities carried out in these areas with small telescopes (diameter less than 2m).

100 Years and More of Romanian Astronomy

We present a brief history of the Romanian astronomy. We focus on the Bucharest Astronomical Observatory, presenting its set up and its development, with all difficulties and successes. The research after 1990, under the aegis of the Astronomical Institute of the Romanian Academy, is emphasized.

Moments of astronomy education in Bucharest

Selection from past astronomy education, activities, textbooks and curricula will be presented. Didactic aspects and comparison with physics education will be exemplified. The astronomy/science education along the time in Romania was roughly divided in four directions: very broad information texts for everybody, popular science, school textbooks, science fictions and astronomy/science literature, and exemplified using original texts. All categories were intended to extend literacy in science, but in different ways. The trends for different periods were outlined. The teaching of astronomy and astrophysics in high school and universities, with special attention to the Faculty of Physic from University of Bucharest are presented. Suggestions for future improvement of both related fields, physics and astronomy, will be one of the outcomes of our communication.

Bucharest‐Nikolaev Astronomical Observatories’ Collaboration in Astronomy

Scientific collaboration between Bucharest Observatory of the Astronomical Institute (Romania) and Nikolaev Astronomical Observatory (Ukraine), based on the similar research directions and scientific traditions from the beginning of 1990s. The main research field was positional astronomy with compilation of catalogues of star positions in the fields around selected ERS from the CCD observations in Nikolaev and photographical observations in the Bucharest Observatory. Many conferences and workshops, mutual visits of astronomers from both observatories were organized and held in Nikolaev and Bucharest.