Research Center for Astronomy


Thursday 8 September 2022, 11:00


Biophysical chaos: Bubbles in DNA molecules

Malcolm Hillebrand
Department of Mathematics and Applied Mathematics University of Cape Town


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Upcoming Workshop:


The Research Center for Astronomy and Applied Mathematics of the Academy of Athens (RCAAM), organizes on Friday, October 14th 2022, at the central building of the Academy of Athens (Panepistimiou 28), a one-day workshop on:

“Spirals and bars in galaxies”

The goal of the workshop is to bring together research experts working on the Dynamics and Morphology of disk galaxies to discuss current theories about the formation and evolution of the basic structures observed in this galactic type, namely the spirals and the bars. The scientific program consists of eight talks, which will be given by five invited speakers (E. Athanassoula, Laboratoire d’Astrophysique de Marseille (LAM), Marseille, France; C. Efthymiopoulos, Department of Mathematics, University of Padova, Italy; P. Grosbol, European Southern Observatory (ESO), Munich, Germany; T. Naab, Max-Planck Institut fuer Astrophysik, (MPA), Munich, Germany; K. Saha, Inter-University Centre for Astronomy and Astrophysics, Pune, India) and three RCAAM staff members (G. Contopoulos, P.A. Patsis, M. Harsoula). Discussions will follow all talks, as well as the end of the evening session.

Interested scientists may attend the event either in person (depending on the restrictions that may apply due to the pandemic) or over zoom, by joining the list of persons receiving the announcements of the RCAAM seminars at the web page .  In either cases they should send an e-mail to the organizers for approval (see contact details below). There are no registration fees.


Panos Patsis
Tel: +30-210-6597169





P.A. Patsis Welcome-Introduction to the workshop 9:30

G. Contopoulos:
Academy of Athens

The spiral arms of galaxies 9:45

K. Saha:
Inter-University Centre for Astronomy and Astrophysics, Pune, India

Revisiting spiral structures in galaxies 10:30

L. Athanassoula:
Laboratoire d’Astrophysique de Marseille (LAM), Marseille, France

Understanding the Formation and Evolution of Bars using Simulations


C. Efthymiopoulos:
Department of Mathematics,
University of Padova, Italy

Manifolds and spirals under multiple pattern speeds                           12:30
  Lunch Break  

P. Grosbol:
European Southern Observatory (ESO),
Munich, Germany

Interaction between spirals and bars in disk galaxies                          15:00

M. Harsoula:
Academy of Athens

The building blocks of the spiral arms in galaxies                               16:00

T. Naab:
Max-Planck Institut fuer Astrophysik, (MPA),
Munich, Germany

The formation of galactic star cluster populations                               17:00

P.A. Patsis:
Academy of Athens

Open questions about the association of observed structures and orbits in galactic disks                                                                                         18:00






Featured Picture


Gaflows in  barred galaxies with big orbital loops  

The gas response in a barred galaxy model, in which the orbital backbone of the bar, i.e. the orbits of the x1 family, have big loops close to the end of the bar, shows sevaral interesting features. In a recent study   (Pastras, Patsis, Athanassoula 2022)  we found that he dust-lane shocks in the gas responses of barred galaxies models avoid the regions in which the stable POs of the x1 family have developed sufficiently big loops. They deviate from these regions and, as they bypass them, they form extensions at an angle with the straight-line shocks. Ahead of them, in the direction of rotation, we find low-density regions, which in many cases have a “triangular”-like shape. We reach this conclusion by means of two conceptually different hydrodynamic schemes for our calculations, namely, the mesh-free Lagrangian SPH method and the adaptive mesh refinement code RAMSES. This allows us to compare responses by means of the two algorithms. 

 In the frame above, we present a typical snapshot of our RAMSES simulation, summarizing the main morphological features, together with the velocity vectors indicating the flow. The flow vectors are colored yellow, when they are in regions below the minimum density we considered. The two long white arrows indicate the point where the tails of the Γ features join the dust-lane shocks in the bar region. The stellar response is given in the background using a red color for the test particles. Red dots give the locations of the Lagrangian points.


View previous Featured Pictures here...

It is with deep sorrow that we inform you about the passing of our colleague and collaborator in RCAAM projects, Evangelos Chaliasos, last December.

Evangelos was born in Domianous Evritanias, Greece, on the 28th of December, 1947. He received his B.Sc. in Mathematics (1971) and in Physics (1979) from the University of Athens, Greece. He obtained a M.Sc. in Astronomy from the University of Chicago, U.S.A. (1988) and his Ph.D. from the University of Athens. His scientific interest was in relativistic Astrophysics.

New publication in Greek.

Latest Developments in Astronomy 2021: Research Results from the Research Center for Astronomy and Applied Mathematics of the Academy of Athens.

The Annual Report of our Center for 2021 is available in Greek  

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