HELLENICHELLENIC ASTRONOMICALASTRONOMICAL SOCIETYSOCIETY PROCEEDPROCEEDINGSINGS 6th HELLENIC ASTRONOMICAL CONFERENCE Penteli, Athens, Greece, 15-17 September 2003 Sun and Heliosphere Stars & Stellar Systems Extragalactic Astronomy High Energy Astrophysics Cosmology, Relativity & Relativistic Astrophysics Galactic Dynamics & Chaotic Dynamical Systems Infrastructure of Astronomy in Greece History & Teaching of Astronomy Edited by PAUL G. LASKARIDES ATHENS March 2004 Proceedings of the 6th ASTRONOMICAL CONFERENCE of Hel.A.S. PUBLISHED BY The Hellenic Astronomical Society PRINTED BY The Editing Office of the University of Athens, Greece All rights reserved © 2004 Hellenic Astronomical Society No part of this material, protected by this copyright notice, may be reproduced or utilized in any form or by any means, electronic or mechanical including photocopying, recording or by any information storage and retrieval system, without written permission from the editor, or the President of Hel.A.S. Hellenic Astronomical Society e-mail: [email protected] ISBN 960-88092-0-7 Hellenic Astronomical Society (Hel.A.S.) Proceedings of the 6th ASTRONOMICAL CONFERENCE 15 – 17 September 2003, Penteli, Athens, Greece Edited by Paul G. Laskarides Athens 2004 COUNCIL OF Hel.A.S. Laskarides Paul, University of Athens (Chairman) Antonopoulou Eugenia, University of Athens (Vice Chairman) Tsinganos Kanaris, University of Athens (Secretary) Theodossiou Efstratios, University of Athens (Treasurer) Plionis Manolis, I.A.A. National Observatory of Athens Hatzidimitriou Despina, University of Crete Moussas Xenophon, University of Athens Scientific Organizing Committee P. Laskarides (Chairman, Univ.of Athens), S. Persides (Thessaloniki U.), C. Goudis (IAA- NOA & Patras U.), N. Kylafis (Crete U.), K. Tsinganos (Athens U.), I. Daglis (NOA Athens), K. Kokkotas(Thessaloniki U.), A. Mastichiadis (Athens U.), L. Vlahos (Thessaloniki U.), N. Voglis (R.C.A.A.M. Academy of Athens), E. Plionis (IAA-NOA Athens), E. Antonopoulou (Athens U.), M. Kontizas (Athens U.),D. Hatzidimitriou (Crete U.), E. Theodossiou (Athens U.), E. Danezis (Athens U.), M. Mathioudakis(Queens U., Belfast) P. Patsis (R.C.A.A.M. Academy of Athens) Local Organizing Committee from I.A.A. of the National Observatory of Athens C. Goudis (chairman) E. Kontizas, A. Dapergolas, I. Georgantopoulos, P. Boumis, E. Xilouris, I. Bellas-Velidis, N. Matsopoulos Sponsors: National Observatory of Athens University of Athens Achaia Clauss, Hewlett Packard Streamtrade K. Nomikos Municipality of Kalavryta Kalavryta Ski Centre This Volume has been published by the Editing Office of the University of Athens, a generous offer of the Vice-Rector of this University, Professor D. Asimakopoulos Preface The 6th Conference of the Hellenic Astronomical Society was held at the Penteli Astronomical station of the Institute of Astronomy and Astrophysics (IAA) of the National Observatory of Athens (NOA), from 15th to 17th of September 2003. This Conference was a high point in the history of Hel.A.S. since it was attended by the largest so far number of participants, especially young ones (graduate or undergraduate students of the Greek and foreign Universities). We all feel that their active participation guarantees the future of our Society. Also, a small number of internationally acclaimed invited speakers added their prestige to the very good work, as a whole, that was presented during the Conference by the Greek members of our Society and by their collaborators here and abroad. As you probably know, the financial situation of our Society did not permit the edition of the Proceedings and the plan was to have them posted on the electronic site of our Society as it was done with the 5th Conference. It was a pleasant surprise for all of us to hear the Vice-Rector of the University of Athens, Professor Demosthenis Asimakopoulos, during his official address, to promise the editing of the Proceedings by the Editing Office of the University of Athens. This offer made possible the printing of this volume and we all thank him for his offer. This surprise, however, brought some problems to us, since we were not prepared to collect the papers. The speakers were not ready (and some of them not even willing) to write a paper. So the initial deadline of November 15th was extended again and again in our desire to include as many papers in the proceedings as possible. The compilation of the volume was delayed even further since we had to deal with much different kind of files (some of them impossible to convert). I want to thank all of those who submitted their papers for publication. I am sorry that some of the speakers chose not to write one. For those, I have included in the Proceedings the abstracts they submitted before the Conference. As President of the Society, I take the opportunity to thank officially for one more time the members of the Scientific Organizing Committee, the members of the Local Organizing Committee as well as all the graduate students working in the I.A.A. of the N.O.A. and the clerks of this Institute for their contribution to the success of this Conference. Paul G. Laskarides Editor Penteli Station of the National Observatory of Athens β α The Hel.A.S. Invited Speaker Talks and the proceedings of half of the parallel sessions took place at the Visitors’ Center of the Institute of Astronomy and Astrophysics of the National Observatory of Athens (α) in the dome and under the operation plateau of the 26” Newall telescope (β). TABLE OF CONTENTS Author(s): Title Page Preface vii HELAS INVITED REVIEW E.N. Parker: Universal Magnetic Reconnection And Coronal Heating 1 SESSION I. THE SUN AND THE HELIOSPHERE Manolis K. Georgoulis: Statistical Properties of Flaring and Sub-Flaring Activity in the Solar 15 Atmosphere (Main Session Invited Speaker) C. Gontikakis, G. J. D. Petrie , H. C. Dara and K. Tsinganos: Study of a Solar Active Region Loop 25 Using EUV Spectra I.Zouganelis, N. Meyer-Vernet, M. Maksimovic and K. Issautier: Basic Aspects of the 30 Collisionless Kinetic Theory of the Solar Wind (Abstract) G.J.D. Petrie, C. Gontikakis, H.C. Dara, K. Tsinganos and M.J. Aschwanden: 2D MHD 31 Modelling of Heated Coronal Loops Compared to TRACE Observations S. Patsourakos and J. A. Klimchuk: Coronal Loop Heating by Nanoflares: Some Observational 35 Implications Z. Romeou and T. Neukirch: On the Application of Numerical Bifurcation Analysis Versus Linear 41 Stability Theory to Coronal Loop Equilibria Emmanuel T. Sarris and Olga E. Malandraki : Dependence of the Decay Phase of Solar Energetic 45 Electron Events on the Large-Scale IMFStructure: ACE Observations Isidoros Doxas: The Nonlinear Dynamics of the Magnetosphere and its Implications for Space 50 Weather Forecasting (Abstract) (Main Session Invited Speaker) K.Tziotziou, G.Tsiropoula , N.Mein and P.Mein: On the Nature of Chromospheric Umbral Flashes 50 And Running Penumbral Waves (Abstract) O. E. Malandraki, E. T. Sarris, P. Trochoutsos and G. Tsiropoula: Tracing the Magnetic Topology 51 of the July 2000 Coronal Mass Ejection Event at 62º South Heliolatitude By Means of ULYSSES/HI- SCALE > 38 KeV Electron Observations F.-A. Metallinou, I. A. Daglis, D. Delcourt and J.-H. Seiradakis: Transport and Acceleration of 56 Ions During Storm-Time Substorms (Abstract) M. E. Koukouli: An Unexplored Atmosphere; The Case of Venus in View of the Arrival of Venus 56 Express (Abstract) A.Daglis, Y. Kamide, D. Delcourt,and F.-A. Metallinou: The Role of Substorms in Ion Acceleration 57 during Geospace Magnetic Storms P. Tsitsipis, A.Kontogeorgos, C. Caroubalos, X. Moussas, C. E. Alissandrakis , A.Hillaris, P. 64 Preka-Papadema, J. Polygiannakis, J.-L. Bougeret, G. Dumas, C. Perche: Fine Radio Structures During a Major Solar Event Observed with Artemis IV (Abstract) G. Tsiropoula and K. Tziotziou: The Role of Spicules in the Mass Balance and Energy Budget of 64 the Solar Atmosphere (Abstract) A. Geranios , M. Vandas: Magnetic Clouds: A Subject of Space Weather Prediction 65 A.Anastasiadis, C. Gontikakis, N. Vilmer and L. Vlahos: Energetic Particle Acceleration and 71 Radiation in Evolving Complex Active Regions ABSTRACTS OF POSTER PAPERS P.K. Marhavilas, E.T. Sarris and G.C. Anagnostopoulos: Distinct Shock Acceleration Processes - 77 Evaluation of the Magnetic Trap Dimensions Formed Upstream of the Interplanetary Shock on 147 Day, 1991, Using Measurements of ULYSSES E. Mitsakou, C. Vassiliou, X. Moussas, J. Polygiannakis, A. Hillaris, P. Preka-Papadema, 77 Caroubalos, C., C. E. Alissandrakis, P. Tsitsipis, A. Kontogeorgos , J.-L. Bougeret, G. Dumas, C. Perche : Study of 40 Solar Energetic Events Based on GOES, LASCO and ARTEMIS IV Data (1998-2000) Angelos Vourlidas and Spiros Patsourakos: Solar Physics from Space for the Next Solar Cycle 78 J. M. Polygiannakis, A. Alevizos and X. Moussas: A Fluid Description of Directional Energetic 78 Particle Flux Observations G. Exarhos and X. Moussas: The Shape and Time Variations of the Heliosphere and Longterm 79 Modulation of Cosmic Rays N. Sergis and X. Moussas: The Northern Bow Shock and Electron Foreshock of Mars Based on 79 Mars Global Surveyor Data Georgiou M., Preka-Papadema P., Moussas X., Polygiannakis J. and Hillaris A.: Statistics on the 80 Occurrence of Solar Radio Bursts (Type IV and IV) and their Relation with CMEs and Flares Covering the Time Interval 1996-2001 (Rising and Maximum Phase of Solar Cycle 23) Pothitakis G., Preka-Papadema P., Petropoulos B., Moussas X., Polygiannakis J. and Hillaris, 80 A.: Study on the Spatial and Temporal Occurrence Rate of Hα Solar Flares and their Association with Halo CMEs during the Rising and Maximum Phase of the Solar Cycle 23 (1994- 2001) C. Caroubalos, X. Moussas, P. Preka-Papadema, A. Hillaris, I. Polygiannakis, H. 81 Mavromichalaki, C. Sarlanis, G. Souvatzoglou, M. Gerontidou, C. Plainaki, S. Tatsis, S.N.Kuznetsov, I. N. Myagkova and K. Kudela: Space Storm Measurements of 17 and 21 April 2002 Forbush Effects from Artemis-IV Solar Radio-Spectrograph, Athens Neutron Monitor Station and Coronas-F Satellite A.C.