INAF Osservatorio Astrofisico di Catania

Transcription

1 INAF Osservatorio Astrofisico di Catania Annual Report 2003 June, 30 th 2004

2 INAF - Osservatorio Astrofisico di Catania Città Universitaria Via Santa Sofia 78 I Catania (Ct) Phon / Fax URL Mario Girolamo Fracastoro Mountain Station Contrada Serra la Nave (Mt. Etna) Ragalna (Ct) Altitude: 1725 m; Longitude: +14 o 58.4 ; Latitude +37 o 41.5 Phon Edited by: G. Catanzaro, M. P. Di Mauro and S. Messina Printed: June 30 th, 2004 Cover: M. G. Fracastoro Mountain Station, night view of the 61cm telescope dome

3 Contents Foreword Osservatorio Astrofisico di Catania: Staff directory 2003 xi xiii 1 OACt 2003 Summary/Highlight 1 2 Research Solar Physics Systematic patrol of photospheric and chromospheric activity Spectroscopic diagnostic and modelling of coronal structures Energetic events in the solar atmosphere: flares and eruptive prominences Emergence and evolution of solar active regions Sunspots rotation Irradiance variation of the Sun Internal structure and helioseismology Conferences, Meeting and Ph. D. Committes Stellar physics Magnetic activity and variability Magnetic structures in the photospheres, chromospheres and coronae of single stars and close binary systems Structure and modelling of the stellar chromospheres and coronae Orbital period modulation and magnetic activity cycles in close binaries Evolution of stellar magnetic activity and related phenomena Systematic observations and activity cycles Dynamo theory of stellar magnetic fields Stellar oscillations and asteroseismology Solar-type stars Asteroseismology of hot subdwarf stars Conferences and Meetings Committes Chemical composition studies and chemically peculiar stars Magnetic Field Chemical Abundances Spectrum variability Search for brown dwarfs iii

4 iv CONTENTS Nuclear astrophysics Search for extra-solar planets Radial velocity exo-planet search Modelling stellar magnetic activity for planetary transit search Extra-galactic Astrophysics and Cosmology Extra-galactic Astrophysics Observations of BL Lac objects Gamma Ray bursts observation Hot stars in Local Group galaxies Cosmology and Large Scale Structure of the Universe Formation and Evolution of Substructures and Minihalos Mechanical heating of the Intergalactic Medium Cosmology and Particle Physics Laboratory of experimental astronomy and Solar System physics Background Experimental facilities The vacuum chamber The ion implanter Upgrade and calibration of the ion implanter The UV lamp Infrared transmittance and reflectance spectroscopy Raman spectroscopy Photo and ion luminescence Results Ion irradiation and UV photolysis of ices Nitrogen condensation on water ice C 70 fullerene Carbon and nitrogen implantation on icy surfaces Frozen hydrocarbons Evolution of the surface materials on Trans Neptunian Objects: the role of ion irradiation Understanding the origin of the interstellar 3.4 µm band: new laboratory striking results Asteroids photometry On going research Workshops and meetings Catania astrophysical Observatory Laboratory for Detectors (COLD) Detectors CCD controllers CVD Diamonds detectors SPAD detector Telescopio Nazionale Galileo Maintenance and upgrade of TNG CCD controllers Development and maintenance of TNG user interfaces Participation in National and international projects Eddington project

5 CONTENTS v XSHOOTER Spectrograph The CCD cameras for Catania Astrophysical Observatory CCD camera for the Schmidt telescope CCD camera for the 91 cm telescope Support to solar and stellar observations Collaboration with Industries Computational technologies for astrophysics Introduction FLY. A parallel tree N-body code for cosmological simulations. A Public Domain code Scientific Visualization Basic Functionalities Data Analysis Functionalities Grid Computing Astrocomp Future development The digitation of the archive of astronomical plates of Catania Astrophysical Observatory Projects and Collaborations National and international projects Collaborations Facilities and Services Buildings Acquisition of new instrumentation and facilities Library Computing Center and local network Opto-mechanical workshop and telescopes automation Telescope automation Opto-mechanical laboratory CCD image acquisition Photometric data acquisition and reduction The Mario G. Fracastoro station on Mt. Etna Solar observation facilities Out-reach and Education Out-reach Office Public conferences Visits to the Observatory Special events University Courses and high level Educational Activity Ph.D. Students Staff members Staff on 31 December

6 vi CONTENTS List of Publications Refereed papers Refereed papers in press Edited volumes (proceedings) Invited talks and reviews Invited talks and reviews in press: Contributions to international conferences Contributions in press Presentations without proceedings Electronic publications, short articles and technical reports A Sommario del bilancio OACt

7 List of Tables 1 Catania Astrophysical Observatory, /phone directory xvi 2.1 Spot parameters obtained from model solutions MG Fracastoro station: Telescopes activities A.1 Entrate (keu) A.2 Spese (keu) vii

8 viii LIST OF TABLES

9 List of Figures 2.1 Distribution of data and international cooperations involving the solar observations carried out in Catania Image of the extended solar corona obtained by the LASCO C1 coronagraph on October 30, Observations of reconnection phenomena acquired by THEMIS A prominence eruption observed by TRACE Reconstruction of evolutionary phases of a recurrent active region (NOAA 10050) obtained from the images acquired by THEMIS telescope Variaton of a sunspot groups angular velocity during the activity cycle Multi-band best fit to the Total Solar Irradiance (TSI) and the Solar Spectral Irradiances (SSI) in the three optical bands Helioseismic inversion to probe Newton s gravitational constant Maximum-Entropy-regularized images reconstruction for the components of HR D mapping of the photospheric and chromospheric inhomogeneities in HK Lac Hβ and Hei D 3 chromospheric and TR diagnostics in HD Plots of interesting portions of the α Cen A HST/STIS and SOHO/SUMER quiet sun The differential emission measure distribution of α Cen A is compared with corresponding distributions for the quiet and active Sun log (L X /L bol ) vs. A max for F-M stars Power law fits to the log (L X /L bol ) -A max relation The expected relative orbital period variation of a star-planet system versus the orbital period of the planet according to the model by Lanza & Rodonò (1999) Connection between orbital period modulation and magnetic activity in the prototype eclipsing binary RS CVn (top panels) Long-term V-band brightness variations of BE Cet (left)) and DX Leo (right). (bottom panel) Seasonal rotation periods vs. time with a linear fit to data. The rotation period monotonically decreases along the starspot cycle showing a solar-like behaviour for BE Cet (left) and anti-solar for DX Leo (right) (left panel) The rotational period variations ( P) are plotted vs. the mean rotational period. (right panel) The cycle frequency (ω cyc ) is plotted vs. the relative surface differential rotation amplitude ( Ω/Ω) ix

10 x LIST OF FIGURES 2.20 Li i equivalent width of some PMS candidates plotted as a function of (B V ) 0 color index Evolution tracks identifying η Boo as being in the post-main-sequence phase Evolution tracks identifying η Boo as being in the main-sequence phase Radial velocity curve measured for Procyon Power spectrum of oscillations measured in Procyon Fei lines of HD Effective magnetic field of β Lyrae FUSE spectrum of HD modeled Comparison between the observed and computed H δ and H γ lines in HR The amplitude spectra for the effective magnetic field strength variation in γ Equ Equivalent width variations of HD and HD Fitted spectral regions of the SB2 system HD Radial velocity curve of HD and composite Hβ profile of HD Effects of stellar magnetic activity on planetary transit detection Normalized spectra of stars observed in M Output of the Cineca Key Project simulation at z= Accretion shock in the Intergalactic Medium around a Dark Matter halo moving at speed v halo = 2c sound Astrophisycs Laboratory: Apparatus Astrophisycs Laboratory: Possible experiments Astrophisycs Laboratory: Upgraded implanter Astrophisycs Laboratory: Photolysis/irradiation of H 2 O Astrophisycs Laboratory: Evolution for hydrogenated carbon grains in ISM The 5 2 CVD diamond matrix The CCD camera for the Schmidt telescope mounted at Cima Ekar The prototype of the CCD camera for the 91 cm telescope (left panel) IBM SP (right panel) IBM p650 Series Simulation of formation of clusters of galaxies in the universe: user interface Simulation of formation of clusters of galaxies in the universe: texture mapping and ray tracing technique The Astrocomp Portal ( Library historical section, Agelli (1718) Library historical section, Newton (1760) The 91-cm Cassegrain reflector with fibre feed interface Distribution of publications totally or partially based on observations made at the M. G. Fracastoro station Solar facilities: The equatorial spar Solar facilities: Hα a image of the Sun Number of visitors from 1994 to

11 Foreword Premessa Lo scopo di questo rapporto è di presentare i risultati della attivitá dell Osservatorio astrofisico di Catania nel corso dell anno solare 2003 sul piano scientifico, tecnologico e di promozione culturale e scientifica nella scuola e nella società. Esso offre inoltre un utile strumento di documentazione rivolto alle istituzioni, locali e nazionali, che nell anno 2003 hanno in vario modo sostenuto le attività dell Osservatorio o hanno avuto rapporti con esso alle quali va il piú vivo ringraziamento per il supporto ricevuto. L Osservatorio Astrofisico di Catania (OACt) fa parte della rete di dodici Osservatori dell Istituto Nazionale di Astrofisica e dispone di due sedi. La principale è ubicata all interno della Cittadella Universitaria, e comprende gli uffici, la biblioteca, i Laboratori di ricerca, le officine ottico-meccaniche, e il telescopio per le osservazioni solari. La seconda sede, Mario Girolamo Fracastoro, è collocata in località Serra La Nave sul versante sud-est dell Etna a quota 1750 m s.l.m. nel comune di Ragalna (CT). Essa è la sede osservativa dotata di quattro telescopi ed una foresteria. L Osservatorio opera in stretta collaborazione con la sezione Astrofisica del Dipartimento di Fisica e Astronomia dell Università di Catania, che ha sede nel suo stesso edificio. Ivi si svolgono le attività di insegnamento, i corsi per il Dottorato di Ricerca, le attività connesse ai laboratori didattici, e le conferenze. Foreword The aim of this report is to present the main results achieved by Catania Astrophysical Observatory during 2003, in the fields of Astronomy and Astrophysics, technological development, and dissemination of the scientific culture in the schools and the society. It offers a detailed documentation on all the Observatory s activities and facilities and it is addressed, among others, to the Institutions who supported the Observatory during 2003, wich are deeply acknowledged. The Catania Astrophysical Observatory (OACt) is one of the twelve Observatories of the network of the Istituto Nazionale di Astrofisica and it has two separate seats. The main seat in Catania is inside the Catania University Campus, where research offices, library, laboratories, opto-mechanic workshops, and the solar observing station are located. The second one, dedicated to Mario Girolamo Fracastoro, is a mountain observing station on the south-west side of Mt. Etna at 1750 m a.s.l. (Ragalna, CT), where four telescopes and a guesthouse are located. The Catania Astrophysical Observatory strictly co-operates with the Astrophysical xi

12 xii FOREWORD Section of the Physics and Astronomy Department of the Catania University, hosted in the same building of the Observatory. There university and Ph.D. courses are usually held together with the training laboratory activities for the students and public conferences. Prof. Santo Catalano (Director)

13 Osservatorio Astrofisico di Catania: Staff directory 2003 Director Catalano Santo Board Belvedere G., Cutispoto G., Del Popolo S., Frasca A., Miraglia M., Pagano I., Strazzulla G., Rapisarda M.L., Scuderi S. Catania Astrophysical Observatory, /phone directory Name Position phon ANTONUCCIO Vincenzo Research Astronomer van 318 BARATTA Giuseppe Associate Astronomer gbaratta 313, 265 BECCIANI Ugo Research Astronomer ube 317, 218 BELLASSAI Giancarlo Technical Support gbellassai 303 BELLUSO Massimiliano Technical Support mbelluso 279 BONANNO Alfio Research Astronomer abo 319 BONANNO Giovanni Full Astronomer gbonanno 204, 254 BRUNO Pietro Technical Support pbruno 278 BUSÀ Enza Research Astronomer ebu 261 BUSNÈ Giuseppe Administration gbu 256 CALÌ Antonio Technical Support acali 205, 203 CALÌ Maddalena General Services 250 CARBONARO Giuseppe Technical Support gcarbonaro 252, 203 CARIPOLI Giuseppe Library gcaripoli 214 CARUSO Maria Rita MGF* site Staff continued on next page xiii

14 xiv OSSERVATORIO ASTROFISICO DI CATANIA: STAFF DIRECTORY 2003 continued from previous page Name Position phon CASTORINA Giovanni General Services 9, 208 CATALANO Santo Full Astronomer scat 219 CATANZARO Giovanni Research Astronomer gca 223 CATINOTO Enrico Technical Support ecatinoto 253 CORSARO Gaetano MGF* site Staff scor COSENTINO Rosario Research Astronomer rco 260, 259 COSTA Alessandro Computer Center alex.costa 273 COSTA Pierfrancesco Technical Support pcosta 264 CUTISPOTO Giuseppe Associate Astronomer gcutispoto 312 DEL POPOLO Santa Administration sdelpopolo 226 segreteria 226 DI BENEDETTO Rosario Technical Support sdibenedetto 270 DI MAURO Maria Pia Research Astronomer mdm 207 DISTEFANO Antonio Technical Support adistefano 200 DOMINA Daniela Library ddomina 268 FRASCA Antonio Research Astronomer afrasca 240 GENTILE Giovanni Technical Support ggentile 201, 203 GIUFFRIDA Alfio Computer Center agiuffrida 217,218 GRECO Vincenzo Technical Support vgreco 200 LAMPÒ Rocco Technical Support rlampo 300, 301 LANZA Antonino F. Associate Astronomer nlanza 238 LANZAFAME Giuseppe Research Astronomer glanzafame 316 LEONE Franco Research Astronomer fleone 229 LETO Giuseppe Research Astronomer gle 311 LO PRESTI Carmelo Administration clopresti 215, 218 MAGAZZÙ Antonio Associate Astronomer antonio MANGANO Angela Library amangano 248 library 248 MARILLI Ettore Associate Astronomer emarilli 246 MARTINETTI Eugenio Technical Support emartin 304 MASSIMINO Piero Computer Center pmassimino 216, 218 MELLINI Maria Administration amministr 225 MESSINA Sergio Research Astronomer sme 230 MESSINEO Marina Administration mmes 226 MICCICHÈ Antonio Technical Support ami 209 MIRAGLIA Massimo Technical Support mmiraglia 271, 203 OCCHIPINTI Giovanni Technical Support goc 305, 203 PAGANO Isabella Research Astronomer ipagano 243 PALUMBO M. Elisabetta Research Astronomer mepalumbo 242, 265 PULEO Giuseppe Technical Support mpuleo 201, 203 RAPISARDA Maria Luisa Administration mlrapisarda 224 amministr 224 continued on next page

15 continued from previous page Name Position phon RECUPERO Daniela Library drecupero 247 ROMANIA Valentina Administration vromania 262 SACCONE Rosaria Administration 227 SANTAGATI Luigia Library gsantagati 269 SANTOCONO Orazio General Services 9, 208 SARDONE Stefano Technical Support ssardone 306, 203 SCAFILI Marcella Administration mscafili 263 SCIUTO Santo Technical Support ssciuto 233, 232 SCUDERI Cosimo MGF* site Staff SCUDERI Salvatore Research Astronomer sscuderi 255, 254 SPADARO Daniele Associate Astronomer dspadaro 234 SPINELLA Franco Technical Support fspinella 314, 265 STRAZZULLA Giovanni Full Astronomer gianni 315, 265 TERNULLO Maurizio Research Astronomer mternullo 231 TIMPANARO M.Cristina Technical Support mctimpanaro 259, 254 TRINGALE Gaetana Administration segreteria 228 VENTIMIGLIA Agata General Services 9, 208 VENTURA Rita Research Astronomer rventura 258 WANAUSEK Antonino Technical Support awanausek 302 ZINGALE Giuseppe General Services 277 xv Department of Physics and Astronomy-University of Catania Astrophysics section Head of Astrophysics Section BELVEDERE Gaetano BELVEDERE Gaetano Associate Professor gbelvedere 236 ANASTASI Clelia Administration canastasi 211 BLANCO Carlo Associate Professor cblanco 245 CATALANO Franco Associate Professor fcatalano 221 LANZAFAME Alessandro Researcher acl 239 PATERNÒ Lucio Full Professor lpaterno 235 RODONÒ Marcello Full Professor mrodono 220 SPAMPINATO Cinzia Administration 210 ZAPPALÀ Aldo Associate Professor razappala 241 ZUCCARELLO Francesca Associate Professor fzucca 237 Ph.D. Students and Fellows BIAZZO Katia Ph.D. Student kbi 328 CIGNA Massimo Fellow mci 244 continued on next page

16 xvi OSSERVATORIO ASTROFISICO DI CATANIA: STAFF DIRECTORY 2003 continued from previous page Name Position phon COMPARATO Marco Fellow mco CONTARINO Lidia Postdoc INAF lcont 331 DI GIORGIO Salvatore Ph. D. Student Di STEFANO Elisa Fellow eds FERRO Daniela Fellow dfe LECCIA Silvio Ph. D. Student PALAZZO Giusimelissa Ph. D. Student gpal ROMANO Paolo Postdoc University of Catania prom 329 ROMEO Alessio Ph. D. Student Table 1: Catania Astrophysical Observatory, /phone directory * MGF: Mario Girolamo Fracastoro

17 Chapter 1 OACt 2003 Summary/Highlight Introduzione al rapporto dell OACt per l anno 2003 Le attività dell anno 2003 sono state fortemente condizionate dai lavori di ristrutturazione e recupero dell edificio principale della sede di Catania effettuati a cura dell Università di Catania. Le operazioni di spostamento e la sistemazione temporanea in locali insufficienti, legati a tali lavori di ristrutturazione, hanno costretto i ricercatori ed il personale tutto a lavorare in condizioni di estremo disagio, per tutto l anno. Tuttavia le attività scientifiche sono proseguite con elevato standard ed il personale tutto ha svolto i propri compiti con impegno e serietà. L Osservatorio di Catania con la stazioni eliofisica e la sede dell Etna (Serra La Nave) rimane uno dei pochi osservatori in Italia in cui l attività osservativa locale prosegue ad alti livelli di continuità e di qualità con inserimento in programmi nazionali ed internazionali. All attività osservativa si affianca una intensa attività di ricerca nel campo della fisica stellare e solare di riconosciuta valenza nazionale ed internazionale. Presso l Osservatorio operano inoltre il laboratorio di astrofisica sperimentale, il laboratorio dei rivelatori per l astrofisica e il laboratorio di calcolo ad alte prestazioni. L attività di ricerca svolta nel 2003 si può suddividere a grandi linee in: Fisica solare. Le ricerche di fisica solare si sviluppano su linee di tipo osservativo, che utilizzano facilities internazionali da terra e dallo spazio, e di tipo teorico. Esse comprendono studi di fisica della corona solare, modelli idrodinamici e di riscaldamento del complesso cromosfera-tr-corona, modelli dinamo con circolazione meridiana, eliosismologia e struttura interna. Programmi osservativi sono condotti con i satelliti SOHO, TRACE e con il telescopio THEMIS. Un aspetto rilevante alle osservazioni sistematiche del Sole è dato dall inserimento nel Global Hα Network organizzato dal Big Bear Solar Observatory e nel programma di ricerca sullo Space Weather attraverso campagne di Flare Warning. Fisica stellare. Gli studi di fisica stellare presso l Osservatorio Astrofisico di Catania costituiscono il programma di ricerca più corposo ed articolato, con una parte prevalente dedicata all attività magnetica stellare in stelle singole e doppie, dalla fotosfera alla corona con osservazioni e modelli, oscillazioni stellari e problematiche di struttura stellare con attività teorica ed osservativa, composizione chimica e stelle chimicamente peculiari, problemi osservativi di formazione ed evoluzione stellare, processi nucleari di interesse astrofisico. 1

18 2 CHAPTER 1. OACT 2003 SUMMARY/HIGHLIGHT Ammassi di galassie cosmologia. Si tratta di un gruppo di piccole dimensioni che si occupa di modellizzazione del plasma intergalattico e dei processi di riscaldamento di Ammassi di Galassie mediante codici paralleli a N-corpi e codici euleriani a griglia adattiva, modelli di generazione e propagazione di raggi cosmici di energie estreme in strutture a Grande Scala dell Universo. Laboratorio di Astrofisica Sperimentale. Le ricerche si riferiscono alle interazioni tra radiazione e materia in ambienti di interesse astrofisico, con sperimentazione delle modificazioni chimico-fisiche di bersagli solidi (silicati, materiali carboniosi, gas congelati) bombardati con fasci ionici energetici (3-200 kev) o con fotoni ultravioletti (Lyman-alpha nm, ovvero 10.2 ev). L impiantazione di ioni reattivi (H, C, N, O, Na) su silicati e le nuove specie chimiche che si formano nel processo vengono studiate in situ, mediante spettroscopia a riflessione e spettroscopia Raman. Laboratorio rivelatori per l Astronomia. L attività dal gruppo di ricerca sui rivelatori si articola in due aspetti principali: sviluppo di elettronica e software di controllo di rivelatori CCD, sviluppo e caratterizzazione di rivelatori di nuova generazione. In questo ultimo contesto sono da evidenziare lo sviluppo di rivelatore a conteggio di fotoni basato su Intensified CMOS-APS (IAPS), sviluppo di un sensore a matrice di Single photon avalanche diodes (SPAD) in collaborazione con ST Microelectronics, di Catania, caratterizzazione di un rivelatore a diamante sintetico in collaborazione con il Dipartimento di Astronomia e Scienza dello Spazio dell Università di Firenze ed altri istituti italiani. Il gruppo è fortemente impegnato nell upgrade dei sistemi di acquisizione di immagini nell ottico del TNG, e dei telescopi dell OAC. Calcolo ad alte prestazioni e visualizzazione scientifica (HPC). Il sistema di calcolo parallelo, realizzato tramite il progetto Alta formazione nel campo del calcolo ad alte prestazioni e problematiche astrofisiche attuali del MURST su finanziamenti dell Unione Europea, ha ricevuto nel 2002 un ulteriore finanziamento che ha consentito nel 2003 l upgrading del sistema IBM SP3 con un sistema SP4 a 8 processori paralleli, per un totale di 32 processori. Oltre allo sviluppo di codici paralleli nel campo della simulazione dell evoluzione delle galassie il programma prevede lo sviluppo di pacchetti di visualizzazione ed analisi specificamente orientati a dati di simulazioni e di archivio (AstroMD), calcolo e simulazioni su griglia computazionale (GRID) con gestione remota di simulazioni (AstroComp), orientati verso il Virtual Observatory L attività dell Osservatorio nel campo dell alta formazione anche nel 2003 ha trovato un notevole impegno, anche con la partecipazione come Socio Ordinario al Consorzio dell Istituto Superiore di Catania per la Formazione di Eccellenza, con la collaborazione con il Dipartimento di Fisica ed Astronomia nella didattica universitaria (parte di corsi, supporto ai corsi di laboratorio, esperienze di osservazioni astronomiche) e di dottorato. Astronomi dell Osservatorio sono relatori di tesi di Laurea e tutor di tesi di Dottorato. Purtroppo la mancanza di fondi non ha permesso il rinnovo della convenzione con l Università di Catania per una borsa di studio per il Dottorato di Ricerca. Questo documento descrive le attività di ricerca e lo sviluppo dell Osservatorio Astrofisico di Catania svolte nel Considerata la stretta collaborazione con la Sezione Astrofisica del Dipartimento di Fisica ed Astronomia in questo documento vengono descritte anche le attività di tale gruppo in una presentazione unitaria come risultato delle sinergie proficue della integrazione delle due istituzioni nella stessa struttura.

19 3 OACt 2003 report summary/highlight All activities in 2003 have been strongly hampered by renewal construction of the main building of the Cittá Universitaria. The works have been funded and handled by the Catania University. The empting operation of the building and temporary settling on inadequate crowded offices have compelled researchers and all personnel to work in a very comfortless condition, during all the year. However, research activities have been continued at high scientific level and all the personnel has afforded its job with high efficiency and awareness of duty. The Catania Observatory with the eliophysics station and the mountain station on Etna (Serra La Nave) remain one of the few italian astronomical institutions where observation activities are pursued with continuity and at high quality level, within national and international collaborations. The observation activities are complemented by theoretical and data analysis researches in the fields on solar and stellar physics well recognized in the national and international context. The Catania Observatory include also well equipped laboratories e.g. the Laboratory for Experimental Astrophysics, the Laboratory of Detectors for Astronomy and the High Performance Computing Laboratory. Research activity pursued in 2003 can be grouped within the following main fields: Solar Physics. Research on solar physics includes observation based activities, which use international ground and space facilities, and theoretical researches. All these researches relate to physical studies of the solar corona, hydrodynamic models, heating mechanisms of the chromosphere-transition Region complex, dynamo models which include meridian circulation, elioseismology and internal structure of the Sun. A relevant aspect of the systematic solar monitoring is the participation into the Global Hα Network coordinated by the Big Bear Solar Observatory and into the Space Weather program through Flare Warning campaigns. Stellar Physics. Studies on stellar physics constitute the main body of research at Catania Astrophysical Observatory. The more relevant part relates to the magnetic activity studies on single and binary stars, from the photosphere to the corona from observational and theoretical point of view. Stellar oscillations and internal structure of stars, chemical composition, chemically peculiar stars, as well as observational aspects of formation and evolution of stars. Problems of nuclear processes of astrophysical interest are also investigated. Clusters of galaxies and cosmology. This relatively small group recently formed is working in modelling the intergalactic plasma and on the heating processes of clusters of galaxies by means of N-body parallel, numerical codes and eulerian codes with adaptive grids, as well as on models for the generation and propagation of extremely energetic cosmic rays in large structures of the universe. Laboratory for Experimental Astrophysics. Researches in this lab refer to the experiments on the interaction of radiation with iced material in environment of astrophysical interest. Chemical and physical modifications induced on solid targets (silicate, carbon materials, and iced gas) by bombardment with energetic ion beams (3-200 kev) or UV photons (Lyman-α 121,6 nm = 10,2 ev). Implantation of reactve ions (H, C, N, O, Na) on silicates, and the new formed species are studied in situ through diffuse reflection, and Raman spectroscopy.

20 4 CHAPTER 1. OACT 2003 SUMMARY/HIGHLIGHT Laboratory of detectors for Astronomy. The activity of the research group is devoted to two main activities: development of control electronics and software for CCD detectors, implementation and characterization of new technology detectors. Within the latter activity it is worth to mention the preparation of photon counting imaging system based on Intensified CMOS-APS (IAPS), implementation of Single Photon Avalange Diodes (SPAD) matrix in collaboration with the Catania R&D section of the ST Microelectronics, and characterization of a detector based on synthetic diamond in collaboration with the Department of Astronomy and Science of Space of Florence University. Furthermore the group is deeply engaged in the improvement and upgrading of the image acquisition systems of the Galileo National Telescope (TNG) and of the Catania telescopes. High Performance Computation (HPC) and scientific visualization. The parallel computing system, implemented within the special project Alta formazione nel campo del calcolo ad alte prestazioni e problematiche astrofisiche attuali of the MURST on the base of EU funds, has received further support in 2002, which allowed in 2003 the upgrading of IBM SP3 with an additional IBM SP4 system thus having a system of 32 parallel processors. In addition to parallel numerical codes in the field of galaxies simulation models, the program is devoted to the development of visualization packages specially oriented to archive and simulation data (AstroMD), computation and simulation on computational grid (GRID) with remote management (AstroComp) orinted to the Virtual Observatory Also in 2003 the Observatory has payed special attention to the high level formation with the partnerhips in the Consorzio dell Istituto Superiore di Catania per la Formazione di Eccellenza. Collaboration with the Department of Physics and Astronomy of the Catania University for the academic activity, i.e. delivery of university and PhD courses, use of observatory labs and telescopes for the experimental and practical exercises. Astronomers of the observatory are currently tutors for the Degree or PhD thesis work. Unfortunately, due to the reduction of funds the special agreement with the Catania University for a PhD fellowship could not be renewed. The present document is aimed to the description of research activity and development of Catania Astrophysical Observatory achieved in Taking into account the tight collaboration with the Astrophysic Section of the Department of Physics and Astronomy of the Catania University, activities of both institutions are presented in this document to stress the positive effects of the unitary scientific policy. Prof. Santo Catalano (Director)

21 Chapter 2 Research 2.1 Solar Physics INAF Researchers: University Researchers: Postdocs: A. Bonanno, M. P. Di Mauro, A. F. Lanza, D. Spadaro, M. Ternullo, R. Ventura G. Belvedere, A. C. Lanzafame, L. Paternò R. A. Zappalà, F. Zuccarello L. Contarino, P. Romano Solar physics studies carried out in Catania cover nearly all the regions of the Sun, from its interior, to the surface and corona. These studies include the traditional systematic patrol of solar activity, the structure and the dynamics of the solar interior and surface, the theoretical investigation about the generation and evolution of magnetic fields. Researchers, since several years, are actively involved in some of the most important space missions devoted to the observations of the solar atmosphere, in particular the ESA/NASA Solar and Heliospheric Observatory (SOHO) and the NASA Transition Region and Coronal Explorer (TRACE). This has allowed the development of activities, among the others, concerning the spectroscopic diagnostics and modelling of coronal magnetic structures and of the solar wind source regions. More specifically, research activities have been conducted according to the following scheme Systematic patrol of photospheric and chromospheric activity The systematic observations of the Sun in white light and Hα line have been carried on in the framework of an international collaboration aimed at performing the patrol of solar activity. The data acquired within this project refer to: sunspots, faculae, quiescent and active prominences on the disk and on limb, flares. These data are daily sent to the various international collecting centers and put on the web page of the Observatory. A Flare Warning campaign recently started, within the international research programme on Space Weather. The campaign is based on the following operations: 5

22 6 CHAPTER 2. RESEARCH Figure 2.1: Distribution of data and international cooperations involving the solar observations carried out in Catania. observations of active regions appearing on the solar disc, both in the photosphere and chromosphere; comparison of the active regions configuration with that observed on the previous day; comparison with the magnetograms available on Big Bear Observatory web page; singling out active regions which, according to some standard parameters, have the highest probability to give rise to flares and/or filament eruptions; warning to the national and international scientific community, as well as to the teams of space experiments involved in the Space Weather research programme. The final aim is to recognize in advance and to observe by both ground-based and space telescopes solar events which are capable of producing troubles in satellite payloads, or even in Earth-based instruments. Moreover, Catania Observatory collaborates to the Global High Resolution Hα Network and supports the activities of the French-Italian solar telescope Themis Spectroscopic diagnostic and modelling of coronal structures D. Spadaro discussed the principal results obtained by the investigations concerning the physical structure and the dynamics of coronal magnetic loops, putting into particular evidence the interesting contribution given to these studies by the most recent space

23 2.1. SOLAR PHYSICS 7 missions [66]. This short review also indicated the principal constraints on the theoretical/numerical models of magnetic loops that arise from these new findings. D. Spadaro, A. F. Lanza and A. C. Lanzafame, in cooperation with colleagues of the Naval Research Laboratory of Washington, DC and of the NASA Goddard Space Flight Center of Greenbelt, MD, have investigated the hydrodynamic behavior of coronal loops undergoing transient heating. This study was stimulated by a wealth of observational evidence for flows and intensity variations in non-flaring coronal loops, that leads to the conclusion that coronal heating is intrinsically unsteady and concentrated near the chromosphere. They carried out 1-D numerical simulations, in which the timescale assumed for the heating variations (3000 s) is comparable to the coronal radiative cooling time and the assumed heating location and scale height (10 Mm) are consistent with the values derived from TRACE studies. The model loops represent typical active-region loops: 40 to 80 Mm in length, reaching peak temperatures up to 6 MK. Spadaro and co-workers used ARGOS, a state-of-the-art numerical code with adaptive mesh refinement, in order to resolve adequately the dynamic chromospheric-coronal transition region sections of the loop. The new major results from this work are the following. (1) During much of the cooling phase, the loops exhibit densities significantly larger than those predicted by the well-known loop scaling laws, thus potentially explaining recent TRACE observations of overdense loops. (2) Throughout the transient heating interval, downflows appear in the lower transition region (T 0.1 MK) whose key signature would be persistent, redshifted UV and EUV line emission, as have long been observed. (3) Strongly unequal heating in the two legs of the loop drives siphon flows from the more strongly heated footpoint to the other end, thus explaining the substantial bulk flows in loops recently observed by CDS and SUMER. The results of these studies have implications for the understanding of the physical origins of coronal heating and related dynamic phenomena [120], [43]. D. Spadaro and R. Ventura investigated the properties of the interface between streamers and coronal holes at low heliocentric distances, observing the extended solar corona in the North-West quadrant by UVCS/SOHO. They measured the line profiles of the Hi Lyα and Ovi resonance doublet and the visible linearly polarized radiance at heliocentric distances ranging from 1.4 to 2.5 R, and colatitudes spanning from the North pole to the West equator with steps of 10 deg. The results show that both the line intensities and the line widths, in particular those of Ovi, exhibit sharp variations across the streamer boundaries, with a clear anticorrelation between intensities and widths (Fig. 2.2). These steep changes occur in a narrow transition region (5 deg 10 deg), right at the borders of the streamers, from 1.5 R onwards. The Ovi resonance doublet line ratio steeply increases at the edges of the streamer as well, but this occurs at higher heliocentric distances (above 2 R ). Hence the marked broadening of the Oiv lines and the considerable rise of their intensity ratio just outside of the borders are an evident signature of the transition from closed to open field lines in streamer magnetic field topologies. This behaviour also implies that a strong and preferential non-thermal heating of Oiv ions in the direction coinciding with the line of sight and the turn-on of a significant outflow occur in the open magnetic field region near or just outside of the streamer edges. Such conclusion may have important consequences for realistic theoretical models of streamers and the source regions of the slow solar wind. Paper submitted to A&A at the end of R. Ventura and D. Spadaro compared the physical properties of the extended solar corona inside streamers with those deduced for interstreamer regions, also considering the

24 8 CHAPTER 2. RESEARCH possible dependence of such differences on the phase of the solar activity cycle (study is in progress) Energetic events in the solar atmosphere: flares and eruptive prominences Solar flares are complex phenomena, characterized by a sudden and localized energy release ( erg), which produces emission of electromagnetic radiation, heat flow, bulk plasma motions, particle acceleration. Moreover, the observations have put in evidence that the primary energy release takes place in corona and subsequently involves the underlying layers of the solar atmosphere (Priest & Forbes, A&A Rev., 10, 313, 2002). Therefore the study of flares from the observational point of view must be carried on comparing data acquired in various spectral ranges, in order to have information on the physical processes occurring in different atmospheric layers. The results obtained from these studies seem to confirm the hypothesis that one of the physical processes at the base of flares is the magnetic reconnection, caused by breaking and successive merging of magnetic field lines. However, further observations are necessary to improve our knowledge about the role of some phenomena during these events (mechanisms of energy transport during the first phases of reconnection, chromospheric plasma evaporation in post-flare loops, role of shock waves in heating the plasma, etc.). It is also worth noting that more energetic flares (classes M and X), if associated with Coronal Mass Ejections (CME) directed towards the Earth, can have remarkable consequences on Space Weather and give rise to a series of phenomena that can interfere with some human activities (systems of radio communications, GPS positioning systems, electrical distribution networks, etc), so that, in a society more and more based on electronic systems, it becomes extremely important to be able to forecast such events in sufficient times in order to take the due precautions. In this framework, Contarino, Romano, Ternullo and Zuccarello, considered two main aspects of the subject of rapidly evolving events: the study of the characteristics that a group of spots must have in order to produce flares of classes X or M, and a more specific study on physical mechanisms at the base of solar flares. The first aspect has been treated by means of a statistical analysis, based both on data in the visible range, some acquired at Catania Astrophysical Observatory (OACT), others provided by NOAA, and on data in the X-ray range provided by GOES satellite, to determine what are the conditions which characterize active regions hosting M and X flares ([127]; [121]; Ternullo et al.,in progess). This analysis, together with an observational campaign carried out at OACT, allowed these researchers to set a Flare Warning system. For the second aspect, Zuccarello, Contarino and Romano, in cooperation with E. Priest (St. Andrews University, Scotland), have studied the flare activity occurred in active region NOAA 8421 using EUV (1600 and 171 Å) and WL images acquired by TRACE telescope, H α BBSO images, Mitaka magnetograms and YOHKOH hard X-ray data. The results obtained from this analysis confirmed that: i) flares triggered by a process of magnetic reconnection can be caused by the interaction between the magnetic field lines of a coronal arcade and a new magnetic flux tube emerging from the subphotospheric regions; ii) reconnection can occur in the loops of an arcade at gradually increasing heights as a filament rises towards the more external layers; iii) a process of chromospheric evaporation can be at the base of an increase of brightness in moss surrounding the footpoints of an

25 2.1. SOLAR PHYSICS 9 Figure 2.2: Image of the extended solar corona obtained by the LASCO C1 coronagraph on board SOHO on October 30, 1997, through a narrow-band Fabry-Pèrot filter at the centre of the ionfexiv 5303 Å line. Superposed on the LASCO image are the UVCS slit fields of view (white lines) at nominal slit height of 1.75 R, for P.A.=330 deg (a) and P.A.= 270 deg (b). The nominal heliocentric distance and P.A. for each slit refer to the distance and P.A. of the point along the slit that is closest to the limb (shown as a white dot). The Lyα and Oiv 1032 Å total line intensities and 1/e half-widths, as well as the Oiv line ratios, vs. position angle along slit (a) and (b) are shown at the bottom of the figure.

26 10 CHAPTER 2. RESEARCH arcade [128]. In another event two distinguished reconnection phenomena have been observed: the former in the low solar atmosphere, near a structure called cancelling magnetic feature (CMF) (see fig. 2.3), that caused the destabilization of a filament and the successive eruption of part of it, and the latter in corona, caused by the passage of the filament ([17],[87]). Such events provide the opportunity to verify the model of reconnection in the low solar atmosphere, proposed by Livitnenko (ApJ, 515, 435, 1999). As far as the prominence activation is concerned, many authors have put in evidence, both on theoretical and observational basis, the fundamental role carried out by the helicoidal configuration of the magnetic field in the prominence instability. In this context, Romano, Contarino and Zuccarello, have studied an event occurred in AR 9077 (see fig. 2.4), approximating the prominence to a curved cylindrical flux tube and measuring the Figure 2.3: Sequence of blue-shifted (left column), H α center (center column) and red shifted (right column) images acquired by THEMIS at (a) 17:13 UT, (b) 17:34 UT. The white arrow in the central image indicates the CMF. North is on the top, west on the right (f.o.v km 2 ). Figure 2.4: 171 Å image taken by TRACE at 23:29 UT during a prominence eruption. The bright helical structures in the prominence legs are clearly visible. North is on the left, west on the top.

27 2.1. SOLAR PHYSICS 11 helicoidal twist of the magnetic field lines using 171 Å images acquired by TRACE. They have estimated the critical twist value at which the eruption takes place and have observed a decrease of the total torsion of the field with time. Moreover, using magnetograms of AR 8375 acquired by MDI/SOHO, they have esti- Figure 2.5: Reconstruction of NOAA obtained from the images acquired by THEMIS telescope in the centre of the H α line on July 27, The field of view is km 2. North is on the top, west on the left. mated the magnetic helicity transport in corona, related to the emergence of new flux tubes and to their horizontal motion at photospheric level. Such analysis allowed them to confirm the important role played by helicity in prominence destabilization, and to characterize in the emergence of the already twisted magnetic field, the more efficient mechanism for the attainment of an unstable configuration ([41]; [42]; [116]) Emergence and evolution of solar active regions The detailed study of the configuration and distribution of emerging magnetic flux in the solar atmosphere during the formation of active regions plays an important role in order to obtain information on the origin and the emergence of magnetic flux tubes, with implications for the understanding of the phenomena at the base of the solar dynamo. In particular, the formation of active regions (AR) on the Sun is a consequence of the phenomena of magnetic buoyancy that take place in the layers below the photosphere and that subsequently involve the external layers of the solar atmosphere. Thanks to several observations, nowadays it is possible to give a detailed picture of the phenomena that are observed during the first evolutionary phases of an AR (see van Driel-Gesztelyi, L., IAU Colloquium 188, ESA SP-505, 113, 2002, for a review): plasma motions, formation of pores, appearance of loop structures, (called Arch Filament System or AFS), phenomena of coalescence of pores, etc. Despite that, it is not yet possible to establish, during the first evolutionary phases of an AR, if it will have a complete evolution (with an average