Author name code: berrilli ADS astronomy entries on 2022-09-14 author:"Berrilli, Francesco" ------------------------------------------------------------------------ Title: The Great Aurora of 4 February 1872 observed by Angelo Secchi in Rome Authors: Berrilli, Francesco; Giovannelli, Luca Bibcode: 2022JSWSC..12....3B Altcode: 2022arXiv220101171B Observation of auroras at low latitudes is an extremely rare event typically associated with major magnetic storms due to intense Earth-directed Coronal Mass Ejections. Since these energetic events represent one of the most important components of space weather, their study is of paramount importance to understand the Sun-Earth connection. Due to the rarity of these events, being able to access all available information for the few cases studied is equally important. Especially if we refer to historical periods in which current accurate observations from ground-based instruments or space were not available. Certainly, among these events, we must include the great aurora of February 4, 1872. An event whose effects have been observed in different regions of the Earth. What we could consider today a global event, especially for its effects on the communication systems of the time, such as the transatlantic cable that allowed a connection between the United States and Europe since 1866. In this paper, we describe the main results of the observations and studies carried out by Angelo Secchi at the Observatory of the Roman College and described in his Memoria sull'Aurora Elettrica del 4 Febbraio 1872 for the Notes of the Pontifical Academy of new Lincei. This note is extremely modern both in its multi-instrumental approach to the study of these phenomena and in its association between solar-terrestrial connection and technological infrastructures on the Earth. The Secchi's note definitely represents the first example of analysis and study of an event on a global scale, such as the Atlantic cable, affecting the Earth. What we nowadays call an extreme space weather event. Title: A Synergic Strategy to Characterize the Habitability Conditions of Exoplanets Hosted by Solar-Type Stars Authors: Reda, Raffaele; Di Mauro, Maria Pia; Giovannelli, Luca; Alberti, Tommaso; Berrilli, Francesco; Corsaro, Enrico Bibcode: 2022FrASS...9.9268R Altcode: We present a new synergic strategy that merges the potential of asteroseismology with solar space weather/climate techniques in order to characterize solar-like stars and their interaction with hosted exoplanets. The method is based on the use of seismic data obtained by the space missions Kepler/K2 and TESS Transiting Exoplanet Survey Satellite, coupled with stellar activity estimates deduced from ground-based campaigns (e.g., Mount Wilson Observatory HK Project). Our investigation allows us to determine not only highly accurate fundamental parameters of the mother star and its orbiting planet, but also to study the stellar magnetic activity and the star-planet interaction: in analogy to the Sun-Earth system, it is possible to infer the mean stellar wind acting on the exoplanet in order to define the conditions of the exoplanetary environment and the erosion of its atmosphere with an impact on the habitability of the planet. Title: The exoplanetary magnetosphere extension in Sun-like stars based on the solar wind - solar UV relation Authors: Reda, Raffaele; Giovannelli, Luca; Alberti, Tommaso; Berrilli, Francesco; Bertello, Luca; Del Moro, Dario; Di Mauro, Maria Pia; Giobbi, Piermarco; Penza, Valentina Bibcode: 2022arXiv220301554R Altcode: Earth's magnetosphere extension is controlled by solar activity level via solar wind properties. Understanding such a relation in the Solar System is useful to predict the condition of exoplanetary magnetosphere near Sun-like stars. We use measurements of a chromospheric proxy, the Ca II K index, and solar wind OMNI parameters to connect the solar activity variations on the decennial time scales to solar wind properties. The dataset span over the time interval 1965-2021, which almost entirely covers the last 5 solar cycles. Using both cross-correlation and mutual information analysis, a 3.2-year lag of the solar wind speed with respect to the Ca II K index is found. Analogously, a 3.6-year lag is found with respect to the dynamic pressure. A correlation between the solar wind dynamic pressure and the solar UV emission is therefore found and used to derive the Earth's magnetopause standoff distance. Moreover, the advantage of using a chromospheric proxy, such as the Ca II K index, opens the possibility to extend the relation found for the Sun to Sun-like stars, by linking stellar variability to stellar wind properties. The model is applied to a sample of Sun-like stars as a case study, where we assume the presence of an Earth-like exoplanet at 1 AU. Finally, we compare our results with previous estimates of the magnetosphere extension for the same set of sun-like stars. Title: Scaling properties of magnetic field fluctuations in the quiet Sun Authors: Giannattasio, F.; Consolini, G.; Berrilli, F.; De Michelis, P. Bibcode: 2022A&A...659A.180G Altcode: Context. The study of the dynamic properties of small-scale magnetic fields in the quiet photosphere is important for several reasons: (i) it allows us to characterise the dynamic regime of the magnetic field and points out some aspects that play a key role in turbulent convection processes; (ii) it provides details of the processes and the spatial and temporal scales in the solar photosphere at which the magnetic fields emerge, vary, and eventually decay; and (iii) it provides physical constraints on models, improving their ability to reliably represent the physical processes occurring in the quiet Sun.
Aims: We aim to characterise the dynamic properties of small-scale magnetic fields in the quiet Sun through the investigation of the scaling properties of magnetic field fluctuations.
Methods: To this end, we applied the structure functions analysis, which is typically used in the study of complex systems (e.g. in approaching turbulence). In particular, we evaluated the so-called Hölder-Hurst exponent, which points out the persistent nature of magnetic field fluctuations in the field of view targeted at a whole supergranule in the disc centre.
Results: We present the first map of a solar network quiet region as represented by the Hölder-Hurst exponent. The supergranular boundary is characterised by persistent magnetic field fluctuations, which indicate the occurrence of longer-memory processes. On the contrary, the regions inside the supergranule are characterised by antipersistent magnetic field fluctuations, which suggest the occurrence of physical processes with a short memory. Classical Kolmogorov homogeneous and isotropic turbulence, for instance, belongs to this class of processes. The obtained results are discussed in the context of the current literature. Title: HiRISE - High-Resolution Imaging and Spectroscopy Explorer - Ultrahigh resolution, interferometric and external occulting coronagraphic science Authors: Erdélyi, Robertus; Damé, Luc; Fludra, Andrzej; Mathioudakis, Mihalis; Amari, T.; Belucz, B.; Berrilli, F.; Bogachev, S.; Bolsée, D.; Bothmer, V.; Brun, S.; Dewitte, S.; de Wit, T. Dudok; Faurobert, M.; Gizon, L.; Gyenge, N.; Korsós, M. B.; Labrosse, N.; Matthews, S.; Meftah, M.; Morgan, H.; Pallé, P.; Rochus, P.; Rozanov, E.; Schmieder, B.; Tsinganos, K.; Verwichte, E.; Zharkov, S.; Zuccarello, F.; Wimmer-Schweingruber, R. Bibcode: 2022ExA...tmp...21E Altcode: Recent solar physics missions have shown the definite role of waves and magnetic fields deep in the inner corona, at the chromosphere-corona interface, where dramatic and physically dominant changes occur. HiRISE (High Resolution Imaging and Spectroscopy Explorer), the ambitious new generation ultra-high resolution, interferometric, and coronagraphic, solar physics mission, proposed in response to the ESA Voyage 2050 Call, would address these issues and provide the best-ever and most complete solar observatory, capable of ultra-high spatial, spectral, and temporal resolution observations of the solar atmosphere, from the photosphere to the corona, and of new insights of the solar interior from the core to the photosphere. HiRISE, at the L1 Lagrangian point, would provide meter class FUV imaging and spectro-imaging, EUV and XUV imaging and spectroscopy, magnetic fields measurements, and ambitious and comprehensive coronagraphy by a remote external occulter (two satellites formation flying 375 m apart, with a coronagraph on a chaser satellite). This major and state-of-the-art payload would allow us to characterize temperatures, densities, and velocities in the solar upper chromosphere, transition zone, and inner corona with, in particular, 2D very high resolution multi-spectral imaging-spectroscopy, and, direct coronal magnetic field measurement, thus providing a unique set of tools to understand the structure and onset of coronal heating. HiRISE's objectives are natural complements to the Parker Solar Probe and Solar Orbiter-type missions. We present the science case for HiRISE which will address: i) the fine structure of the chromosphere-corona interface by 2D spectroscopy in FUV at very high resolution; ii) coronal heating roots in the inner corona by ambitious externally-occulted coronagraphy; iii) resolved and global helioseismology thanks to continuity and stability of observing at the L1 Lagrange point; and iv) solar variability and space climate with, in addition, a global comprehensive view of UV variability. Title: A Prototype of a Large Tunable Fabry-Pérot Interferometer for Solar Spectroscopy Authors: Greco, V.; Sordini, A.; Cauzzi, G.; Cavallini, F.; Del Vecchio, C.; Giovannelli, L.; Berrilli, F.; Del Moro, D.; Reardon, K.; Pietraszewski, K. A. R. B. Bibcode: 2022PASP..134a5007G Altcode: 2021arXiv211202224G Large Fabry-Pérot Interferometers (FPIs) are used in a variety of astronomical instrumentation, including spectro-polarimeters for 4 m class solar telescopes. In this work we comprehensively characterize the cavity of a prototype 150 mm FPI, sporting a novel, fully symmetric design. Of particular interest, we define a new method to properly assess the gravity effects on the interferometer's cavity when the system is used in either the vertical or horizontal configuration, both typical of solar observations. We show that the symmetric design very effectively limits the combined effects of pre-load and gravity forces to only a few nm over a 120 mm diameter illuminated surface, with gravity contributing ~2 nm peak-to-valley (~0.3 nm rms) in either configuration. We confirm a variation of the tilt between the plates of the interferometer during the spectral scan, which can be mitigated with appropriate corrections to the spacing commands. Finally, we show that the dynamical response of the new system fully satisfies typical operational scenarios. We conclude that large, fully symmetric FPIs can be safely used within solar instrumentation in both, horizontal and vertical position, with the latter better suited to limiting the overall volume occupied by such an instrument. Title: Prediction of Sunspot and Plage Coverage for Solar Cycle 25 Authors: Penza, Valentina; Berrilli, Francesco; Bertello, Luca; Cantoresi, Matteo; Criscuoli, Serena Bibcode: 2021ApJ...922L..12P Altcode: 2021arXiv211102928P Solar variability occurs over a broad range of spatial and temporal scales, from the Sun's brightening over its lifetime to the fluctuations commonly associated with magnetic activity over minutes to years. The latter activity includes most prominently the 11 yr sunspot solar cycle and its modulations. Space weather events, in the form of solar flares, solar energetic particles, coronal mass ejections, and geomagnetic storms, have long been known to approximately follow the solar cycle occurring more frequently at solar maximum than solar minimum. These events can significantly impact our advanced technologies and critical infrastructures, making the prediction for the strength of future solar cycles particularly important. Several methods have been proposed to predict the strength of the next solar cycle, cycle 25, with results that are generally not always consistent. Most of these methods are based on the international sunspot number time series, or other indicators of solar activity. We present here a new approach that uses more than 100 yr of measured fractional areas of the visible solar disk covered by sunspots and plages and an empirical relationship for each of these two indices of solar activity in even-odd cycles. We anticipate that cycle 25 will peak in 2024 and will last for about 12 yr, slightly longer than cycle 24. We also found that, in terms of sunspot and plage areas coverage, the amplitude of cycle 25 will be substantially similar or slightly higher than cycle 24. Title: The star-planet interaction by combining asteroseismic and space weather techniques Authors: Reda, Raffaele; Giovannelli, Luca; Berrilli, Francesco; Di Mauro, Maria Pia Bibcode: 2021plat.confE..31R Altcode: The characterization of exoplanets conditions cannot be based solely on the knowlegde of the planetary main parameters, since the properties and the activity level of the host star, as well as the effects of extreme space weather phenomena, need also to be considered. Here we propose a synergic strategy based both on an asteroseismic approach and a space weather/space climate analysis. By studying the oscillation spectra it is possible to derive the host star fundamental parameters, including a precise determination of the age. Combining this informations with those coming from observations in the UV spectrum of the star (Ca II H & K lines), and by using relations which we have already calibrated on the Sun (Reda et al. 2021 submitted), we are able to estimate the mean stellar wind acting on the exoplanets, enabling to estimate the erosion of their atmospheres. The best targets for this approach consists of terrestrial planets orbiting around solar-like stars, which are exactly the primary target of the PLATO mission. Title: Flare-forecasting Algorithms Based on High-gradient Polarity Inversion Lines in Active Regions Authors: Cicogna, Domenico; Berrilli, Francesco; Calchetti, Daniele; Del Moro, Dario; Giovannelli, Luca; Benvenuto, Federico; Campi, Cristina; Guastavino, Sabrina; Piana, Michele Bibcode: 2021ApJ...915...38C Altcode: 2021arXiv210500897C Solar flares emanate from solar active regions hosting complex and strong bipolar magnetic fluxes. Estimating the probability of an active region to flare and defining reliable precursors of intense flares are extremely challenging tasks in the space weather field. In this work, we focus on two metrics as flare precursors, the unsigned flux R, tested on Michelson Doppler Imager/Solar and Heliospheric Observatory data, one of the most used parameters for flare-forecasting applications, and a novel topological parameter D, representing the complexity of a solar active region. In greater detail, we propose an algorithm for the computation of the R value, which exploits the higher spatial resolution of Helioseismic Magnetic Imager maps. This algorithm leads to a differently computed R value, whose functionality is tested on a set of solar cycle 24 flares. Furthermore, we introduce a topological parameter based on the automatic recognition of magnetic polarity inversion lines in identified active regions and are able to evaluate its magnetic topological complexity. We use both a heuristic approach and a supervised machine-learning method to validate the effectiveness of these two descriptors to predict the occurrence of X- or M-class flares in a given solar active region during the following 24 hr period. Our feature ranking analysis shows that both parameters play a significant role in prediction performances. Moreover, the analysis demonstrates that the new topological parameter D is the only one, among 173 overall predictors, that is always present for all test subsets and is systematically ranked within the top 10 positions in all tests concerning the computation of the weights with which each predictor impacts the flare forecasting. Title: Stellar Turbulent Convection: The Multiscale Nature of the Solar Magnetic Signature Authors: Scardigli, Stefano; Berrilli, Francesco; Del Moro, Dario; Giovannelli, Luca Bibcode: 2021Atmos..12..938S Altcode: No abstract at ADS Title: A novel approach to identify resonant MHD wave modes in solar pores and sunspot umbrae: B − ω analysis Authors: Stangalini, M.; Jess, D. B.; Verth, G.; Fedun, V.; Fleck, B.; Jafarzadeh, S.; Keys, P. H.; Murabito, M.; Calchetti, D.; Aldhafeeri, A. A.; Berrilli, F.; Del Moro, D.; Jefferies, S. M.; Terradas, J.; Soler, R. Bibcode: 2021A&A...649A.169S Altcode: 2021arXiv210311639S The umbral regions of sunspots and pores in the solar photosphere are generally dominated by 3 mHz oscillations, which are due to p-modes penetrating the magnetic region. In these locations, wave power is also significantly reduced with respect to the quiet Sun. However, here we study a pore where not only is the power of the oscillations in the umbra comparable to, or even larger than, that of the quiet Sun, but the main dominant frequency is not 3 mHz as expected, but instead 5 mHz. By combining Doppler velocities and spectropolarimetry and analysing the relationship between magnetic field strength and frequency, the resultant B − ω diagram reveals distinct ridges that are remarkably clear signatures of resonant magneto-hydrodynamic (MHD) oscillations confined within the pore umbra. We demonstrate that these modes, in addition to velocity oscillations, are also accompanied by magnetic oscillations, as predicted from MHD theory. The novel technique of B − ω analysis proposed in this article opens up an exciting new avenue for identifying MHD wave modes in the umbral regions of both pores and sunspots. Title: Long-term correlations in solar proxies and solar wind parameters Authors: Giovannelli, Luca; Reda, Raffaele; Alberti, Tommaso; Berrilli, Francesco; Cantoresi, Matteo; Del Moro, Dario; Giobbi, Piermarco; Penza, Valentina Bibcode: 2021EGUGA..23.7536G Altcode: The long-term behaviour of the Solar wind and its impact on the Earth are of paramount importance to understand the framework of the strong transient perturbations (CMEs, SIRs). Solar variability related to its magnetic activity can be quantified by using synthetic indices (e.g. sunspots number) or physical ones (e.g. chromospheric proxies). In order to connect the long-term solar activity variations to solar wind properties, we use Ca II K index and solar wind OMNI data in the time interval between 1965 and 2019, which almost entirely cover the last 5 solar cycles. A time lag in the correlation between the parameters is found. This time shift seems to show a temporal evolution over the different solar cycles. Title: Three-dimensional Climate Simulations for the Detectability of Proxima Centauri b Authors: Galuzzo, Daniele; Cagnazzo, Chiara; Berrilli, Francesco; Fierli, Federico; Giovannelli, Luca Bibcode: 2021ApJ...909..191G Altcode: 2021arXiv210203255G The discovery of a planet orbiting around Proxima Centauri, the closest star to the Sun, opens new avenues for the remote observations of the atmosphere and surface of an exoplanet, Proxima b. To date, three-dimensional (3D) general circulation models (GCMs) are the best available tools to investigate the properties of the exo-atmospheres, waiting for the next generation of space- and ground-based telescopes. In this work, we use the Planet Simulator (PlaSim), an intermediate-complexity, flexible and fast 3D GCM, suited to handle all the orbital and physical parameters of a planet and to study the dynamics of its atmosphere. Assuming an Earth-like atmosphere and a 1:1 spin/orbit configuration (tidal locking), our simulations of Proxima b are consistent with a dayside open ocean planet with a superrotating atmosphere. Moreover, because of the limited representation of the radiative transfer in PlaSim, we compute the spectrum of the exoplanet with an offline radiative transfer code with a spectral resolution of 1 nm. This spectrum is used to derive the thermal phase curves for different orbital inclination angles. In combination with instrumental detection sensitivities, the different thermal phase curves are used to evaluate observation conditions at ground level (e.g., ELT) or in space (e.g., James Webb Space Telescope (JWST)). We estimated the exposure time to detect the Proxima b (assuming an Earth-like atmosphere) thermal phase curve in the far-IR with JWST with signal-to-noise ratio ≃1. Under the hypothesis of total noise dominated by shot noise, neglecting other possible extra contribution producing a noise floor, the exposure time is equal to 5 hr for each orbital epoch. Title: Long-term correlations in solar proxies and solar wind parameters Authors: Reda, Raffaele; Alberti, Tommaso; Berrilli, Francesco; Giobbi, Piermarco; Giovannelli, Luca; Penza, Valentina Bibcode: 2021csss.confE.192R Altcode: Solar variability related to its magnetic activity can be quantified by using synthetic indices (e.g. sunspots number) or physical ones (e.g. chromospheric proxies). In order to connect the long-term solar activity variations to solar wind properties, we use Ca II K index and solar wind OMNI data in the time interval between 1965 and 2019, which almost entirely cover the last 5 solar cycles. A time lag in the correlation between the parameters is found. This time shift seems to show a temporal evolution over the different solar cycles. The advantage to use a chromospheric proxy opens the possibility to extend the relation found for the Sun to link stellar variability and stellar wind properties in Sun-like stars. Title: A new method for detecting solar atmospheric gravity waves Authors: Calchetti, Daniele; Jefferies, Stuart M.; Fleck, Bernhard; Berrilli, Francesco; Shcherbik, Dmitriy V. Bibcode: 2021RSPTA.37900178C Altcode: 2020arXiv200800210C Internal gravity waves have been observed in the Earth's atmosphere and oceans, on Mars and Jupiter, and in the Sun's atmosphere. Despite ample evidence for the existence of propagating gravity waves in the Sun's atmosphere, we still do not have a full understanding of their characteristics and overall role for the dynamics and energetics of the solar atmosphere. Here, we present a new approach to study the propagation of gravity waves in the solar atmosphere. It is based on calculating the three-dimensional cross-correlation function between the vertical velocities measured at different heights. We apply this new method to a time series of co-spatial and co-temporal Doppler images obtained by SOHO/MDI and Hinode/SOT as well as to simulations of upward propagating gravity wave-packets. We show some preliminary results and outline future developments.

This article is part of the Theo Murphy meeting issue `High-resolution wave dynamics in the lower solar atmosphere'. Title: Torsional oscillations within a magnetic pore in the solar photosphere Authors: Stangalini, Marco; Erdélyi, Robertus; Boocock, Callum; Tsiklauri, David; Nelson, Christopher J.; Del Moro, Dario; Berrilli, Francesco; Korsós, Marianna B. Bibcode: 2021NatAs...5..691S Altcode: 2021NatAs.tmp...82S Alfvén waves have proven to be important in a range of physical systems due to their ability to transport non-thermal energy over long distances in a magnetized plasma. This property is of specific interest in solar physics, where the extreme heating of the atmosphere of the Sun remains unexplained. In an inhomogeneous plasma such as a flux tube in the solar atmosphere, they manifest as incompressible torsional perturbations. However, despite evidence in the upper atmosphere, they have not been directly observed in the photosphere. Here, we report the detection of antiphase incompressible torsional oscillations observed in a magnetic pore in the photosphere by the Interferometric Bidimensional Spectropolarimeter. State-of-the-art numerical simulations suggest that a kink mode is a possible excitation mechanism of these waves. The excitation of torsional waves in photospheric magnetic structures can substantially contribute to the energy transport in the solar atmosphere and the acceleration of the solar wind, especially if such signatures will be ubiquitously detected in even smaller structures with the forthcoming next generation of solar telescopes. Title: Current state and perspectives of Space Weather science in Italy Authors: Plainaki, Christina; Antonucci, Marco; Bemporad, Alessandro; Berrilli, Francesco; Bertucci, Bruna; Castronuovo, Marco; De Michelis, Paola; Giardino, Marco; Iuppa, Roberto; Laurenza, Monica; Marcucci, Federica; Messerotti, Mauro; Narici, Livio; Negri, Barbara; Nozzoli, Francesco; Orsini, Stefano; Romano, Vincenzo; Cavallini, Enrico; Polenta, Gianluca; Ippolito, Alessandro Bibcode: 2020JSWSC..10....6P Altcode: Italian teams have been involved many times in Space Weather observational campaigns from space and from the ground, contributing in the advancing of our knowledge on the properties and evolution of the related phenomena. Numerous Space Weather forecasting and now-casting modeling efforts have resulted in a remarkable add-on to the overall progress in the field, at both national and international level. The Italian Space Agency has participated several times in space missions with science objectives related to Space Weather; indeed, an important field for the Italian scientific and industrial communities interested in Heliophysics and Space Weather, is the development of new instrumentation for future space missions. In this paper, we present a brief state-of-the-art in Space Weather science in Italy and we discuss some ideas on a long-term plan for the support of future scientific research in the related disciplines. In the context of the current roadmap, the Italian Space Agency aims to assess the possibility to develop a national scientific Space Weather data centre to encourage synergies between different science teams with interest in the field and to motivate innovation and new mission concept development. Alongside with the proposed recommendations, we also discuss how the Italian expertise could complement international efforts in a wider international Space Weather context. Title: The multiple jet impingement heat rejecter prototype for the GREGOR Solar Telescope Authors: Berrilli, Francesco; Manni, Fabio; Calchetti, Daniele; Caroli, Adalia; Del Moro, Dario; Giovannelli, Luca; Mainella, Giovanni; Viavattene, Giorgio; Florio, Arnaldo Bibcode: 2020SPIE11445E..4XB Altcode: Heat rejecter (HR) is a critical component of large aperture solar telescopes. It has the double task of acting as a Field Stop, to select the solar region to be studied, and as a heat rejecter to reduce the thermal load in the subsequent optics and keep the temperature of all internal surfaces within a few degrees of the ambient temperature. This last request is necessary to avoid the onset of internal convective air plumes and the subsequent generation of internal seeing. Since the thermal flux at the primary focus of a 4-m class telescope, as the European Solar Telescope (EST), is expected to be of the order of several MW=m2, even considering high HR reflectivity, the residual thermal load is conceivably high and a suitable Cooling Systems must be considered. Among the available cooling techniques, the most promising, and already applied in critical conditions such as for nuclear fusion reactor divertor, is the Multiple Jet Impingement (MJI) techniques. To fulfill the technological challenge of the HR for the next generation 4-m class European Solar Telescope (EST), a new prototype for the 1.5 meters GREGOR solar telescope has been developed as technological proof of concept. With the aim of testing this technique, a prototype of HR was realized to be mounted at the 1.5 meters GREGOR solar telescope at the at the Teide Observatory (Canary Islands, Spain). We present the HR thermal-hydraulic design based on the expected thermal load on the GREGOR primary focal plane (⋍ 1500W) and the constraints on the HR temperature. The MJI technology consists in a series of nozzles impinging the liquid coolant on the backside of the field stop hot wall. The high cooling capabilities of MJI relies on the high Reynolds numbers achievable, even with modest velocity flow. In this work we describe our efforts to design, fabricate and test the prototype of an HR to characterize the MJI technology. More in detail, we show the results of the hydraulic and thermal tests carried out in the opto-electronics laboratory of the Physics Department of the University of Rome Tor Vergata. Title: IBIS2.0: The new Interferometric BIdimensional Spectrometer Authors: Ermolli, Ilaria; Cirami, Roberto; Calderone, Giorgio; Del Moro, Dario; Romano, Paolo; Viavattene, Giorgio; Coretti, Igor; Giorgi, Fabrizio; Baldini, Veronica; Di Marcantonio, Paolo; Giovannelli, Luca; Guglielmino, Salvatore Luigi; Murabito, Mariarita; Pedichini, Fernando; Piazzesi, Roberto; Aliverti, Matteo; Redaelli, Edoardo Maria Alberto; Berrilli, Francesco; Zuccarello, Francesca Bibcode: 2020SPIE11447E..0ZE Altcode: We present the IBIS2.0 project, which aims to upgrade and to install the Interferometric BIdimensional Spectrometer at the solar Vacuum Tower Telescope (Tenerife, Spain) after its disassembling from the Dunn Solar Telescope (New Mexico, USA). The instrument is undergoing a hardware and software revision that will allow it to perform new spectropolarimetric measurements of the solar atmosphere at high spatial, spectral and temporal resolution in coordination with other ground- and space-based instruments. Here we present the new opto-mechanical layout and control system designed for the instrument, and describe future steps. Title: Tor Vergata Synoptic Solar Telescope: spectral characterization of potassium KI D1 MOFs Authors: Calchetti, Daniele; Viavattene, Giorgio; Terranegra, Luciano; Pietropaolo, Ermanno; Oliviero, Maurizio; Murphy, Neil; Jefferies, Stuart M.; Giovannelli, Luca; Del Moro, Dario; Berrilli, Francesco Bibcode: 2020SPIE11445E..2TC Altcode: Synoptic telescopes are fundamental tools in Solar Physics and Space Weather. Their typical high cadence full-disk observations are pivotal to assess the physical conditions on the Sun and to forecast the evolution in time of those conditions. The TSST (Tor vergata Synoptic Solar Telescope) is a synoptic telescope composed of two main full-disk instruments: an H-alpha Daystar SR-127 telescope and a Magneto Optical Filter (MOF)-based telescope in the Potassium KI at 769.90 nm. The MOF consists in a glass cell containing a Potassium vapor where a longitudinal magnetic field is applied. The MOF-based channel produces full disk Line-of-Sight magnetic field and velocity maps of the solar photosphere at 300 km above the solar surface. In this work, we present the optical setup, the spectral characterization of the MOF-based telescope, and details on the spectral characterization of the MOFs cells which is a required test to obtain calibrated magnetograms and dopplergrams. Title: Data reduction pipeline for MOF-based synoptic telescopes Authors: Forte, Roberta; Berrilli, Francesco; Calchetti, Daniele; Del Moro, Dario; Fleck, Bernhard; Giebink, Cynthia; Giebink, William; Giovannelli, Luca; Jefferies, Stuart Mark; Knox, Allister; Magrì, Maria; Murphy, Neil; Nitta, Garry; Oliviero, Maurizio; Pietropaolo, Ermanno; Rodgers, Wayne; Scardigli, Stefano; Viavattene, Giorgio Bibcode: 2020JSWSC..10...63F Altcode: There are strong scientific cases and practical reasons for building ground-based solar synoptic telescopes. Some issues, like the study of solar dynamics and the forecasting of solar flares, benefit from the 3D reconstruction of the Sun's atmosphere and magnetic field. Others, like the monitoring and prediction of space weather, require full disk observations, at the proper sampling rate, combining H-alpha images and Doppler velocity and magnetic field. The synoptic telescopes based on Magneto Optical Filters (MOF) using different lines are capable of measuring the line-of-sight Doppler velocity and magnetic field over the full solar disk at different ranges of height in the Sun's photosphere and low chromosphere. Instruments like the MOTH (Magneto-Optical filters at Two Heights), using a dual-channel based on MOFs operating at 589.0 nm (Na D2 line) and 769.9 nm (K D1 line), the VAMOS instrument (Velocity And Magnetic Observations of the Sun), operating at 769.9 nm (K D1 line), and the future TSST (Tor Vergata Synoptic Solar Telescope), using a dual-channel telescope operating at 656.28 nm (H-alpha line) and at 769.9 nm (K D1 line), allow to face both aspects, the scientific and the operative related to Space Weather applications. The MOTH, VAMOS and TSST data enable a wide variety of studies of the Sun, from seismic probing of the solar interior (sound speed, rotation, details of the tachocline, sub-surface structure of active regions), to the dynamics and magnetic evolution of the lower part of the solar atmosphere (heating of the solar atmosphere, identification of the signatures of solar eruptive events, atmospheric gravity waves, etc.), to the 3D reconstruction of the solar atmosphere and flare locations. However, the use of MOF filters requires special care in calibrating the data for scientific or operational use. This work presents a systematic pipeline that derives from the decennial use of MOF's technology. More in detail, the pipeline is based on data reduction procedures tested and validated on MOTH data acquired at Mees Solar Observatory of the University of Hawaii Haleakala Observatories and at South Pole Solar Observatory (SPSO), at the Amundsen-Scott South Pole Station in Antarctica, during Antarctica Summer Campaign 2016/17. Title: Magnetic Energy Balance in the Quiet Sun on Supergranular Spatial and Temporal Scales Authors: Giannattasio, Fabio; Consolini, Giuseppe; Berrilli, Francesco; Del Moro, Dario Bibcode: 2020ApJ...904....7G Altcode: Small-scale magnetic fields are ubiquitous in the quiet solar photosphere and may store and transfer huge amounts of energy to the upper atmospheric layers. For this reason, it is fundamental to constrain the energetics of the quiet Sun. By taking advantage of a 24 hr long magnetogram time series acquired by the Hinode mission without interruption, we computed, for the first time, the average rate of change of magnetic energy density on supergranular spatial and temporal scales. We found that the regions where this quantity is positive correspond with the longest magnetic field decorrelation times, with the latter being consistent with the timescales of magnetic energy density variation. This suggests that, on average, the energy provided by photospheric electric and magnetic fields and current density is effective in sustaining the magnetic fields in the network. Title: The Tor Vergata Synoptic Solar Telescope (TSST): A robotic, compact facility for solar full disk imaging Authors: Giovannelli, Luca; Berrilli, Francesco; Calchetti, Daniele; Del Moro, Dario; Viavattene, Giorgio; Pietropaolo, Ermanno; Iarlori, Marco; Rizi, Vincenzo; Jefferies, Stuart Mark; Oliviero, Maurizio; Terranegra, Luciano; Murphy, Neil Bibcode: 2020JSWSC..10...58G Altcode: By the continuous multi-line observation of the solar atmosphere, it is possible to infer the magnetic and dynamical status of the Sun. This activity is essential to identify the possible precursors of space weather events, such as flare or coronal mass ejections. We describe the design and assembly of TSST (Tor Vergata Synoptic Solar Telescope), a robotic synoptic telescope currently composed of two main full-disk instruments, a Hα telescope and a Potassium (KI D1) magneto-optical filter (MOF)-based telescope operating at 769.9 nm. TSST is designed to be later upgraded with a second MOF channel. This paper describes the TSST concepts and presents the first light observation carried out in February 2020. We show that TSST is a low-cost robotic facility able to achieve the necessary data for the study of precursors of space weather events (using the magnetic and velocity maps by the MOF telescope) and fast flare detection (by the Hα telescope) to support Space Weather investigation and services. Title: A New Method for Detecting Solar Atmospheric Gravity Waves Authors: Calchetti, D.; Jefferies, S.; Fleck, B.; Berrilli, F. Bibcode: 2020SPD....5120403C Altcode: For the past fifty years, acoustic waves generated near the solar surface have provided a powerful tool for the seismic mapping of the Sun's internal structure and dynamics. This field of research, known as helioseismology, has provided numerous fundamental breakthroughs in our understanding of the Sun's interior. Interestingly, the convective sources that produce the acoustic waves also produce internal gravity waves that propagate throughout the Sun's atmosphere. In principle, these waves can unlock the secrets of the Sun's atmosphere in much the same way as helioseismology revolutionized our view of the Sun's interior. However, despite ample evidence for their existence, we still do not fully understand the characteristics and overall role of the internal gravity waves for the dynamics and energetics of the solar atmosphere. Here we present a new approach to study the propagation of gravity waves in the solar atmosphere which finally opens the door for seismic mapping of the Sun's atmosphere. We show some preliminary results based on the analysis of both simulations and real observations, and we outline future developments. Title: Optical design of the Tor vergata Synoptic Solar Telescope (TSST) Authors: Viavattene, G.; Calchetti, D.; Berrilli, F.; Del Moro, D.; Giovannelli, L.; Pietropaolo, E.; Oliviero, M.; Terranegra, L. Bibcode: 2020arXiv200604921V Altcode: Synoptic full-disk solar telescope are fundamental instruments for present and future Solar Physics and Space Weather. They are typically used to study and monitor the solar activity by using high temporal cadence observations at different wavelength. The TSST (Tor vergata Synoptic Solar Telescope) is a new synoptic telescope composed of two spectral channels: an H$\alpha$ (656.3 nm) telescope and a Magneto Optical Filter (MOF)-based telescope in the Potassium (KI D1) absorption spectral line at 769.9 nm. H$\alpha$ observations are fundamental for the identification of flaring regions. The MOF-based telescope will produce line of sight magnetograms and dopplergrams of the solar photosphere, which are respectively used to study the magnetic field's geometry in active regions and dynamics of the solar atmosphere. In this work, we present an overview on the TSST and the optical design and characteristics of the MOF-based telescope, whose optical scheme is a double-Keplerian 80mm refractor with an aberration-free imaging lens. Title: Lower-thermosphere response to solar activity: an empirical-mode-decomposition analysis of GOCE 2009-2012 data Authors: Bigazzi, Alberto; Cauli, Carlo; Berrilli, Francesco Bibcode: 2020AnGeo..38..789B Altcode: Forecasting the thermosphere (the atmosphere's uppermost layer, from about 90 to 800 km altitude) is crucial to space-related applications, from space mission design to re-entry operations, space surveillance and more. Thermospheric dynamics is directly linked to the solar dynamics through the solar UV (ultraviolet) input, which is highly variable, and through the solar wind and plasma fluxes impacting Earth's magnetosphere. The solar input is non-periodic and non-stationary, with long-term modulations from the solar rotation and the solar cycle and impulsive components, due to magnetic storms. Proxies of the solar input exist and may be used to forecast the thermosphere, such as the F10.7 radio flux and the Mg II EUV (extreme-ultraviolet) flux. They relate to physical processes of the solar atmosphere. Other indices, such as the Ap geomagnetic index, connect with Earth's geomagnetic environment.

We analyse the proxies' time series comparing them with in situ density data from the ESA (European Space Agency) GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) gravity mission, operational from March 2009 to November 2013, therefore covering the full rising phase of solar cycle 24, exposing the entire dynamic range of the solar input. We use empirical mode decomposition (EMD), an analysis technique appropriate to non-periodic, multi-scale signals. Data are taken at an altitude of 260 km, exceptionally low for a low-Earth-orbit (LEO) satellite, where density variations are the single most important perturbation to satellite dynamics.

We show that the synthesized signal from optimally selected combinations of proxy basis functions, notably Mg II for the solar flux and Ap for the plasma component, shows a very good agreement with thermospheric data obtained by GOCE, during periods of low and medium solar activity. In periods of maximum solar activity, density enhancements are also well represented. The Mg II index proves to be, in general, a better proxy than the F10.7 index for modelling the solar flux because of its specific response to the UV spectrum, whose variations have the largest impact over thermospheric density. Title: Tor vergata Synoptic Solar Telescope: preliminary optical design and spectral characterization Authors: Calchetti, D.; Viavattene, G.; Berrilli, F.; Del Moro, D.; Giovannelli, L.; Oliviero, M. Bibcode: 2020JPhCS1548a2005C Altcode: Synoptic telescopes are fundamental tools in solar physics. They are tipically used for high cadence full-disk observations of the Sun at different wavelengths, in order to study the solar activity across the solar cycle. The TSST (Tor vergata Synoptic Solar Telescope) is a new synoptic telescope composed of a Ha filter-based telescope centered at 656 nm and a custom Magneto Optical Filter (MOF)-based telescope centered in the potassium (KI D1) absorption line at 770 nm. Observations of the Ha line are important for the detection of flaring regions and to track the Sun during the acquisition. The aim of the telescope is to monitor the solar activity using the line of sight (LoS) magnetograms and dopplergrams of the solar photosphere produced by the MOF-based telescope. Magnetograms are essential for the study of the geometry of the magnetic field in active regions, while dopplergrams can be used to study the dynamics of the solar lower atmosphere. In this work, we focus our attention on the custom MOF-based telescope. Firstly, we present the optical design of the instrument. It is a refractor telescope with a 80 mm aperture and an effective focal length of ∼1m. We also present details on the preliminary spectral characterization of this instrument at different cell temperatures, which is a mandatory step to calibrate magnetograms and dopplergrams. The results obtained during this first test are in agreement with the peaks separation (∼200 mÅ) and FWHM (∼ 50 mÅ) that we expected. Title: Can we forecast the arrival of ICMEs for the whole Solar Systems? Authors: Del Moro, Dario; Napoletano, Gianluca; Berrilli, Francesco; Giovannelli, Luca; Pietropaolo, Ermanno; Foldes, Raffaello Bibcode: 2020EGUGA..2218327D Altcode: Solar wind transients, i.e. interplanetary coronal mass ejections (ICMEs) drive Space Weather throughout the heliosphere and the prediction of their impact on different solar system bodies is one of the primary goals of the Planetary Space Weather forecasting. We realized a procedure based on the Drag-Based Model (Vrsnak et al., 2013, Napoletano et al. 2018) which uses probability distributions for the input parameters, and allows the evaluation of the uncertainty on the forecast. This approach has been tested against a set of ICMEs whose transit times are known, obtaining extremely promising results.We apply this model to propagate a sample of ICMEs from their sources on the solar surface into the heliosphere. We made use of the seminal works by Prise et al. (2015), Winslow et al. (2015) and Witasse et al. (2017) who tracked the ICMEs through their journeys using data from several spacecraft.Considering the extremely short computation time needed by the model to propagate ICMEs, this approach is a promising candidate to forecast ICME arrival to planetary bodies and spacecraft in the whole heliosphere, with relevant application to space-mission short-term planning. Title: Characterisation of are Soft X-ray distribution with solar magnetic activity Authors: Foldes, R.; Berrilli, F. Bibcode: 2020JPhCS1548a2011F Altcode: We analyse the 0.1 — 0.8 nm solar soft X-ray flux catalogue from Geostationary Operational Environmental Satellites (GOES), managed by NASA/NOAA, between September 1978 and September 2017, in order to investigate the possible role of solar activity and solar cycle epoch on the distribution of soft X-ray peak fluxes. We concentrate our attention on the last three solar cycles because solar activity proxies seem to indicate a decrease in the magnetic activity of our star. We know that flare soft X-ray peak fluxes are characterised by a power-law distribution with an index α ≃ 2 that shows a minor dependence on solar cycle. More in detail, we study the dependence of the power-law parameters during each single solar cycle (cycles 21-24) and during different regimes of solar activity defined using three different proxies: i) Sunspot Number (SSN), ii) Mg II core-to-wing ratio (Mg II Index), and iii) solar radio flux at 10.7 cm or 2800 MHz (F10.7). The power-law estimation analysis is performed in maximum likelihood estimation (MLE) fitting method with goodness-of-fit based on Kolmogorv- Smirnov test. Preliminary results indicate that the power-law index shows a slight decrease as solar activity decreases. This except for the F10.7 proxy. More in-depth statistical analysis is necessary to confirm our findings. Title: On the Drag parameter of ICME propagation models Authors: Napoletano, Gianluca; Foldes, Raffaello; Del Moro, Dario; Berrilli, Francesco; Giovannelli, Luca; Pietropaolo, Ermanno Bibcode: 2020EGUGA..2221007N Altcode: ICME (Interplanetary Coronal Mass Ejection) are violent phenomena of solar activity that affect the whole heliosphere and the prediction of their impact on different solar system bodies is one of the primary goals of the planetary space weather forecasting. The travel time of an ICME from the Sun to the Earth can be computed through the Drag-Based Model (DBM), which is based on a simple equation of motion for the ICME defining its acceleration as a=-Γ(v-w)v-w, where a and v are the CME acceleration and speed, w is the ambient solar-wind speed and Γ is the so-called drag parameter (Vršnak et al., 2013).In this framework, Γ depends on the ICME mass and cross-section, on the solar-wind density and, to a lesser degree, on other parameters. The typical working hypothesis for DBM implies that both Γ and w are constant far from the Sun. To run the codes, forecasters use empiricalinput values for Γ and w, derived by pre-existent knowledge of solar-wind condition and by solving the "inverted problem" (where the ICME travel time is known and the unknowns are Γ and/or w). Inthe 'Ensemble' approaches (Dumbovich et al., 2018; Napoletano et al. 2018), the uncertainty about the actual values of such inputs are rendered by Probability Distribution Functions (PDFs), accounting for the values variability and our lack of knowledge. Among those PDFs, that of Γ is poorly defined due to the relatively scarce statistics of recorded values. Employing a list of past ICME events, for which initial conditions when leaving the Sun and arrival conditions at the Earth are known, we employ a statistical approach to the Drag-Based Model to determine a measure of Γ and w for each case. This allows to obtain distributions for the model parameters on experimental basis and, more importantly, to test whether different conditions of relative velocity to the solar wind influence the value of the drag efficiency, as it must be expected for solid objects moving into an external fluid. In addition, we perform numerical simulations of a solid ICME-shaped structure moving into the solar-wind modelled as an external fluid. Outcomes from these simulations are compared with our experimental results, and thus employed to interpret them on physical basis. Title: Proxima Centauri b: infrared detectability in presence of stellar activity Authors: Galuzzo, D.; Berrilli, F.; Giovannelli, L. Bibcode: 2020JPhCS1548a2012G Altcode: We propose a general method to detect and characterize tidally-locked exoplanets in 1:1 spin/orbit resonance using the information coming from different infrared bands, analyzing the variation in time of the color of exoplanetary systems. We focus on the effects induced on the detectability of the system by the starspots of the active host-stars. The analysis is conducted on the Proxima Centauri system as a case study, comparing the results from a more complex 3D General Circulation Model simulation with a simple toy model. Our toy model includes the black-body emission in the infrared of the host-star, day-side and night-side of the tidally locked planet, as well as the starspots. The results are consistent with the 3D General Circulation Model and suggests that it is possible to disentangle the stellar activity effects from the presence of the planet in the exoplanetary system using the infrared color-color diagram technique. Title: Long-term (1749-2015) Variations of Solar UV Spectral Indices Authors: Berrilli, Francesco; Criscuoli, Serena; Penza, Valentina; Lovric, Mija Bibcode: 2020SoPh..295...38B Altcode: Solar radiation variability spans a wide range in time, ranging from seconds to decadal and longer. The nearly 40 years of measurements of solar irradiance from space established that the total solar irradiance varies by ≈0.1 % in phase with the Sun's magnetic cycle. Specific intervals of the solar spectrum, e.g., ultraviolet (UV), vary by orders of magnitude more. These variations can affect the Earth's climate in a complex non-linear way. Specifically, some of the processes of interaction between solar UV radiation and the Earth's atmosphere involve threshold processes and do not require a detailed reconstruction of the solar spectrum. For this reason a spectral UV index based on the (FUV-MUV) color has been recently introduced. This color is calculated using SORCE SOLSTICE integrated fluxes in the FUV and MUV bands. We present in this work the reconstructions of the solar (FUV-MUV) color and Ca II K and Mg II indices, from 1749-2015, using a semi-empirical approach based on the reconstruction of the area coverage of different solar magnetic features, i.e., sunspot, faculae and network. We remark that our results are in noteworthy agreement with latest solar UV proxy reconstructions that exploit more sophisticated techniques requiring historical full-disk observations. This makes us confident that our technique can represent an alternative approach which can complement classical solar reconstruction efforts. Moreover, this technique, based on broad-band observations, can be utilized to estimate the activity on Sun-like stars, that cannot be resolved spatially, hosting extra-solar planetary systems. Title: Chromospheric Heating by Acoustic Waves Compared to Radiative Cooling. II. Revised Grid of Models Authors: Abbasvand, Vahid; Sobotka, Michal; Heinzel, Petr; Švanda, Michal; Jurčák, Jan; del Moro, Dario; Berrilli, Francesco Bibcode: 2020ApJ...890...22A Altcode: 2020arXiv200103413A Acoustic and magnetoacoustic waves are considered to be possible agents of chromospheric heating. We present a comparison of deposited acoustic energy flux with total integrated radiative losses in the middle chromosphere of the quiet Sun and a weak plage. The comparison is based on a consistent set of high-resolution observations acquired by the Interferometric Bidimensional Spectrometer instrument in the Ca II 854.2 nm line. The deposited acoustic-flux energy is derived from Doppler velocities observed in the line core and a set of 1737 non-local thermodynamic equilibrium 1D hydrostatic semi-empirical models, which also provide the radiative losses. The models are obtained by scaling the temperature and column mass of five initial models by Vernazza et al. (1981; VAL) B-F to get the best fit of synthetic to observed profiles. We find that the deposited acoustic-flux energy in the quiet-Sun chromosphere balances 30%-50% of the energy released by radiation. In the plage, it contributes by 50%-60% in locations with vertical magnetic field and 70%-90% in regions where the magnetic field is inclined more than 50° to the solar surface normal. Title: Measuring the Dispersion Relation of Acoustic-Gravity Waves in the Solar Atmosphere Authors: Fleck, Bernhard; Jefferies, Stuart M.; Murphy, Neil; Berrilli, Francesco Bibcode: 2020ASSP...57..141F Altcode: We use localized measurements of the dispersion relation for acoustic-gravity waves to generate the first maps of the spatial structure of the sound speed, acoustic cut-off frequency, and radiative damping time in the Sun's lower atmosphere. These maps offer a new diagnostic for the solar atmosphere. Title: The ionosphere prediction service prototype for GNSS users Authors: Vadakke Veettil, Sreeja; Cesaroni, Claudio; Aquino, Marcio; De Franceschi, Giorgiana; Berrilli, Francesco; Rodriguez, Filippo; Spogli, Luca; Del Moro, Dario; Cristaldi, Alice; Romano, Vincenzo; Ronchini, Roberto; Di Rollo, Stefano; Guyader, Eric; Aragon-Angel, Angela Bibcode: 2019JSWSC...9A..41V Altcode: The effect of the Earth's ionosphere represents the single largest contribution to the Global Navigation Satellite System (GNSS) error budget and abnormal ionospheric conditions can impose serious degradation on GNSS system functionality, including integrity, accuracy and availability. With the growing reliance on GNSS for many modern life applications, actionable ionospheric forecasts can contribute to the understanding and mitigation of the impact of the ionosphere on our technology based society. In this context, the Ionosphere Prediction Service (IPS) project was set up to design and develop a prototype platform to translate the forecast of the ionospheric effects into a service customized for specific GNSS user communities. To achieve this overarching aim, four different product groups dealing with solar activity, ionospheric activity, GNSS receiver performance and service performance have been developed and integrated into a service chain, which is made available through a web based platform. This paper provides an overview of the IPS project describing its overall architecture, products and web based platform. Title: Observed Local Dispersion Relations for Magnetoacoustic-gravity Waves in the Sun’s Atmosphere: Mapping the Acoustic Cutoff Frequency Authors: Jefferies, Stuart M.; Fleck, Bernhard; Murphy, Neil; Berrilli, Francesco Bibcode: 2019ApJ...884L...8J Altcode: 2019arXiv191003198J We present the observed local dispersion relations for magnetoacoustic-gravity waves in the Sun’s atmosphere for different levels of magnetic field strength. We model these data with a theoretical local dispersion relation to produce spatial maps of the acoustic cutoff frequency in the Sun’s photosphere. These maps have implications for the mechanical heating of the Sun’s upper atmosphere, by magnetoacoustic-gravity waves, at different phases of the solar magnetic activity cycle. Title: The Complex Nature of Magnetic Element Transport in the Quiet Sun: The Lévy-walk Character Authors: Giannattasio, F.; Consolini, G.; Berrilli, F.; Del Moro, D. Bibcode: 2019ApJ...878...33G Altcode: The study of the dynamic properties of small-scale magnetic fields in the solar photosphere (magnetic elements, MEs) provides a fundamental tool to investigate some still unknown aspects of turbulent convection, and gain information on the spatial and temporal scales of evolution of the magnetic field in the quiet Sun. We track the MEs in a set of magnetogram long-time series acquired by the Hinode mission, and take advantage of a method based on entropy (the diffusion entropy analysis, DEA) to detect their dynamic regime, under the assumption that MEs are passively transported by the photospheric plasma flow. DEA has been proven to perform better than other standard techniques, and for the first time it is successfully used to provide the scaling properties of the displacement of MEs in the quiet Sun. The main results of this work, which represents an extension of the analysis presented in previous literature, can be summarized as two points: (i) MEs in the quiet Sun undergo a common dynamic turbulent regime independent of the local environment; (ii) the displacement of MEs exhibits a complex transport dynamics that is consistent with a Lévy walk. Title: Historical reconstruction of UV spectral indices Authors: Criscuoli, Serena; Berrilli, Francesco; Lovric, Mia; Penza, Valentina Bibcode: 2019AAS...23430205C Altcode: Solar radiation is one of the major natural drivers of Earth climate changes observed from the Maunder minimum. UV radiation in particular plays a major role in the ozone production/destruction processes and is known to affect the circulation patterns. Here we present reconstructions of the FUV-MUV color index and CaII and MgII core-to-wing indeces from 1749-2015, performed with a semi-epirical approach. We also present a reconstruction of the TSI variability. Our results are compared with reconstructions obtained with models employed in climatological studies. Title: Long-term reconstruction of Solar UV indices Authors: Criscuoli, Serena; Berrilli, Francesco; Lovric, Mia; Penza, Valentina Bibcode: 2019shin.confE..80C Altcode: Solar radiation is one of the major natural drivers of Earth climate variations. UV radiation in particular plays a major role in the ozone production/destruction processes and is known to affect the Earth's global circulation patterns. We present reconstructions of the FUV-MUV color index and CaII and MgII core-to-wing indices from 1749 to 2015, performed with a 4-components semi-empirical approach . Our model makes use of the Sunspot Number to estimate the UV color index and facula, network and sunspot area. The reconstructed UV indices, as well as the estimated area of magnetic structures, well compare with modern observations and historical records. Title: Forecasting the arrival of ICMEs throughout the heliosphere Authors: Del Moro, Dario; Berrilli, Francesco; Cristaldi, Alice; Forte, Roberta; Giovannelli, Luca; Napoletano, Gianluca; Pietropaolo, Ermanno Bibcode: 2019EGUGA..2113712D Altcode: ICME (Interplanetary Coronal Mass Ejection) are violent phenomena of solar activity that affect the whole heliosphere and the prediction of their impact on different solar system bodies is one of the primary goals of the planetary space weather forecasting. We realized a procedure based on the Drag-Based Model (Vrsnak et al., 2013, Napoletano et al. 2018) which uses probability distributions, rather than exact values, as input parameters, and allows the evaluation of the uncertainty on the forecast. We tested this approach using a set of CMEs whose transit times are known, obtaining extremely promising results. We present some further results from the application of this model to propagate a sample of ICMEs from their sources on the solar surface into the heliosphere. We made use of recent works by Prise et al. (2015) and Witasse et al. (2017) who tracked the ICMEs through their journeys using data from several spacecraft, tracing the ICMEs trajectory farther than Earth. Considering the extremely short computation time needed by the model to propagate ICMEs, it is a promising candidate for Space Weather application and to forecast ICME arrival to planetary bodies in the whole heliosphere. Title: Impact of solar and geomagnetic activity on thermospheric density during ESA's mission GOCE Authors: Berrilli, Francesco; Bigazzi, Alberto; Cauli, Carlo; Del Moro, Dario; Giovannelli, Luca; Lovric, Mija Bibcode: 2019EGUGA..2117564B Altcode: The impact of solar activity on thermospheric density during ESA's gravity mission GOCE has been investigated using different solar and geomagnetic indices. The analysed period (17 March, 2009 - 11 November, 2013) corresponds to the rising phase of solar cycle 24. Thermospheric density at a mean altitude of 254 km, derived from the high-precision accelerometers on board the GOCE satellite, represents a unique low-altitude dataset. The temporal behavior of Ap geomagnetic index and solar activity indices, i.e., the F10.7 flux and the Mg II core-to-wing ratio, have been examined and their correlations with GOCE thermospheric density studied. Then, solar indices have been decomposed into a set of modes, i.e., the intrinsic mode functions (IMFs), through the Empirical Mode Decomposition (EMD), a technique best suited in analysing non-stationary and non-periodic time signals. After the decomposition, certain subsets of of IMFs from the solar and geomagnetic indices and thermospheric density have been reconstructed and compared with the original GOCE dataset. The results suggest the relevance of using the Mg II index and EMD IMFs in describing the solar-thermospheric connection and reconstruct thermosperic density. Title: Climate and radiative properties of a tidally-locked planet around Proxima Centauri Authors: Galuzzo, Daniele; Berrilli, Francesco; Cagnazzo, Chiara; Giovannelli, Luca Bibcode: 2019EGUGA..2117750G Altcode: Three dimensional General Circulation Models (GCMs) are at the moment, the best available tools for investigating and predict the properties of the exo-atmospheres of Earth-like planets orbiting nearby stars. As a case study, we investigate the climate of the tidally locked Earth-like planet orbiting around Proxima Centauri via the 3-D GCM PlaSim and the 1-D radiative transfer model uvspec. A planetary preindustrial atmosphere, circular orbit and null axial tilt are assumed. The model output include the atmospheric dynamics, surface temperature and the presence of liquid water, as well as reflective and emission spectra of the planet at high resolution. Our tool can effectively retrieve atmospheric fingerprints of Earth-like planets of nearby systems, giving clues on the habitability of such planets, and has been used to set observational limits with space-born (e.g., JWST) and ground-based telescopes. Title: Calibration of statistical solar flare forecast parameters for images from SDO/HMI space instrument Authors: Giovannelli, Luca; Berrilli, Francesco; Cicogna, Domenico; Del Moro, Dario Bibcode: 2019EGUGA..2117832G Altcode: Forecasting the probability of a solar active region to flare is a challenging and pursued topic in the Space Weather field. The R value, developed by Schrijver (2007) is one of the most used descriptors of the photospheric magnetic field in active regions for flare forecasting applications. The R value method was calibrated on the magnetograms obtained from the Michelson Doppler Imager (MDI) instrument on board the Solar and Heliospheric Observatory (SOHO) between 1998 and 2006, during solar cycle 23. Since 2010, the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) satellite, is operative, collecting solar magnetograms with a spatial resolution 4 times higher than MDI, while the observation program of MDI was terminated on April 2011. We readjust the original R value algorithm to adapt it to the higher spatial resolution of HMI and we compare the statistical analysis of a sample of cycle 24th solar flares with the statistical analysis performed by Schrijver (2007). Furthermore, we propose a new parameter D, aimed to identify and count the number of magnetic polarity-inversion lines within the same active region, to better characterize magnetic active region morphology. The result of our statistical analysis show that both parameters are good descriptors of the behaviour of an AR and useful tools for flare forecasting, individually but especially if used together. Title: The Ionosphere Prediction Service Authors: Rodriguez, F.; Ronchini, L. R.; Di Rollo, S.; De Franceschi, G.; Cesaroni, C.; Spogli, L.; Romano, V.; Aquino, M.; Veettil, S.; Berrilli, F.; Del Moro, D.; Hutchinson, M.; Kalden, O.; Aragon-Angel, A.; Guyader, E. Bibcode: 2019NCimC..42...45R Altcode: The Ionosphere Prediction Service (IPS), project funded by European Commission within Horizon 2020 and currently ongoing, provides a prototype for a monitoring and prediction service of potential ionosphere-related disturbances affecting GNSS (Global Navigation Satellite System) user communities, to help these communities cope with the effects of the ionosphere and mitigate the related effects for the specific GNSS-based application/services. The aim of the IPS project is to design and develop a prototype platform able to translate the prediction and forecast of the ionosphere effects into a service customized for specific GNSS user communities. The objective is to alert the GNSS users in due time of an upcoming ionospheric event potentially harmful for GNSS and for the related operations in the given application field. The project team is composed of Telespazio (coordinator), Nottingham Scientific Ltd, Telespazio Vega DE, The University of Nottingham, The University of Rome Tor Vergata and the National Institute of Geophysics and Volcanology. The Joint Research Centre of the European Commission is also involved in the project. Title: The Probabilistic Drag Based Model for ICME propagation Authors: Berrilli, F.; Cristaldi, A.; Del Moro, D.; Forte, R.; Giovannelli, L.; Napoletano, G.; Pietropaolo, E. Bibcode: 2019NCimC..42...39B Altcode: ICME (Interplanetary Coronal Mass Ejection) are violent phenomena of solar activity that affect the whole heliosphere and the prediction of their impact on different solar system bodies is one of the primary goals of the planetary space weather forecasting. We present some results from the application of the P-DBM (Probabilistic Drag Based Model) to propagate a sample of ICMEs from their sources on the solar surface into the heliosphere. We made use of recent works who tracked the ICMEs through their journeys using data from several spacecraft, tracing the ICMEs trajectory further than Earth. Considering the extremely short computation time needed by the P-DBM to propagate ICMEs into the whole heliosphere, and its accuracy in reproducing the observations, we remark that it is a promising candidate for ICME Time of Arrival computation for Space Weather applications and for the need of present and future interplanetary missions, since it could be used as quick tool to forecast the arrival of ICME to planetary bodies in our Solar System other than the Earth. Title: Diffusion of emerging bipolar magnetic pairs in solar photosphere Authors: Giovannelli, L.; Giannattasio, F.; Del Moro, D.; Caroli, , A.; Berrilli, F. Bibcode: 2019NCimC..42....3G Altcode: Magnetic element tracking has been widely used to study the transport and diffusion of the magnetic field on the solar photosphere. From the analysis of the displacement spectrum of these tracers, it has been recently agreed that a regime of super-diffusion dominates the solar surface. We present in this work the analysis of the diffusion of emerging new bipolar magnetic elements for different initial separation of the footpoints. The displacement spectrum for bipolar couples interestingly shows a similar behaviour with respect to the case where all magnetic pairs are considered. To understand how such peculiar diffusion in the solar atmosphere takes places, we compare the displacement spectrum exploring the initial maximum separation parameter. Title: Statistical behaviour of a proxy of the entropy production rate of the solar photosphere Authors: Viavattene, G.; Berrilli, F.; Consolini, G.; Del Moro, D.; Giannattasio, F.; Giovannelli, L.; Penza, V. Bibcode: 2019NCimC..42....8V Altcode: The solar photosphere provides an incomparable laboratory to study turbulent convection in a dissipative non-equilibrium system. The evaluation of the entropy production rate on the solar photosphere and its probability distribution are the key issues for studying the non-equilibrium dynamics of the solar convection. The local entropy production rate is not offhandedly measurable on the solar photosphere, but it can be easily evaluated using the vertical heat flux as a proxy, which is given by the product between the line-of-sight velocity and the surface temperature. In this work, we present some preliminary results on statistics of the local entropy production rate via the vertical heat flux, using line-of-sight velocity and temperature maps of the solar photosphere which are derived from high-resolution spectro-polarimetric data making use of the Center of Gravity Method and the Stefan-Boltzmann law. Title: Introducing SWERTO: A regional space weather service Authors: Berrilli, F.; Casolino, M.; Cristaldi, A.; Del Moro, D.; Forte, R.; Giovannelli, L.; Martucci, M.; Mergé, M.; Napoletano, G.; Narici, L.; Pietropaolo, E.; Pucacco, G.; Rizzo, A.; Scardigli, S.; Sparvoli, R. Bibcode: 2019NCimC..42...47B Altcode: The Space WEeatherR TOr vergata university (SWERTO) service is an operational Space Weather service based on data from space-based and ground-based instruments, located in the Physics Department of the University of Rome Tor Vergata, Italy (UNITOV). The service is designed to promote the access to technical and scientific information by the regional industries whose technologies are sensible to Space Weather effects and allows registered users to access scientific data from instrumentation available to UNITOV researchers through national and international collaborations. To non-registered users, it provides a quick-look interface (spaceweather.roma2.infn.it) for the selection and visualization of such data and the visualization of the forecast for flare probability and Solar Energetic Particles (SEP) fluxes from prototype codes. The SWERTO database contains data on particles fluxes from the space missions ALTEA and PAMELA, and high-resolution and full disk spectro-polarimetric solar data. The solar data are related to solar Active Regions (ARs), observed at high resolution with the IBIS (Interferometric BIdimensional Spectropolarimeter) instrument, and full disk Line-of-Sight Doppler and magnetic field at different heights in the solar atmosphere, observed with the MOTH II telescope. SWERTO main goals are: i) design and realize a data-base with the particle fluxes recorded by the space missions and with the spectropolarimetric measurement of the solar photosphere; ii) allow an Open Access to the data-base and to prototype forecast to regional industries involved and exposed to Space Weather effects; iii) implement a tutorial and a FAQ section to help decision makers to realize and evaluate the risks from Space Weather events; iv) outreach and customer products. Title: Propagating Spectropolarimetric Disturbances in a Large Sunspot Authors: Stangalini, M.; Jafarzadeh, S.; Ermolli, I.; Erdélyi, R.; Jess, D. B.; Keys, P. H.; Giorgi, F.; Murabito, M.; Berrilli, F.; Del Moro, D. Bibcode: 2018ApJ...869..110S Altcode: 2018arXiv181012595S We present results derived from the analysis of spectropolarimetric measurements of active region AR12546, which represents one of the largest sunspots to have emerged onto the solar surface over the last 20 years. The region was observed with full-Stokes scans of the Fe I 617.3 nm and Ca II 854.2 nm lines with the Interferometric BIdimensional Spectrometer instrument at the Dunn Solar Telescope over an uncommon, extremely long time interval exceeding three hours. Clear circular polarization (CP) oscillations localized at the umbra-penumbra boundary of the observed region were detected. Furthermore, the multi-height data allowed us to detect the downward propagation of both CP and intensity disturbances at 2.5-3 mHz, which was identified by a phase delay between these two quantities. These results are interpreted as a propagating magnetohydrodynamic surface mode in the observed sunspot. Title: The Correlation of Synthetic UV Color versus Mg II Index along the Solar Cycle Authors: Criscuoli, Serena; Penza, Valentina; Lovric, Mija; Berrilli, Francesco Bibcode: 2018ApJ...865...22C Altcode: 2018arXiv180808439C UV solar irradiance strongly affects the chemical and physical properties of the Earth’s atmosphere. UV radiation is also a fundamental input for modeling the habitable zones of stars and the atmospheres of their exoplanets. Unfortunately, measurements of solar irradiance are affected by instrumental degradation and are not available before 1978. For other stars, the situation is worsened by interstellar medium absorption. Therefore, estimates of solar and stellar UV radiation and variability often rely on modeling. Recently, Lovric et al. used Solar Radiation and Climate Experiment (SORCE)/Stellar Irradiance Comparison Experiment (SOLSTICE) data to investigate the variability of a color index that is a descriptor of the UV radiation that modulates the photochemistry of planets’ atmospheres. After correcting the SOLSTICE data for residual instrumental effects, the authors found the color index to be strongly correlated with the Mg II index, a solar activity proxy. In this paper, we employ an irradiance reconstruction to synthetize the UV color and Mg II index with the purpose of investigating the physical mechanisms that produce the strong correlation between the color index and the solar activity. Our reconstruction, which extends back to 1989, reproduces very well the observations, and shows that the two indices can be described by the same linear relation for almost three cycles, thus ruling out an overcompensation of SORCE/SOLTICE data in the analysis of Lovric et al. We suggest that the strong correlation between the indices results from the UV radiation analyzed originating in the chromosphere, where atmosphere models of quiet and magnetic features present similar temperature and density gradients. Title: SWERTO: a Regional Space Weather Service Authors: Berrilli, Francesco; Casolino, Marco; Del Moro, Dario; Forte, Roberta; Giovannelli, Luca; Martucci, Matteo; Mergé, Matteo; Napoletano, Gianluca; Narici, Livio; Pietropalo, Ermanno; Pucacco, Giuseppe; Rizzo, Alessandro; Scardigli, Stefano; Sparvoli, Roberta Bibcode: 2018IAUS..335..348B Altcode: The Space WEeatherR TOr vergata university (SWERTO) service is an operational Space Weather service based on multi-instrument data from space-based (PAMELA, ALTEA) and ground-based (IBIS, MOTHII) instruments. The service (spaceweather.roma2.infn.it) is located at the Physics Department of the University of Rome Tor Vergata, Italy (UTOV) and will allow registered users to access scientific data from instrumentation available to UTOV researchers through national and international collaborations. It will provide intuitive software for the selection and visualization of such data and results from prototype forecasting codes for flare probability and Solar Energetic Particle (SEP) fluxes. The service is designed to promote access to technical and scientific information by the regional industries which employ technologies vulnerable to Space Weather effects. Basically, SWERTO aims to: i) design and construct a data-base with particle fluxes recorded by space missions and spectro-polarimetric measurements of the solar photosphere; ii) allow an Open Access to the data-base and to prototype forecasts to regional industries involved and exposed to Space Weather effects; iii) implement a tutorial and a FAQ section to help decision makers to became aware of and evaluate the risks from Space Weather events; iv) outreach and customer products. SWERTO has been financed by the Regione Lazio FILAS-RU-2014-1028 grant. Title: The MOTH II Doppler-Magnetographs and Data Calibration Pipeline Authors: Forte, Roberta; Jefferies, Stuart M.; Berrilli, Francesco; Del Moro, Dario; Fleck, Bernhard; Giovannelli, Luca; Murphy, Neil; Pietropaolo, Ermanno; Rodgers, Wayne Bibcode: 2018IAUS..335..335F Altcode: The calibration pipeline of the level zero images obtained from the Magneto-Optical filters at Two Heights (MOTH II) instrument is presented. MOTH II consists of two 20 cm aperture instruments, each using a Magneto-Optical Filter (MOF): one at 5896 Å (Na D2-line), the other one at 7700 Å (K I-line). MOTH II instruments thus provide full disk line-of-sight Doppler velocity and magnetic field measurements at two heights in the solar atmosphere. The developed MOTH II pipeline employs a set of standard calibration corrections, a correction for signal leakage, due to the non-ideal behavior of the polarizers, and the geometrical registration between the eight images acquired by four CMOS cameras, relative to two components of the signal in two circular polarization states, in each of the two channels. MOTH II data are used to investigate atmospheric dynamics (e.g., internal gravity waves and magneto-acoustic portals) and Space Weather phenomena. Particularly, flare forecasting algorithms, based on the detection of magnetic active regions (ARs) and associated flare probability estimation, are currently under development. The possible matching of MOTH II data with SDO/HMI and SDO/AIA images into a flux rope model, developed in collaboration between Harvard-Smithsonian CfA and MIT Laboratory for Nuclear Science, is being tested. Title: A Probabilistic Approach to the Drag-Based Model Authors: Napoletano, Gianluca; Forte, Roberta; Del Moro, Dario; Pietropaolo, Ermanno; Giovannelli, Luca; Berrilli, Francesco Bibcode: 2018IAUS..335..304N Altcode: Forecasting the time of arrival of a Coronal Mass Ejection at Earth is of critical importance for our high-technology society and for any future manned exploration of the Solar System. As critical as the forecast accuracy is the knowledge of its precision, i.e. the error associated to the estimate. Here a statistical approach to the computation of the time of arrival using the Drag-Based Model is proposed through the introduction of probability distributions, rather than exact values, as input parameters, thus allowing the evaluation of the uncertainty on the forecast. Title: The Ionosphere Prediction Service Authors: Albanese, Carlo; Rodriguez, Filippo; Ronchini, Roberto; di Rollo, Stefano; Berrilli, Francesco; Cristaldi, Alice; Del Moro, Dario; Forte, Roberta; de Franceschi, Giorgiana; Cesaroni, Claudio; Spogli, Luca; Romano, Vincenzo; Aquino, Marcio; Veettil, Sreeja Vadakke; Kalden, Osman; Hutchinson, Michael; Guyader, Eric Bibcode: 2018IAUS..335..352A Altcode: The aim of the Ionosphere Prediction Service (IPS) project is to design and develop a prototype platform to translate the prediction and forecast of the ionosphere effects into a service customized for specific GNSS user communities. The project team is composed by Telespazio (coordinator), Nottingham Scientific Ltd, Telespazio Vega Deutschland, the University of Nottingham, the University of Rome ``Tor Vergata'' and the Italian Istituto Nazionale di Geofisica e Vulcanologia (INGV). The IPS development is conceived of two concurrent activities: prototype service design and development & research activity that will run along the whole project. Service design and development is conceived into four phases: user requirements collection, architecture specification, implementation and validation of the prototype. A sub-activity analyses also the integration feasibility in the Galileo Service center, located in Madrid. The research activity is the scientific backbone of IPS that will provide the models and algorithms for the forecasting products. Title: Occurrence and persistence of magnetic elements in the quiet Sun Authors: Giannattasio, F.; Berrilli, F.; Consolini, G.; Del Moro, D.; Gošić, M.; Bellot Rubio, L. Bibcode: 2018A&A...611A..56G Altcode: 2018arXiv180103871G Context. Turbulent convection efficiently transports energy up to the solar photosphere, but its multi-scale nature and dynamic properties are still not fully understood. Several works in the literature have investigated the emergence of patterns of convective and magnetic nature in the quiet Sun at spatial and temporal scales from granular to global.
Aims: To shed light on the scales of organisation at which turbulent convection operates, and its relationship with the magnetic flux therein, we studied characteristic spatial and temporal scales of magnetic features in the quiet Sun.
Methods: Thanks to an unprecedented data set entirely enclosing a supergranule, occurrence and persistence analysis of magnetogram time series were used to detect spatial and long-lived temporal correlations in the quiet Sun and to investigate their nature.
Results: A relation between occurrence and persistence representative for the quiet Sun was found. In particular, highly recurrent and persistent patterns were detected especially in the boundary of the supergranular cell. These are due to moving magnetic elements undergoing motion that behaves like a random walk together with longer decorrelations ( 2 h) with respect to regions inside the supergranule. In the vertices of the supegranular cell the maximum observed occurrence is not associated with the maximum persistence, suggesting that there are different dynamic regimes affecting the magnetic elements. Title: Autonomous Monitoring of Radiation Environment and Personal Systems for Crew Enhanced SPE Protection (AMORE and PSYCHE) Authors: Narici, L.; Baiocco, G.; Berrilli, F.; Giraudo, M.; Ottolenghi, A.; Rizzo, A.; Salina, G. Bibcode: 2018LPICo2063.3065N Altcode: Understand the relationship between SPE precursors, the related SPE radiation inside the Deep Space Gateway, and the associated risk levels, validating existing models, proposing countermeasures actions via a real time, autonomous intelligent system. Title: A probabilistic approach to the drag-based model Authors: Napoletano, Gianluca; Forte, Roberta; Del Moro, Dario; Pietropaolo, Ermanno; Giovannelli, Luca; Berrilli, Francesco Bibcode: 2018JSWSC...8A..11N Altcode: 2018arXiv180104201N The forecast of the time of arrival (ToA) of a coronal mass ejection (CME) to Earth is of critical importance for our high-technology society and for any future manned exploration of the Solar System. As critical as the forecast accuracy is the knowledge of its precision, i.e. the error associated to the estimate. We propose a statistical approach for the computation of the ToA using the drag-based model by introducing the probability distributions, rather than exact values, as input parameters, thus allowing the evaluation of the uncertainty on the forecast. We test this approach using a set of CMEs whose transit times are known, and obtain extremely promising results: the average value of the absolute differences between measure and forecast is 9.1h, and half of these residuals are within the estimated errors. These results suggest that this approach deserves further investigation. We are working to realize a real-time implementation which ingests the outputs of automated CME tracking algorithms as inputs to create a database of events useful for a further validation of the approach. Title: Comprehensive Analysis of the Geoeffective Solar Event of 21 June 2015: Effects on the Magnetosphere, Plasmasphere, and Ionosphere Systems Authors: Piersanti, Mirko; Alberti, Tommaso; Bemporad, Alessandro; Berrilli, Francesco; Bruno, Roberto; Capparelli, Vincenzo; Carbone, Vincenzo; Cesaroni, Claudio; Consolini, Giuseppe; Cristaldi, Alice; Del Corpo, Alfredo; Del Moro, Dario; Di Matteo, Simone; Ermolli, Ilaria; Fineschi, Silvano; Giannattasio, Fabio; Giorgi, Fabrizio; Giovannelli, Luca; Guglielmino, Salvatore Luigi; Laurenza, Monica; Lepreti, Fabio; Marcucci, Maria Federica; Martucci, Matteo; Mergè, Matteo; Pezzopane, Michael; Pietropaolo, Ermanno; Romano, Paolo; Sparvoli, Roberta; Spogli, Luca; Stangalini, Marco; Vecchio, Antonio; Vellante, Massimo; Villante, Umberto; Zuccarello, Francesca; Heilig, Balázs; Reda, Jan; Lichtenberger, János Bibcode: 2017SoPh..292..169P Altcode: A full-halo coronal mass ejection (CME) left the Sun on 21 June 2015 from active region (AR) NOAA 12371. It encountered Earth on 22 June 2015 and generated a strong geomagnetic storm whose minimum Dst value was −204 nT. The CME was associated with an M2-class flare observed at 01:42 UT, located near disk center (N12 E16). Using satellite data from solar, heliospheric, and magnetospheric missions and ground-based instruments, we performed a comprehensive Sun-to-Earth analysis. In particular, we analyzed the active region evolution using ground-based and satellite instruments (Big Bear Solar Observatory (BBSO), Interface Region Imaging Spectrograph (IRIS), Hinode, Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO), Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), covering Hα , EUV, UV, and X-ray data); the AR magnetograms, using data from SDO/Helioseismic and Magnetic Imager (HMI); the high-energy particle data, using the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) instrument; and the Rome neutron monitor measurements to assess the effects of the interplanetary perturbation on cosmic-ray intensity. We also evaluated the 1 - 8 Å soft X-ray data and the ∼1 MHz type III radio burst time-integrated intensity (or fluence) of the flare in order to predict the associated solar energetic particle (SEP) event using the model developed by Laurenza et al. (Space Weather7(4), 2009). In addition, using ground-based observations from lower to higher latitudes (International Real-time Magnetic Observatory Network (INTERMAGNET) and European Quasi-Meridional Magnetometer Array (EMMA)), we reconstructed the ionospheric current system associated with the geomagnetic sudden impulse (SI). Furthermore, Super Dual Auroral Radar Network (SuperDARN) measurements were used to image the global ionospheric polar convection during the SI and during the principal phases of the geomagnetic storm. In addition, to investigate the influence of the disturbed electric field on the low-latitude ionosphere induced by geomagnetic storms, we focused on the morphology of the crests of the equatorial ionospheric anomaly by the simultaneous use of the Global Navigation Satellite System (GNSS) receivers, ionosondes, and Langmuir probes onboard the Swarm constellation satellites. Moreover, we investigated the dynamics of the plasmasphere during the different phases of the geomagnetic storm by examining the time evolution of the radial profiles of the equatorial plasma mass density derived from field line resonances detected at the EMMA network (1.5 <L <6.5 ). Finally, we present the general features of the geomagnetic response to the CME by applying innovative data analysis tools that allow us to investigate the time variation of ground-based observations of the Earth's magnetic field during the associated geomagnetic storm. Title: The dependence of the [FUV-MUV] colour on solar cycle Authors: Lovric, Mija; Tosone, Federico; Pietropaolo, Ermanno; Del Moro, Dario; Giovannelli, Luca; Cagnazzo, Chiara; Berrilli, Francesco Bibcode: 2017JSWSC...7A...6L Altcode: 2016arXiv160608267L Solar UV variability is extremely relevant for the stratospheric ozone. It has an impact on Earth's atmospheric structure and dynamics through radiative heating and ozone photochemistry. Our goal is to study the slope of the solar UV spectrum in two UV bands important to the stratospheric ozone production. In order to investigate the solar spectral variability, we use data from SOLSTICE (the Solar Stellar Irradiance Comparison Experiment) on board the Solar Radiation and Climate Experiment (SORCE) satellite. Datasets used are far UV (115-180 nm) and middle UV (180-310 nm), as well as the Mg II index (the Bremen composite). We introduce the SOLSTICE [FUV-MUV] colour to study the solar spectral characteristics, as well as to analyse the colour versus Mg II index. To isolate the 11-year scale variation, we used Empirical Mode Decomposition (EMD) on the datasets. The [FUV-MUV] colour strongly correlates with the Mg II index. The [FUV-MUV] colour shows a time-dependent behaviour when plotted versus the Mg II index. To explain this dependence we hypothesize an efficiency reduction of SOLSTICE FUV irradiance using an exponential ageing law. Title: JP3D compression of solar data-cubes: Photospheric imaging and spectropolarimetry Authors: Del Moro, Dario; Giovannelli, Luca; Pietropaolo, Ermanno; Berrilli, Francesco Bibcode: 2017ExA....43...23D Altcode: 2016ExA...tmp...27M; 2017arXiv170506611D Hyperspectral imaging is an ubiquitous technique in solar physics observations and the recent advances in solar instrumentation enabled us to acquire and record data at an unprecedented rate. The huge amount of data which will be archived in the upcoming solar observatories press us to compress the data in order to reduce the storage space and transfer times. The correlation present over all dimensions, spatial, temporal and spectral, of solar data-sets suggests the use of a 3D base wavelet decomposition, to achieve higher compression rates. In this work, we evaluate the performance of the recent JPEG2000 Part 10 standard, known as JP3D, for the lossless compression of several types of solar data-cubes. We explore the differences in: a) The compressibility of broad-band or narrow-band time-sequence; I or V Stokes profiles in spectropolarimetric data-sets; b) Compressing data in [x,y, λ] packages at different times or data in [x,y,t] packages of different wavelength; c) Compressing a single large data-cube or several smaller data-cubes; d) Compressing data which is under-sampled or super-sampled with respect to the diffraction cut-off. Title: The Heat Rejecter for the GREGOR telescope: a prototype for the European Solar Telescope Authors: Berrilli, F.; Del Moro, D. Bibcode: 2017psio.confE..84B Altcode: No abstract at ADS Title: The dependence of the [FUV-MUV] colour index on solar cycle Authors: Lovric, M.; Berrilli, F.; Cagnazzo, C.; Pietropaolo, E.; Del Moro, D.; Giovannelli, L. Bibcode: 2017psio.confE.103L Altcode: No abstract at ADS Title: Space Weather services for flare and CME forecasting supported by a multi instrument database Authors: Berrilli, F.; Casolino, M.; Del Moro, D.; Forte, R.; Giovannelli, L.; Martucci, M.; Mergé, M.; Napoletano, G.; Narici, L.; Pietropaolo, E.; Pucacco, G.; Rizzo, A.; Scardigli, S.; Sparvoli, R. Bibcode: 2017psio.confE.118B Altcode: No abstract at ADS Title: JP3D compression of solar data-cubes: photospheric imaging and spectropolarimetry Authors: Del Moro, Dario; Giovannelli, Luca; Berrilli, Francesco; Pietropaolo, Ermanno; Ermolli, Ilaria; Kiselman, Dan Bibcode: 2017psio.confE.121D Altcode: No abstract at ADS Title: MOTH II calibration pipeline and data merging with SDO/HMI and SDO/AIA Authors: Forte, R.; Jefferies, S.; Pietropaolo, E.; Scardigli, S.; Giovannelli, L.; Del Moro, D.; Berrilli, F. Bibcode: 2017psio.confE.122F Altcode: No abstract at ADS Title: Solar Energetic Particles Events and Human Exploration: Measurements in a Space Habitat Authors: Narici, L.; Berrilli, F.; Casolino, M.; Del Moro, D.; Forte, R.; Giovannelli, L.; Martucci, M.; Mergè, M.; Picozza, P.; Rizzo, A.; Scardigli, S.; Sparvoli, R.; Zeitlin, C. Bibcode: 2016AGUFMSA41B2372N Altcode: Solar activity is the source of Space Weather disturbances. Flares, CME and coronal holes modulate physical conditions of circumterrestrial and interplanetary space and ultimately the fluxes of high-energy ionized particles, i.e., solar energetic particle (SEP) and galactic cosmic ray (GCR) background. This ionizing radiation affects spacecrafts and biological systems, therefore it is an important issue for human exploration of space. During a deep space travel (for example the trip to Mars) radiation risk thresholds may well be exceeded by the crew, so mitigation countermeasures must be employed. Solar particle events (SPE) constitute high risks due to their impulsive high rate dose. Forecasting SPE appears to be needed and also specifically tailored to the human exploration needs. Understanding the parameters of the SPE that produce events leading to higher health risks for the astronauts in deep space is therefore a first priority issue. Measurements of SPE effects with active devices in LEO inside the ISS can produce important information for the specific SEP measured, relative to the specific detector location in the ISS (in a human habitat with a shield typical of manned space-crafts). Active detectors can select data from specific geo-magnetic regions along the orbits, allowing geo-magnetic selections that best mimic deep space radiation. We present results from data acquired in 2010 - 2012 by the detector system ALTEA inside the ISS (18 SPEs detected). We compare this data with data from the detector Pamela on a LEO satellite, with the RAD data during the Curiosity Journey to Mars, with GOES data and with several Solar physical parameters. While several features of the radiation modulation are easily understood by the effect of the geomagnetic field, as an example we report a proportionality of the flux in the ISS with the energetic proton flux measured by GOES, some features appear more difficult to interpret. The final goal of this work is to find the characteristics of solar events leading to highest radiation risks in a human habitat during deep space exploration to best focus the needed forecasting. Title: Analysis of the performances of 45 degrees tilted deformable mirrors for the EST MCAO Authors: Stangalini, Marco; Pedichini, Fernando; Berrilli, Francesco; Del Moro, Dario; Ermolli, Ilaria; Giorgi, Fabrizio Bibcode: 2016SPIE.9909E..7IS Altcode: The European Solar Telescope (EST) will be best suited for very high accuracy polarization measurements. Indeed, its optical design is such that the telescope as a whole does not modify the polarization state of the incoming light. For this reason, a mutually compensating configuration with non-standard 45 degrees tilted deformable mirrors (DMs) is proposed for its multi-conjugated adaptive optics (MCAO) system. We studied such non-standard configuration and the impact of DMs with large incidence angles on the overall performances of the EST MCAO system. In this work we present some preliminary results derived from our study. Title: Chromospheric Heating by Acoustic Waves Compared to Radiative Cooling Authors: Sobotka, M.; Heinzel, P.; Švanda, M.; Jurčák, J.; del Moro, D.; Berrilli, F. Bibcode: 2016ApJ...826...49S Altcode: 2016arXiv160504794S Acoustic and magnetoacoustic waves are among the possible candidate mechanisms that heat the upper layers of the solar atmosphere. A weak chromospheric plage near the large solar pore NOAA 11005 was observed on 2008 October 15, in the Fe I 617.3 nm and Ca II 853.2 nm lines of the Interferometric Bidimemsional Spectrometer attached to the Dunn Solar Telescope. In analyzing the Ca II observations (with spatial and temporal resolutions of 0.″4 and 52 s) the energy deposited by acoustic waves is compared to that released by radiative losses. The deposited acoustic flux is estimated from the power spectra of Doppler oscillations measured in the Ca II line core. The radiative losses are calculated using a grid of seven one-dimensional hydrostatic semi-empirical model atmospheres. The comparison shows that the spatial correlation of the maps of radiative losses and acoustic flux is 72%. In a quiet chromosphere, the contribution of acoustic energy flux to radiative losses is small, only about 15%. In active areas with a photospheric magnetic-field strength between 300 and 1300 G and an inclination of 20°-60°, the contribution increases from 23% (chromospheric network) to 54% (a plage). However, these values have to be considered as lower limits and it might be possible that the acoustic energy flux is the main contributor to the heating of bright chromospheric network and plages. Title: A comparison of void distribution function of two solar minima Authors: Scardigli, Stefano; Berrilli, Francesco; del Moro, Dario; Giovannelli, Luca Bibcode: 2016EGUGA..1817046S Altcode: The latest solar minimum, between cycles 23 and 24 had been exceptionally quiet and long lasting. To investigate the difference between the last two minima, we focused on the magnetic patterns on solar surface as recorded by SOHO/MDI high-resolution magnetograms. We used daily samples of 191 images (August 1996 - February 1997) and 511 images (January 2008 - June 2009) respectively, and considered the void, i.e., magnetic underdense region, distribution function as the indicator of solar activity. To single out voids and to quantify their intrinsic pattern, we applied a fast circle-packing-based algorithm to the high-resolution magnetograms during the solar activity minima. Title: The cycle-dependence of Far-UV and Middle-UV solar emission: EMD analysis of SOLSTICE and Mg II signals Authors: Berrilli, Francesco; Lovric, Mija; Federico, Tosone; Cagnazzo, Chiara; Del Moro, Dario; Pietropaolo, Ermanno Bibcode: 2016EGUGA..1812293B Altcode: The solar Far-UV and Middle-UV variability is extremely relevant for the stratospheric ozone concentration and dynamics. We investigate solar UV variability at decennial time scale using the data of SOLar-STellar Irradiance Comparison Experiment (SOLSTICE) on SORCE and Bremen Mg II composite signal. The Empirical Mode Decomposition (EMD) technique has been applied to Mg II and UV signals to separate intrinsic solar components and focus on 11-y variability. The analysis shows that the star changes the UV spectral distribution during 11-y cycle with a different behaviour during the descending phase of cycle 23 and growing phase of cycle 24. The observed UV major evolution can provide empirically-motivated UV predictions over the cycles. On the other hand, the observed minor differences during the ascending and descending phase of solar cycle can be attributed to physical changes in solar emission or described by an uncorrected time-dependent performance of SOLSTICE UV channels. We shortly discuss both possibilities. Title: N-body model of magnetic flux tubes reconnecting in the solar atmosphere Authors: Giovannelli, L.; Berrilli, F.; Del Moro, D.; Scardigli, S.; Consolini, G.; Stangalini, M.; Giannattasio, F.; Caroli, A.; Pucci, F.; Penza, V. Bibcode: 2016JPhCS.689a2009G Altcode: 2016arXiv160107105G The investigation of dynamics of the small scale magnetic field on the Sun photosphere is necessary to understand the physical processes occurring in the higher layers of solar atmosphere due to the magnetic coupling between the photosphere and the corona. We present a simulation able to address these phenomena investigating the statistics of magnetic loops reconnections. The simulation is based on N-body model approach and is divided in two computational layers. We simplify the convection problem, interpreting the larger convective scale, mesogranulation, as the result of the collective interaction of convective downflow of granular scale. The N-body advection model is the base to generate a synthetic time series of nanoflares produced by interacting magnetic loops. The reconnection of magnetic field lines is the result of the advection of the magnetic footpoints following the velocity field generated by the interacting downflows. The model gives a quantitative idea of how much energy is expected to be released by the reconfiguration of magnetic loops in the quiet Sun. Title: Turbulent convective flows in the solar photospheric plasma Authors: Caroli, A.; Giannattasio, F.; Fanfoni, M.; Del Moro, D.; Consolini, G.; Berrilli, F. Bibcode: 2015JPlPh..81e4914C Altcode: > The origin of the 22-year solar magnetic cycle lies below the photosphere where multiscale plasma motions, due to turbulent convection, produce magnetic fields. The most powerful intensity and velocity signals are associated with convection cells, called granules, with a scale of typically 1 Mm and a lifetime of a few minutes. Small-scale magnetic elements (SMEs), ubiquitous on the solar photosphere, are passively transported by associated plasma flows. This advection makes their traces very suitable for defining the convective regime of the photosphere. Therefore the solar photosphere offers an exceptional opportunity to investigate convective motions, associated with compressible, stratified, magnetic, rotating and large Rayleigh number stellar plasmas. The magnetograms used here come from a Hinode/SOT uninterrupted 25-hour sequence of spectropolarimetric images. The mean-square displacement of SMEs has been modelled with a power law with spectral index . We found for times up to and for times up to . An alternative way to investigate the advective-diffusive motion of SMEs is to look at the evolution of the two-dimensional probability distribution function (PDF) for the displacements. Although at very short time scales the PDFs are affected by pixel resolution, for times shorter than the PDFs seem to broaden symmetrically with time. In contrast, at longer times a multi-peaked feature of the PDFs emerges, which suggests the non-trivial nature of the diffusion-advection process of magnetic elements. A Voronoi distribution analysis shows that the observed small-scale distribution of SMEs involves the complex details of highly nonlinear small-scale interactions of turbulent convective flows detected in solar photospheric plasma. Title: ADAHELI: exploring the fast, dynamic Sun in the x-ray, optical, and near-infrared Authors: Berrilli, Francesco; Soffitta, Paolo; Velli, Marco; Sabatini, Paolo; Bigazzi, Alberto; Bellazzini, Ronaldo; Bellot Rubio, Luis Ramon; Brez, Alessandro; Carbone, Vincenzo; Cauzzi, Gianna; Cavallini, Fabio; Consolini, Giuseppe; Curti, Fabio; Del Moro, Dario; Di Giorgio, Anna Maria; Ermolli, Ilaria; Fabiani, Sergio; Faurobert, Marianne; Feller, Alex; Galsgaard, Klaus; Gburek, Szymon; Giannattasio, Fabio; Giovannelli, Luca; Hirzberger, Johann; Jefferies, Stuart M.; Madjarska, Maria S.; Manni, Fabio; Mazzoni, Alessandro; Muleri, Fabio; Penza, Valentina; Peres, Giovanni; Piazzesi, Roberto; Pieralli, Francesca; Pietropaolo, Ermanno; Martinez Pillet, Valentin; Pinchera, Michele; Reale, Fabio; Romano, Paolo; Romoli, Andrea; Romoli, Marco; Rubini, Alda; Rudawy, Pawel; Sandri, Paolo; Scardigli, Stefano; Spandre, Gloria; Solanki, Sami K.; Stangalini, Marco; Vecchio, Antonio; Zuccarello, Francesca Bibcode: 2015JATIS...1d4006B Altcode: Advanced Astronomy for Heliophysics Plus (ADAHELI) is a project concept for a small solar and space weather mission with a budget compatible with an European Space Agency (ESA) S-class mission, including launch, and a fast development cycle. ADAHELI was submitted to the European Space Agency by a European-wide consortium of solar physics research institutes in response to the "Call for a small mission opportunity for a launch in 2017," of March 9, 2012. The ADAHELI project builds on the heritage of the former ADAHELI mission, which had successfully completed its phase-A study under the Italian Space Agency 2007 Small Mission Programme, thus proving the soundness and feasibility of its innovative low-budget design. ADAHELI is a solar space mission with two main instruments: ISODY: an imager, based on Fabry-Pérot interferometers, whose design is optimized to the acquisition of highest cadence, long-duration, multiline spectropolarimetric images in the visible/near-infrared region of the solar spectrum. XSPO: an x-ray polarimeter for solar flares in x-rays with energies in the 15 to 35 keV range. ADAHELI is capable of performing observations that cannot be addressed by other currently planned solar space missions, due to their limited telemetry, or by ground-based facilities, due to the problematic effect of the terrestrial atmosphere. Title: Recurrent flares in active region NOAA 11283 Authors: Romano, P.; Zuccarello, F.; Guglielmino, S. L.; Berrilli, F.; Bruno, R.; Carbone, V.; Consolini, G.; de Lauretis, M.; Del Moro, D.; Elmhamdi, A.; Ermolli, I.; Fineschi, S.; Francia, P.; Kordi, A. S.; Landi Degl'Innocenti, E.; Laurenza, M.; Lepreti, F.; Marcucci, M. F.; Pallocchia, G.; Pietropaolo, E.; Romoli, M.; Vecchio, A.; Vellante, M.; Villante, U. Bibcode: 2015A&A...582A..55R Altcode: Context. Flares and coronal mass ejections (CMEs) are solar phenomena that are not yet fully understood. Several investigations have been performed to single out their related physical parameters that can be used as indices of the magnetic complexity leading to their occurrence.
Aims: In order to shed light on the occurrence of recurrent flares and subsequent associated CMEs, we studied the active region NOAA 11283 where recurrent M and X GOES-class flares and CMEs occurred.
Methods: We use vector magnetograms taken by HMI/SDO to calculate the horizontal velocity fields of the photospheric magnetic structures, the shear and the dip angles of the magnetic field, the magnetic helicity flux distribution, and the Poynting fluxes across the photosphere due to the emergence and the shearing of the magnetic field.
Results: Although we do not observe consistent emerging magnetic flux through the photosphere during the observation time interval, we detected a monotonic increase of the magnetic helicity accumulated in the corona. We found that both the shear and the dip angles have high values along the main polarity inversion line (PIL) before and after all the events. We also note that before the main flare of X2.1 GOES class, the shearing motions seem to inject a more significant energy than the energy injected by the emergence of the magnetic field.
Conclusions: We conclude that the very long duration (about 4 days) of the horizontal displacement of the main photospheric magnetic structures along the PIL has a primary role in the energy release during the recurrent flares. This peculiar horizontal velocity field also contributes to the monotonic injection of magnetic helicity into the corona. This process, coupled with the high shear and dip angles along the main PIL, appears to be responsible for the consecutive events of loss of equilibrium leading to the recurrent flares and CMEs.

A movie associated to Fig. 4 is available in electronic form at http://www.aanda.org Title: The Sun: the Earth light source Authors: Berrilli, Francesco; Giovannelli, Luca; Del Moro, Dario; Piazzesi, Roberto; Catena, Liu` Maria; Amicucci, Giordano; Vittorio, Nicola Bibcode: 2015EGUGA..1713359B Altcode: We have implemented at Department of Physics of University of Rome Tor Vergata a project called "The Sun: the Earth light source". The project obtained the official endorsement from the IAU Executive Committee Working Group for the International Year of Light. The project, specifically designed for high school students, is focused on the "scientific" study of Sun light by means of a complete acquisition system based on "on the shelf" appropriately CMOS low-cost sensor with free control s/w and self-assembled telescopes. The project (hereafter stage) plan is based on a course of two weeks (60 hours in total). The course contains 20 hours of theoretical lectures, necessary to learn basics about Sun, optics, telescopes and image sensors, and 40 hours of laboratory. During the course, scientists and astronomers share with high schools students, work activities in real research laboratories. High schools teachers are intensely involved in the project. Their role is to share activities with university teachers and realize outreach actions in the home institutions. Simultaneously, they are introduced to innovative teaching methods and the project in this way is regarded as a professional development course. Sun light analysis and Sun-Earth connection through light are the main scientific topics of this project. The laboratory section of the stage is executed in two phases (weeks): First phase aims are the realization of a keplerian telescope and low-cost acquisition system. During this week students are introduced to astronomical techniques used to safety collect and acquire solar light; Second phase aims is the realization of a low-cost instrument to analyse sunlight extracting information about the solar spectrum, solar irradiance and Sun-Earth connection. The proposed stage has been already tested in Italy reached the fifth edition in 2014. Since 2010, the project has been a cornerstone outreach program of the University of Rome Tor Vergata, the Italian Ministry of Education and the National Program for the diffusion of Scientific Degrees (Progetto Lauree Scientifiche or PLS). In the last years has been mainly aimed to underline the connections between Astronomy, Astrophysics and the new materials involved in the astronomical techniques. The Sun has always been used in the course as a key element since the final product was the production of a self-constructed solar telescope able to be used to monitor the solar activity through Wolf's number estimation. In the third edition the project has been extended to other three Universities on the Italian territory: University of l'Aquila, University of Camerino and University of Calabria. Over the years more than 80 students and 50 teachers where directly involved and more than 50 different high schools on all the national territory, reaching thousands of their students in the final dissemination part of the program. 25 telescopes are currently in use in high school institutes all-over Italy. A book describing the project has been published by Springer in 2013 (STUDENTI-RICERCATORI per cinque giorni "Stage a Tor Vergata" Editors: Liù M. Catena, Francesco Berrilli, Ivan Davoli, Paolo Prosposito, ISBN: 978-88-470-5271-0 (Online) ), the link to the book describing the project and reporting student interviews is at: http://link.springer.com/book Title: Super-diffusion versus competitive advection: a simulation Authors: Del Moro, D.; Giannattasio, F.; Berrilli, F.; Consolini, G.; Lepreti, F.; Gošić, M. Bibcode: 2015A&A...576A..47D Altcode: 2015arXiv150105444D Context. Magnetic element tracking is often used to study the transport and diffusion of the magnetic field on the solar photosphere. From the analysis of the displacement spectrum of these tracers, it has recently been agreed that a regime of super-diffusivity dominates the solar surface. Quite habitually this result is discussed in the framework of fully developed turbulence.
Aims: However, the debate whether the super-diffusivity is generated by a turbulent dispersion process, by the advection due to the convective pattern, or even by another process is still open, as is the question of the amount of diffusivity at the scales relevant to the local dynamo process.
Methods: To understand how such peculiar diffusion in the solar atmosphere takes place, we compared the results from two different data sets (ground-based and space-borne) and developed a simulation of passive tracers advection by the deformation of a Voronoi network.
Results: The displacement spectra of the magnetic elements obtained by the data sets are consistent in retrieving a super-diffusive regime for the solar photosphere, but the simulation also shows a super-diffusive displacement spectrum: its competitive advection process can reproduce the signature of super-diffusion.
Conclusions: Therefore, it is not necessary to hypothesize a totally developed turbulence regime to explain the motion of the magnetic elements on the solar surface. Title: Solar storm prediction through flare forecasting based on multi-line magnetograms Authors: Berrilli, Francesco; Del Moro, Dario; Pietropaolo, Ermanno; Jefferies, Stuart Bibcode: 2015EGUGA..1712085B Altcode: The capability to predict the physical conditions in near-Earth space (space weather) is of paramount importance to the European society. Sudden changes in space weather, due to solar storms associated to eruptive events such as coronal mass ejections and flares, can impact the technology we rely on every day. The MOTH instrument, based on magneto-optical filters, is able to perform multi-line, high-cadence synoptic observations of the Sun and solar activity. The multi-line capability means solar atmospheric multi-height analysis capability. As a consequence, MOTH instrument is able to simultaneously evaluate both horizontal and vertical gradients of LOS component of solar magnetic field B. Presently, two telescopes/channels are available at K I 770nm and Na D2 589nm lines with high zero-point stability (about 6 cm/s) and velocity sensitivity of about 7 m/s and magnetic sensitivity of about 5 Gauss in 5 seconds. Such data provide crucial information on how and when solar storms form. We present preliminary analysis of multi-line magnetograms used to test innovative flare forecasting algorithm. Title: Improvements on adaptive optics control approaches: experimental tests of wavefront correction forecasting Authors: Del Moro, Dario; Piazzesi, Roberto; Stangalini, Marco; Giovannelli, Luca; Berrilli, Francesco Bibcode: 2015JATIS...1a9002D Altcode: The FORS (closed loop forecasting system) control algorithm has been already successfully applied to improve the efficiency of a simulated adaptive optics (AO) system. To test its performance in real conditions, we implemented this algorithm in a hardware AO demonstrator, introducing controlled aberrations into the system. We present here the results of introducing into the system both a simple periodic defocus aberration and a real open loop defocus time sequence acquired at the vacuum tower telescope solar telescope. In both cases, FORS yields a significant performance increase, improving the stability of the system in closed-loop conditions and decreasing the amplitude of the residual uncorrected wavefront aberrations. Title: Pair separation of magnetic elements in the quiet Sun Authors: Giannattasio, F.; Berrilli, F.; Biferale, L.; Del Moro, D.; Sbragaglia, M.; Bellot Rubio, L.; Gošić, M.; Orozco Suárez, D. Bibcode: 2014A&A...569A.121G Altcode: 2014arXiv1409.1010G The dynamic properties of the quiet Sun photosphere can be investigated by analyzing the pair dispersion of small-scale magnetic fields (i.e., magnetic elements). By using 25 h-long Hinode magnetograms at high spatial resolution (0.3 arcsec), we tracked 68 490 magnetic element pairs within a supergranular cell near the disk center. The computed pair separation spectrum, calculated on the whole set of particle pairs independently of their initial separation, points out what is known as a super-diffusive regime with spectral index γ = 1.55 ± 0.05, in agreement with the most recent literature, but extended to unprecedented spatial and temporal scales (from granular to supergranular). Furthermore, for the first time, we investigated here the spectrum of the mean square displacement of pairs of magnetic elements, depending on their initial separation r0. We found that there is a typical initial distance above (below) which the pair separation is faster (slower) than the average. A possible physical interpretation of such a typical spatial scale is also provided. Title: Observational evidence for buffeting-induced kink waves in solar magnetic elements Authors: Stangalini, M.; Consolini, G.; Berrilli, F.; De Michelis, P.; Tozzi, R. Bibcode: 2014A&A...569A.102S Altcode: 2014arXiv1408.3987S The role of diffuse photospheric magnetic elements in the energy budget of the upper layers of the Sun's atmosphere has been the recent subject of many studies. This was made possible by the availability of high temporal and spatial resolution observations of the solar photosphere, allowing large numbers of magnetic elements to be tracked to study their dynamics. In this work we exploit a long temporal series of seeing-free magnetograms of the solar photosphere to study the effect of the turbulent convection on the excitation of kink oscillations in magnetic elements. We make use of the empirical mode decomposition technique in order to study the transverse oscillations of several magnetic flux tubes. This technique permits analysis of non-stationary time series like those associated to the horizontal velocities of these flux tubes, which are continuously advected and dispersed by granular flows. Our primary findings reveal the excitation of low frequency modes of kink oscillations, which are subharmonics of a fundamental mode with a 7.6 ± 0.2 min periodicity. These results constitute observational proof of the excitation of kink waves by the buffeting of the convection cells in the solar photosphere, and they are discussed in light of their possible role in the energy budget of the upper Sun's atmosphere. Title: Magnetic pattern at supergranulation scale: the void size distribution Authors: Berrilli, F.; Scardigli, S.; Del Moro, D. Bibcode: 2014A&A...568A.102B Altcode: 2014arXiv1406.5871B The large-scale magnetic pattern observed in the photosphere of the quiet Sun is dominated by the magnetic network. This network, created by photospheric magnetic fields swept into convective downflows, delineates the boundaries of large-scale cells of overturning plasma and exhibits "voids" in magnetic organization. These voids include internetwork fields, which are mixed-polarity sparse magnetic fields that populate the inner part of network cells. To single out voids and to quantify their intrinsic pattern we applied a fast circle-packing-based algorithm to 511 SOHO/MDI high-resolution magnetograms acquired during the unusually long solar activity minimum between cycles 23 and 24. The computed void distribution function shows a quasi-exponential decay behavior in the range 10-60 Mm. The lack of distinct flow scales in this range corroborates the hypothesis of multi-scale motion flows at the solar surface. In addition to the quasi-exponential decay, we have found that the voids depart from a simple exponential decay at about 35 Mm. Title: The effects of AO systems on polarized light Authors: Stangalini, M.; Giovannelli, L.; Del Moro, D.; Berrilli, F.; Piazzesi, R. Bibcode: 2014SPIE.9148E..6PS Altcode: Spectropolarimetry is nowadays one of the most used tool to investigate small scale (100 km) magnetic fields in the Sun's atmosphere. In addition, the forthcoming 4-meter class solar telescopes will provide an unprecedented view of the solar magnetism with an accuracy (10-4) never reached before, and on spatial scales which are at least twice as smaller. For this reason MCAO systems providing high Strehl ratios on a large field of view are being developed. Thus, the study of any possible effect of such AO systems on the polarization accuracy has to be carefully assessed. In this contribution we present preliminary results of laboratory tests conducted with the aim of evaluating possible drawbacks of the use of deformable mirrors on the spectropolarimetric accuracy. Title: Optical cavity characterization of the Tor Vergata Fabry-Pérot interferometer Authors: Giovannelli, Luca; Berrilli, Francesco; Del Moro, Dario; Greco, Vincenzo; Piazzesi, Roberto; Sordini, Andrea; Stangalini, Marco Bibcode: 2014SPIE.9147E..82G Altcode: We report the first optical and control performances of the Tor Vergata Fabry-Ṕerot interferometer prototype designed and realized in the framework of the ADvanced Astronomy for HELIophysics (ADAHELI) solar mission project. The characterization of the the coated surfaces of the two plates defining the optical cavity has been carried out with a Zygo interferometer able to measure the microroughness and global curvature of the cavity. The peak-to-valley errors are compliant with the manufacturer specifications and correspond to λ/70 and λ/80 @632.8 nm respectively. In addition, we present a first estimate of the interferometer spectral stability in stable open-air condition. A spectral uncertainty equal to 0.95 pm is found as the typical RMS over one hour of the passband central wavelength position. Title: Diffusion of Magnetic Elements in a Supergranular Cell Authors: Giannattasio, F.; Stangalini, M.; Berrilli, F.; Del Moro, D.; Bellot Rubio, L. Bibcode: 2014ApJ...788..137G Altcode: 2014arXiv1405.0677G Small scale magnetic fields (magnetic elements) are ubiquitous in the solar photosphere. Their interaction can provide energy to the upper atmospheric layers, and contribute to heat the solar corona. In this work, the dynamic properties of magnetic elements in the quiet Sun are investigated. The high number of magnetic elements detected in a supergranular cell allowed us to compute their displacement spectrum lang(Δr)2rangvpropτγ (with γ > 0, and τ the time since the first detection), separating the contribution of the network (NW) and the internetwork (IN) regions. In particular, we found γ = 1.27 ± 0.05 and γ = 1.08 ± 0.11 in NW (at smaller and larger scales, respectively), and γ = 1.44 ± 0.08 in IN. These results are discussed in light of the literature on the topic, as well as the implications for the build-up of the magnetic network. Title: The relativistic solar particle event of May 17th, 2012 observed on board the International Space Station Authors: Berrilli, Francesco; Casolino, Marco; Del Moro, Dario; Di Fino, Luca; Larosa, Marianna; Narici, Livio; Piazzesi, Roberto; Picozza, Piergiorgio; Scardigli, Stefano; Sparvoli, Roberta; Stangalini, Marco; Zaconte, Veronica Bibcode: 2014JSWSC...4A..16B Altcode: High-energy charged particles represent a severe radiation risk for astronauts and spacecrafts and could damage ground critical infrastructures related to space services. Different natural sources are the origin of these particles, among them galactic cosmic rays, solar energetic particles and particles trapped in radiation belts. Solar particle events (SPE) consist in the emission of high-energy protons, alpha-particles, electrons and heavier particles from solar flares or shocks driven by solar plasma propagating through the corona and interplanetary space. Ground-level enhancements (GLE) are rare solar events in which particles are accelerated to near relativistic energies and affect space and ground-based infrastructures. During the current solar cycle 24 a single GLE event was recorded on May 17th, 2012 associated with an M5.1-class solar flare. The investigation of such a special class of solar events permits us to measure conditions in space critical to both scientific and operational research. This event, classified as GLE71, was detected on board the International Space Station (ISS) by the active particle detectors of the ALTEA (Anomalous Long Term Effects in Astronauts) experiment. The collected data permit us to study the radiation environment inside the ISS. In this work we present the first results of the analysis of data acquired by ALTEA detectors during GLE71 associated with an M5.1-class solar flare. We estimate the energy loss spectrum of the solar particles and evaluate the contribution to the total exposure of ISS astronauts to solar high-energy charged particles. Title: Solar particle event detected by ALTEA on board the International Space Station. The March 7th, 2012 X5.4 flare Authors: Di Fino, Luca; Zaconte, Veronica; Stangalini, Marco; Sparvoli, Roberta; Picozza, Piergiorgio; Piazzesi, Roberto; Narici, Livio; Larosa, Marianna; Del Moro, Dario; Casolino, Marco; Berrilli, Francesco; Scardigli, Stefano Bibcode: 2014JSWSC...4A..19D Altcode: Context. Solar activity poses substantial risk for astronauts of the International Space Station (ISS) both on board and during extravehicular activity. An accurate assessment of the charged radiation flux in space habitats is necessary to determine the risk and the specific type of radiation exposure of ISS crew members, and to develop ways to protect future crews for planetary missions, even in case of high solar activity.
Aims: To reduce the present-day uncertainties about the nature and magnitude of the particle fluxes in space habitats during a solar event, it is fundamental to measure those fluxes in situ.
Methods: The ALTEA (Anomalous Long Term Effects on Astronauts) experiment on board the ISS is an active detector composed of six silicon telescopes and is able to follow the dynamics of the radiation flux. During its operation in 2012 a number of flux peaks were detected in correspondence with solar events.
Results: We present in this work an analysis of the ALTEA data measured during the March 7th, 2012 solar event, produced by NOAA AR11429.
Conclusions: During this event, the flux was enhanced tenfold with respect to ``quiet Sun'' conditions, producing strong dose increases at high geomagnetic latitudes. Title: An Estimate of Chromospheric Heating by Acoustic Waves Authors: Sobotka, M.; Švanda, M.; Jurčak, J.; Heinzel, P.; Del Moro, D.; Berrilli, F. Bibcode: 2014CEAB...38...53S Altcode: Several mechanisms may heat the solar chromosphere: acoustic waves, magnetoacoustic waves (slow, fast, and Alfvén waves), and small-scale magnetic reconnections. Based on observations in the Ca II 854.2 nm line, the contribution of acoustic waves to the heating of quiet and plage regions in the chromosphere is discussed. The energy released by radiative losses is compared with the energy deposited by acoustic waves. Radiative losses are computed using a grid of six semi-empirical models VAL A--F. The deposited acoustic flux is calculated using power spectra of Doppler oscillations measured in the Ca~II line core. The comparison shows that the spatial correlation of maps of radiative losses and acoustic flux is 70 %. The deposited acoustic flux provides at least 25--30~% of the energy radiated in the quiet chromosphere and 50~% in plage regions. Title: Velocity and Temperature Response Functions of 61 Photospheric Lines in the Near-Infrared H Band (1500 - 1800 nm) - II Authors: Penza, V.; Berrilli, F. Bibcode: 2014SoPh..289...27P Altcode: We present a list of 61 solar photospheric lines in the near-infrared H-band (1500 - 1800 nm), obtained by synthesis under the LTE approximation, and compute the corresponding velocity and temperature response functions (RF) in the line core and depth-integrated RFs as a function of wavelength. In particular, we computed the core formation heights and the ranges of atmospheric layers where thermodynamic perturbations are dominant. Moreover, we indicate the wavelength where the line is more sensitive to thermodynamic variations and quantify this sensitivity. This list is the extension of a previous work of Penza and Berrilli (Solar Phys.277, 227, 2012). Title: Dynamics of the solar atmosphere above a pore with a light bridge Authors: Sobotka, M.; Švanda, M.; Jurčák, J.; Heinzel, P.; Del Moro, D.; Berrilli, F. Bibcode: 2013A&A...560A..84S Altcode: 2013arXiv1309.7790S Context. Solar pores are small sunspots lacking a penumbra that have a prevailing vertical magnetic-field component. They can include light bridges at places with locally reduced magnetic field. Like sunspots, they exhibit a wide range of oscillatory phenomena.
Aims: A large isolated pore with a light bridge (NOAA 11005) is studied to obtain characteristics of a chromospheric filamentary structure around the pore, to analyse oscillations and waves in and around the pore, and to understand the structure and brightness of the light bridge.
Methods: Spectral imaging observations in the line Ca II 854.2 nm and complementary spectropolarimetry in Fe I lines, obtained with the DST/IBIS spectrometer and HINODE/SOT spectropolarimeter, were used to measure photospheric and chromospheric velocity fields, oscillations, waves, the magnetic field in the photosphere, and acoustic energy flux and radiative losses in the chromosphere.
Results: The chromospheric filamentary structure around the pore has all important characteristics of a superpenumbra: it shows an inverse Evershed effect and running waves, and has a similar morphology and oscillation character. The granular structure of the light bridge in the upper photosphere can be explained by radiative heating. Acoustic waves leaking up from the photosphere along the inclined magnetic field in the light bridge transfer enough energy flux to balance the entire radiative losses of the light-bridge chromosphere.
Conclusions: A penumbra is not a necessary condition for the formation of a superpenumbra. The light bridge is heated by radiation in the photosphere and by acoustic waves in the chromosphere. Title: The spectrum of kink-like oscillations of solar photospheric magnetic elements Authors: Stangalini, M.; Berrilli, F.; Consolini, G. Bibcode: 2013A&A...559A..88S Altcode: 2013arXiv1310.2472S Recently, the availability of new high spatial and temporal resolution observations of the solar photosphere has allowed for the study of the oscillations in small magnetic elements. Small magnetic elements have been found to host a rich variety of oscillations detectable as intensity, longitudinal, or transverse velocity fluctuations that have been interpreted as magneto-hydrodynamic (MHD) waves. Small magnetic elements, at or below the current spatial resolution achieved by modern solar telescopes, are thought to play a relevant role in the energy budget of the upper layers of the Sun's atmosphere, as they are found to cover a significant fraction of the solar photosphere. Unfortunately, the limited temporal length and/or cadence of the data sets or the presence of seeing-induced effects have prevented accurate estimates of the power spectra of kink-like oscillations in small magnetic elements so far. Motivated by this, we studied kink-like oscillations in small magnetic elements, by exploiting very long duration and high cadence data acquired with the Solar Optical Telescope on board the Hinode satellite. In this paper, we present the results of a statistical study of the power spectral density of kink-like oscillations. We found that small magnetic elements exhibit a large number of spectral features in the range 1-12 mHz. Most of these spectral features are not shared among magnetic elements rather they represent a unique signature of each magnetic element itself. Title: Diffusion of Solar Magnetic Elements up to Supergranular Spatial and Temporal Scales Authors: Giannattasio, F.; Del Moro, D.; Berrilli, F.; Bellot Rubio, L.; Gošić, M.; Orozco Suárez, D. Bibcode: 2013ApJ...770L..36G Altcode: 2013arXiv1305.4006G The study of spatial and temporal scales on which small magnetic structures (magnetic elements) are organized in the quiet Sun may be approached by determining how they are transported on the solar photosphere by convective motions. The process involved is diffusion. Taking advantage of Hinode high spatial resolution magnetograms of a quiet-Sun region at the disk center, we tracked 20,145 magnetic elements. The large field of view (~50 Mm) and the long duration of the observations (over 25 hr without interruption at a cadence of 90 s) allowed us to investigate the turbulent flows at unprecedented large spatial and temporal scales. In the field of view an entire supergranule is clearly recognizable. The magnetic element displacement spectrum shows a double-regime behavior: superdiffusive (γ = 1.34 ± 0.02) up to granular spatial scales (~1500 km) and slightly superdiffusive (γ = 1.20 ± 0.05) up to supergranular scales. Title: On the asymmetry of velocity oscillation amplitude in bipolar active regions Authors: Giannattasio, F.; Stangalini, M.; Del Moro, D.; Berrilli, F. Bibcode: 2013A&A...550A..47G Altcode: 2012arXiv1212.2736G The velocity field in the lower solar atmosphere undergoes strong interactions with magnetic fields. Many authors have pointed out that power is reduced by a factor between two and three within magnetic regions, depending on frequency, depth, the radius, and the magnetic strength of the flux tube. Many mechanisms have been proposed to explain the observations. In this work, Solar Dynamics Observatory (SDO) dopplergrams and magnetograms of 12 bipolar active regions (βARs) at a 45-s cadence are used to investigate the relation between velocity fluctuations and magnetic fields. We show that there is an asymmetry within βARs, with the velocity oscillation amplitude being more suppressed in the leading polarities than in the trailing polarities. Also, the strongest magnetic fields do not completely suppress the five-minute oscillation amplitude, even in the spot's innermost umbrae. Title: Multiscale Magnetic Underdense Regions on the Solar Surface: Granular and Mesogranular Scales Authors: Berrilli, F.; Scardigli, S.; Giordano, S. Bibcode: 2013SoPh..282..379B Altcode: 2012arXiv1208.2669B The Sun is a non-equilibrium, dissipative system subject to an energy flow that originates in its core. Convective overshooting motions create temperature and velocity structures that show a temporal and spatial multiscale evolution. As a result, photospheric structures are generally considered to be a direct manifestation of convective plasma motions. The plasma flows in the photosphere govern the motion of single magnetic elements. These elements are arranged in typical patterns, which are observed as a variety of multiscale magnetic patterns. High-resolution magnetograms of the quiet solar surface revealed the presence of multiscale magnetic underdense regions in the solar photosphere, commonly called voids, which may be considered to be a signature of the underlying convective structure. The analysis of such patterns paves the way for the investigation of all turbulent convective scales, from granular to global. In order to address the question of magnetic structures driven by turbulent convection at granular and mesogranular scales, we used a voids-detection method. The computed distribution of void length scales shows an exponential behavior at scales between 2 and 10 Mm and the absence of features at mesogranular scales. The absence of preferred scales of organization in the 2 - 10 Mm range supports the multiscale nature of flows on the solar surface and the absence of a mesogranular convective scale. Title: The multiscale nature of magnetic pattern on the solar surface Authors: Scardigli, S.; Del Moro, D.; Berrilli, F. Bibcode: 2013MmSAI..84..440S Altcode: Multiscale magnetic underdense regions (voids) appear in high resolution magnetograms of quiet solar surface. These regions may be considered a signature of the underlying convective structure. The study of the associated pattern paves the way for the study of turbulent convective scales from granular to global. In order to address the question of magnetic pattern driven by turbulent convection we used a novel automatic void detection method to calculate void distributions. The absence of preferred scales of organization in the calculated distributions supports the multiscale nature of flows on the solar surface and the absence of preferred convective scales. Title: A solar flares X-ray polarimeter Authors: Fabiani, S.; Bellazzini, R.; Berrilli, F.; Brez, A.; Costa, E.; Muleri, F.; Pinchera, M.; Rubini, A.; Soffitta, P.; Spandre, G. Bibcode: 2013MmSAI..84..422F Altcode: The measurement of X-ray polarization from solar flares is a scientific challenge which did not give any exhaustive result so far. X-ray polarimetry would be a probe of the solar flares physics making possible to study directly the magnetic reconnection and particle acceleration in the solar atmosphere of active regions where flares take place. New instrumentation specifically developed to measure the polarization of X-ray is needed to obtain results with adequate significance. The photoelectric polarimeter Gas Pixel Detector (GPD), originally developed to observe astrophysical sources other then the Sun, can address also solar science. The recent development of a new detector prototype effective in the hard X-rays makes suitable this polarimeter to examine the solar flares spectral region in which typically the non-thermal bremsstrahlung emission, expected to be highly polarized, arises with respect to the thermal bremsstrahlung whose polarization is expected to be marginal. The GPD versatility and small size make such an instrument suitable to fly on board of small space missions. Title: From solar physics to astrophysics: the Sun as Rosetta stone for understanding astrophysical processes & The Sun: new tools and ideas in observational solar astrophysics: European week of Astronomy and Space Science Authors: Berrilli, F.; Ermolli, I.; Zuccarello, F. Bibcode: 2013MmSAI..84..281B Altcode: No abstract at ADS Title: Velocity oscillation amplitude in bipolar active regions through SDO observations Authors: Giannattasio, F.; Stangalini, M.; Del Moro, D.; Berrilli, F. Bibcode: 2013MmSAI..84..351G Altcode: Since their discovery, velocity oscillations in the lower solar atmosphere have been observed to interact with magnetic fields. The nature of this interaction, and the mechanisms that channel the energy to the upper layers, represent a crucial issue for the corona heating. In this work, we use SDO dopplergrams and magnetograms of 12 bipolar active regions (beta ARs) to study the relation between velocity oscillation amplitude and magnetic field. We find that the velocity oscillation amplitude depends not only on the magnetic field strength, but also on its polarity. Title: Spectro-polarimetric Observations of Moving Magnetic Features around a Pore Authors: Zuccarello, F.; Berrilli, F.; Criscuoli, S.; Del Moro, D.; Ermolli, I.; Giannattasio, F.; Giorgi, F.; Romano, P.; Viticchiè, B. Bibcode: 2012ASPC..463...51Z Altcode: Moving Magnetic Features (MMFs) are small-size magnetic elements that are seen to stream-out from sunspots. Although several observations suggest that MMFs are closely related to the existence and presence of penumbral filaments, there are some very few observations that report MMFs streaming from pores and sunspots after the penumbra has disappeared. Here we report on the first high spectral, spatial and temporal resolution observations of type II and III MMFs streaming out from a small pore and compare our results with previous observations of features streaming out from penumbrae. We analyzed spectro-polarimetric observations of NOAA 11005 acquired with the IBIS instrument at the Dunn Solar Telescope in the Fe I 617.3 nm and the Ca II 854.2 nm spectral lines, and in the G-band. We show that the characteristics of the investigated MMFs agree with those reported in the literature for MMFs which stream out from spots with penumbrae. We believe that our results provide new information that might be helpful in the future development and upgrade of numerical modeling of the generation of MMFs in the lack of a penumbra. Title: IBIS: High-Resolution Multi-Height Observations and Magnetic Field Retrieval Authors: Del Moro, D. .; Berrilli, F.; Stangalini, M.; Giannattasio, F.; Piazzesi, R.; Giovannelli, L.; Viticchiè, B.; Vantaggiato, M.; Sobotka, M.; Jurčák, J.; Criscuoli, S.; Giorgi, F.; Zuccarello, F. Bibcode: 2012ASPC..463...33D Altcode: IBIS (Interferometric BIdimensional Spectrometer) allows us to measure the four Stokes parameters in several spectroscopic lines with high spatial and spectral resolutions. With this information, we can retrieve both the dynamics and the magnetic field at different layers of the Photosphere and Chromosphere. The high spectral, spatial and temporal resolutions and the polarimetric sensitivity of IBIS allows us to study different phenomena taking place in the solar atmosphere with new tools. As an example, we highlight some applications of IBIS observations and analysis:
· Radiative and dynamical properties of Photospheric Bright Points versus their magnetic field concentration.
· Close up analysis of magnetic, velocity and temperature field in a solar pore.
· MHD wave propagation from the photosphere to the chromosphere in complex magnetic configuration. Title: Magnetic underdense regions and multiscale convection on the solar surface Authors: Berrilli, F.; Scardigli, S.; Del Moro, D. Bibcode: 2012AGUFMSH51A2191B Altcode: The turbulent convective flows on the solar surface govern the motion of magnetic elements. Such elements are arranged in typical patterns which are observed as a variety of multiscale magnetic underdense regions (voids). We investigate the physics of multiscale convection on Sun's surface, characterized by the coexistence of large-scale flow associated with supergiant cells and supergranules, and small-scale photospheric convection (i.e., granulation). The multiscale nature of solar convection is studied using the Void Distribution Function (VDF) calculated using an automatic void-searching algorithm for two-dimensional solar magnetograms. Exponential laws for the VDF as well as two regimes of convection are derived as a function of spatial scale. Our results have ruled out the presence of intrinsic convection scales in the range 5-60 Mm and support the presence of a quasi-continuous spectrum of flows on all scales from granular to global. Title: Turbulent diffusion on the solar photosphere through 24-hour continuous observations of magnetic elements Authors: Giannattasio, F.; Berrilli, F.; Del Moro, D.; Bellot Rubio, L.; Orozco Suarez, D.; Gosic, M. Bibcode: 2012AGUFMSH13A2242G Altcode: Solar atmosphere is a unique laboratory for the study of turbulent flows under extreme conditions (e.g. very high Reynolds numbers). The turbulent nature of the flow may be approached by determining how magnetic flux elements are transported on the solar surface, and measuring the spatio-temporal scales on which these small magnetic structures are organized. The process involved is diffusion. Several works explored this topic, both by simulations and observations, and the results are often contradictory, ranging from fully-developed turbulent scenarios to normal-diffusive motions. We analyze 24-hour continuous Hinode SOT observations of a supergranular region (for the first time these long scales are explored), studying the evolution of the mutual distance between magnetic element pairs and its scaling laws, in order to investigate the diffusion process. We find a super-diffusive behavior, with a gamma index depending on the spatial scale selected. Title: High cadence spectropolarimetry of moving magnetic features observed around a pore Authors: Criscuoli, S.; Del Moro, D.; Giannattasio, F.; Viticchié, B.; Giorgi, F.; Ermolli, I.; Zuccarello, F.; Berrilli, F. Bibcode: 2012A&A...546A..26C Altcode: 2012arXiv1208.2039C Context. Moving magnetic features (MMFs) are small-size magnetic elements that are seen to stream out from sunspots, generally during their decay phase. Several observational results presented in the literature suggest them to be closely related to magnetic filaments that extend from the penumbra of the parent spot. Nevertheless, few observations of MMFs streaming out from spots without penumbra have been reported. The literature still lacks analyses of the physical properties of these features.
Aims: We investigate physical properties of monopolar MMFs observed around a small pore that had developed penumbra in the days preceding our observations and compare our results with those reported in the literature for features observed around sunspots.
Methods: We analyzed NOAA 11005 during its decay phase with data acquired at the Dunn Solar Telescope in the Fe i 617.3 nm and the Ca ii 854.2 nm spectral lines with IBIS, and in the G-band. The field of view showed monopolar MMFs of both polarities streaming out from the leading negative polarity pore of the observed active region. Combining different analyses of the data, we investigated the temporal evolution of the relevant physical quantities associated with the MMFs as well as the photospheric and chromospheric signatures of these features.
Results: We show that the characteristics of the investigated MMFs agree with those reported in the literature for MMFs that stream out from spots with penumbrae. Moreover, observations of at least two of the observed features suggest them to be manifestations of emerging magnetic arches.

Appendices A and B, and a movie are available in electronic form at http://www.aanda.org Title: A Comparative Analysis of Photospheric Bright Points in an Active Region and in the Quiet Sun Authors: Romano, P.; Berrilli, F.; Criscuoli, S.; Del Moro, D.; Ermolli, I.; Giorgi, F.; Viticchié, B.; Zuccarello, F. Bibcode: 2012SoPh..280..407R Altcode: 2012SoPh..tmp...26R We present a comparative study of photometric and dynamic properties of photospheric bright points (BPs) observed at the disk centre in the active region (AR) NOAA 10912 and in the quiet Sun. We found that the average concentration of BPs is 54% larger in the AR than in the quiet Sun. We also measure a decrease of the BP concentration and an increase of their size moving away from the AR centre. However, these variations can be ascribed to the variation of the spatial resolution and image quality in the field of view of the AR dataset. We also found that BPs in the quiet Sun are associated with larger downflow motions than those measured within the AR. Finally, from our measurements of contrast and velocity along the line of sight, we deduced that BPs are less bright in high magnetic flux density regions than in quiet regions, due to a lower efficiency of convection in the former regions. Title: Performance of an Ar-DME imaging photoelectric polarimeter Authors: Fabiani, S.; Bellazzini, R.; Berrilli, F.; Brez, A.; Costa, E.; Minuti, M.; Muleri, F.; Pinchera, M.; Rubini, A.; Soffitta, P.; Spandre, G. Bibcode: 2012SPIE.8443E..1CF Altcode: The possibility to perform polarimetry in the soft X-ray energy band (2-10 keV) with the Gas Pixel Detector, filled with low Z mixtures, has been widely explored so far. The possibility to extend the technique to higher energies, in combination with multilayer optics, has been also hypothesized in the past, on the basis of simulations. Here we present a recent development to perform imaging polarimetry between 6 and 35 keV, employing a new design for the GPD, filled with a Ar-DME gas mixture at high pressure. In order to improve the efficiency by increasing the absorption gap, while preserving a good parallel electric field, we developed a new configuration characterized by a wider gas cell and a wider GEM. The uniform electric field allows to maintain high polarimetric capabilities without any decrease of spectroscopic and imaging properties. We present the first measurements of this prototype showing that it is now possible to perform imaging and spectro-polarimetry of hard X-ray sources. Title: Testing of the "Tor Vergata" Fabry-Pérot interferometer prototype Authors: Giovannelli, Luca; Berrilli, Francesco; Cocciolo, Martina; Del Moro, Dario; Egidi, Alberto; Piazzesi, Roberto; Stangalini, Marco Bibcode: 2012SPIE.8446E..3QG Altcode: In this contribution we present preliminary mechanical and optical tests of the Fabry-Ṕerot interferometer pro- totype developed at the "Tor Vergata" University Solar Physics Laboratory. Fabry-Ṕerot narrow filters are of great interest for the study of extended astronomical sources, such as the solar photosphere and chromosphere. The high transparency of the instrument allows for the necessary high time-resolution for fast dynamic processes observations. A dedicated software has been developed to control both coarse and fine piezo-actuated move- ments, allowing for fast (1ms) tuning capabilities. General mechanical behaviour has been tested for use at the focal plane of ground based telescopes and in the perspective of a new space-qualified prototype. Title: Experimental test of turbulence prediction algorithms Authors: Piazzesi, Roberto; Stangalini, Marco; Del Moro, Dario; Berrilli, Francesco Bibcode: 2012SPIE.8447E..35P Altcode: A forecasting algorithm (FORS) based on Auto Regressive Moving Average (ARMA) processes was developed to correctly model stationary processes and was applied in simulations to the problem of improving the efficiency of an adaptive optics (AO) system. We present here a hardware demonstrator developed at the Solar Physics Laboratory of the University of Rome Tor Vergata where this algorithm has been implemented. An AO system has been deployed to test the efficiency of the algorithm, in which controlled aberrations are introduced in the system and the efficiency of the correction is measured. The demonstrator has proved that there is a significant performance gain by using the FORS algorithm. Title: Physical properties of Moving Magnetic Features observed around a pore Authors: Criscuoli, S.; Del Moro, D.; Giannattasio, F.; Viticchié, B.; Giorgi, F.; Ermolli, I.; Zuccarello, F.; Berrilli, F. Bibcode: 2012EAS....55...87C Altcode: Movies of magnetograms of sunspots often show small-size magnetic patches that move radially away and seem to be expelled from the field of the spot. These patches are named Moving Magnetic Features (MMFs). They have been mostly observed around spots and have been interpreted as manifestations of penumbral filaments. Nevertheless, few observations of MMFS streaming out from spots without penumbra have been reported. He we investigate the physical properties of MMFs observed around the field of a pore derived by the analyses of high spectral, spatial and temporal resolution data acquired at the Dunn Solar Telescope with IBIS. We find that the main properties of the investigated features agree with those reported for MMFs observed around regular spots. These results indicate that an improvement of current numerical simulations is required to understand the generation of MMFs in the lack of penumbrae. Title: Stokes V Asymmetries in the Quiet Sun Authors: Viticchié, B.; Sanchez Almeida, J.; Moro, D. D.; Berrilli, F. Bibcode: 2012ASPC..455..271V Altcode: Stokes profiles emerging from the magnetized quiet photosphere and observed by the Solar Optical Telescope (SOT) spectropolarimeter (SP) aboard the Hinode satellite present a large variety of complex shapes. These are indicative of unresolved magnetic structures and/or gradients along the line of sight that have been overlooked in the inversion analyses performed so far. The interpretation of the complex shapes of SOT/SP Stokes V profiles for the understanding of the quiet Sun magnetism must be seriously considered in the near future. In fact, Stokes V profiles significantly deviating from an antisymmetric shape are rather common in the quiet Sun and, in particular, in intranetwork (IN) regions. Here we present the results of the analysis of the shapes of SOT/SP Stokes V profiles performed through a k-means classification. Such an analysis aims at defining different profile classes representative of SOT/SP polarization measurements. We found that about 35 classes can be defined from quiet Sun measurements. Among these, two main subsets can be recognized: network profiles and IN profiles. Approximately 34% of quiet Sun profiles present important asymmetries. From such results, it follows that new inversion techniques able to reproduce line asymmetries must be considered in future analyses of Hinode SOT/SP measurements. The number of line shapes to be reproduced by such analyses is finite and small. Title: Velocity and Temperature Response Functions of 77 Near-Infrared (800 - 1400 nm) Photospheric Lines - I Authors: Penza, V.; Berrilli, F. Bibcode: 2012SoPh..277..227P Altcode: We present a new list of solar photospheric lines in the near-infrared (NIR) region obtained by synthesis under local thermodynamic equilibrium (LTE) approximation. We give novel velocity and temperature response functions (RFs) for 77 lines over the spectral range 800 - 1400 nm. Using these RFs, we are able to obtain for each line the core formation height and the range of atmospheric layers where thermodynamic perturbations are dominant. Moreover, by using the depth-integrated RFs, we give an indication of the dependence on the wavelength of the RFs and quantify their sensitivity to thermodynamic variations. The NIR region represents a significant source of interest for spectroscopic and polarimetric studies. Indeed, at these wavelengths we explore the deeper photospheric layers, and the Zeeman splitting is larger than in the visible range. Title: Solar magnetism eXplorer (SolmeX). Exploring the magnetic field in the upper atmosphere of our closest star Authors: Peter, Hardi; Abbo, L.; Andretta, V.; Auchère, F.; Bemporad, A.; Berrilli, F.; Bommier, V.; Braukhane, A.; Casini, R.; Curdt, W.; Davila, J.; Dittus, H.; Fineschi, S.; Fludra, A.; Gandorfer, A.; Griffin, D.; Inhester, B.; Lagg, A.; Landi Degl'Innocenti, E.; Maiwald, V.; Sainz, R. Manso; Martínez Pillet, V; Matthews, S.; Moses, D.; Parenti, S.; Pietarila, A.; Quantius, D.; Raouafi, N. -E.; Raymond, J.; Rochus, P.; Romberg, O.; Schlotterer, M.; Schühle, U.; Solanki, S.; Spadaro, D.; Teriaca, L.; Tomczyk, S.; Trujillo Bueno, J.; Vial, J. -C. Bibcode: 2012ExA....33..271P Altcode: 2011arXiv1108.5304P; 2011ExA...tmp..134P The magnetic field plays a pivotal role in many fields of Astrophysics. This is especially true for the physics of the solar atmosphere. Measuring the magnetic field in the upper solar atmosphere is crucial to understand the nature of the underlying physical processes that drive the violent dynamics of the solar corona—that can also affect life on Earth. SolmeX, a fully equipped solar space observatory for remote-sensing observations, will provide the first comprehensive measurements of the strength and direction of the magnetic field in the upper solar atmosphere. The mission consists of two spacecraft, one carrying the instruments, and another one in formation flight at a distance of about 200 m carrying the occulter to provide an artificial total solar eclipse. This will ensure high-quality coronagraphic observations above the solar limb. SolmeX integrates two spectro-polarimetric coronagraphs for off-limb observations, one in the EUV and one in the IR, and three instruments for observations on the disk. The latter comprises one imaging polarimeter in the EUV for coronal studies, a spectro-polarimeter in the EUV to investigate the low corona, and an imaging spectro-polarimeter in the UV for chromospheric studies. SOHO and other existing missions have investigated the emission of the upper atmosphere in detail (not considering polarization), and as this will be the case also for missions planned for the near future. Therefore it is timely that SolmeX provides the final piece of the observational quest by measuring the magnetic field in the upper atmosphere through polarimetric observations. Title: Three-minute wave enhancement in the solar photosphere Authors: Stangalini, M.; Giannattasio, F.; Del Moro, D.; Berrilli, F. Bibcode: 2012A&A...539L...4S Altcode: 2012arXiv1202.1384S It is a well-known result that the power of five-minute oscillations is progressively reduced by magnetic fields in the solar photosphere. Many authors have pointed out that this could be due to a complex interaction of many processes: opacity effects, MHD mode conversion, and intrinsically weaker acoustic emissivity in strong magnetic fields. While five-minute oscillations predominate in the photosphere, it has been shown that in the chromosphere three-minute oscillations are more common. Two main theories have been proposed to explain the presence of the latter oscillations based upon resonance filtering in the atmospheric cavity and non-linear interactions. In this work, we show, through the analysis of IBIS observations of a solar pore in the photospheric Fe I 617.3 nm line, that three-minute waves are already present at the height of formation of this line, their amplitude depends on the magnetic field strength, and they are strictly confined to the umbral region. Title: Algorithm for real time flare detection . Authors: Piazzesi, R.; Berrilli, F.; Del Moro, D.; Egidi, A. Bibcode: 2012MSAIS..19..109P Altcode: A real time flare searching system has been developed at the University of Tor Vergata. The system is comprised of a CMOS camera (C-CAM BCi5) which captures full disk H-alpha solar images and a detection algorithm. The system has been installed for test at the Solar Station of the Tor Vergata University. The algorithm detects in real time the onset of solar flares by analysing intensity variations in the images. The basic parameters for the definition of a flare onset (intensity gradient and threshold) are user-tunable. The algorithm has been developed in the National Instruments Labview environment. It is prepared for integration with different camera systems at different observatories, and possibily at the future EST (European Solar Telescope) and particularly at the AFDT (Auxiliary Full Disk Telescope) which will provide full disk images in three spectral bands, including H-alpha. The system has been active during the past year and a half at the Tor Vergata Solar Station. Due to the current solar minimum no flare activity was available and the algorithm is currently being tested on Solar H-alpha images taken at the Kanzelhoe Observatory. Title: A model for magnetic flux transport. Authors: Volpes, L.; Berrilli, F.; Del Moro, D.; Viticchié, B. Bibcode: 2012MSAIS..19..125V Altcode: One of the most noticeable manifestation of Sun's variable activity consists in the increasing and decreasing number of active regions covering the solar photosphere throughout each cycle. Active regions are thought to be the product of the emergence of buoyant flux tubes formed at the base of the convectione zone; once emerged, their cross sections with the photosphere are observed as magnetic concentrations forming active regions. We present a model in which the evolution of a bipolar magnetic structure is due to the advection of magnetic flux elements by a field characterized by spatio-temporal correlations mimicking granulation and supergranulation scales observed on the photosphere. At this stage we can only take into account the effects of diffusion and impingement, from the appearance of magnetic flux concentrations to their dissolution. The inclusion of such a model into full-Sun simulations, also including large scale effects such as differential rotation and meridional flows, might be useful not only for studying variability and the solar cycle, but also for the investigation of Sun-like stars luminosity and radial velocity fluctuations, observed for example by Kepler mission, in order to investigate the impact of stellar magnetic activity on the detection of exoplanets. Title: Spectropolarimetric analysis of the solar Active Region NOAA11005 by inversion techniques: preliminary results. Authors: Giannattasio, F.; Del Moro, D.; Viticchiè, B.; Stangalini, M.; Berrilli, F. Bibcode: 2012MSAIS..19...97G Altcode: We present the preliminary results of spectropolarimetric observations and analysis of a disk-center region containing a pore. The dataset was acquired on 2008/10/15 by the SOT spectropolarimeter onboard the Solar-B (Hinode) mission. It consists of high spatial and spectral (2.15 pm) resolution full Stokes imaging scans in the iron doublet at 630 nm, in Fast Map Mode (0.3×0.32 arcsec2 pixel scale), with 0.1% polarimetric accuracy. The analysis of a 60×60 pxls2 area around the pore was performed by inversion techniques using the SIR code. We gave in input an initial atmospheric model with a single magnetic component, but accounting for stray light contamination. The code is capable of retrieving the full Stokes syntetized profiles and the inverted atmospheric parameters, like plasma temperature, magnetic field vector etc., for each depth and resolution element. We show and comment the magnetic field reconstruction maps (field strengths and inclinations) as inferred from SIR inversion procedure, comparing to what emerges from the linear polarization maps. Title: Properties of G-band Bright Points derived from IBIS observations Authors: Criscuoli, S.; Del Moro, D.; Giorgi, F.; Romano, P.; Berrilli, F.; Ermolli, I.; Viticchié, B.; Zuccarello, F. Bibcode: 2012MSAIS..19...93C Altcode: 2010arXiv1011.4890C We have investigated properties of photospheric Bright Points (BPs) observed in an Active Region during its decay phase and in a quiet Sun region. We have analyzed two sets of photospheric observations taken with IBIS (Interferometric Bidimensioal Spectrometer) at the NSO Dunn Solar Telescope. The first set consists of spectral data acquired in the Fe I 709.0 nm and Ca I 854.2 nm lines and simultaneous broad-band and of G-band observations. The second set consists of spectro-polarimetric observations in the Fe I 630.15 nm - 630.25 nm doublet and simultaneous white light and G-band observations.

The relation between BP filling factor and RMS image contrast indicates that, on average, BPs cover up to 3% of the solar surface outside Active Regions. The relation between area and intensity values of the features identified on both data sets suggests that they are composed of aggregations of magnetic flux elements. The horizontal velocity values are as high as 2 km/s, thus supporting the scenario of BPs motion contributing to the coronal heating. Title: Magnetic and velocity fields of a solar pore Authors: Sobotka, M.; Del Moro, D.; Jurčák, J.; Berrilli, F. Bibcode: 2012A&A...537A..85S Altcode: Context. Solar pores are intermediate-size magnetic flux features that emerge at the surface of the Sun. The absence of a filamentary penumbra indicates that there is a relatively simple magnetic structure with a prevailing vertical magnetic field.
Aims: Relations between the magnetic field components, line-of-sight velocities, and horizontal motions in and around a large pore (Deff = 8''.5) are analysed to provide observational constraints on theoretical models and numerical simulations.
Methods: Spectropolarimetric observations in Fe I 617.3 nm of the pore NOAA 11005 with the IBIS spectrometer attached to the Dunn Solar Telescope are inverted into series of maps of thermal, magnetic, and velocity parameters using the SIR code. Horizontal velocities are obtained from series of white-light images by means of local correlation tracking.
Results: The magnetic field B extends from the visible pore border of more than 3''.5 and has a radial structure in a form of spines that are co-spatial with dark intergranular lanes. The horizontal component Bhor is more extended than the vertical component Bz. The temperature linearly decreases with increasing Bz, by about - 300 K kG-1 in the photosphere and - 800 K kG-1 in the umbra. The temperature contrast of granulation increases with increasing magnetic field strength and is then suppressed for Bz > 1200 G. Granular upflows dominate in regions with Bz < 600-700 G. Line-of-sight velocities are lower in stronger fields, except for fast isolated downflows at the pore's border. The velocity signature of granulation is suppressed completely for Bhor > 1000 G. Horizontal motions of granules start to be damped for Bz > 500 G and recurrently exploding granules appear only in magnetic fields comparable to or weaker than the equipartition field strength 400 G. Title: The intensity effect in magneto-optical filters Authors: Oliviero, M.; Severino, G.; Berrilli, F.; Moretti, P. F.; Jefferies, S. M. Bibcode: 2011SPIE.8148E..0VO Altcode: 2011SPIE.8148E..27O We used a laser system for determining the bandpasses of the two vapour cells, the Magneto-Optical Filter (MOF) and the Wing Selector (WS), which are the core of solar narrow-band filters based on the MOF technology. A new result, which we called the Intensity Effect, was found: the MOF and WS bandpasses depend not only on the temperature at which the cell is heated and the external magnetic field in which the cell is embedded, but also on the radiation intensity entering the cell. A theoretical interpretation of the Intensity Effect is proposed in terms of the kinetic equilibrium of the potassium atomic populations inside the vapour cell. We need to take the Intensity Effect into account for setting-up MOF based instruments for solar and stellar observations as well as for modelling the MOF and WS spectral transmissions. Title: DIMMI-2h a MOF-based instrument for Solar Satellite ADAHELI Authors: Stangalini, M.; Moretti, P. F.; Berrilli, F.; Del Moro, D.; Jefferies, S. M.; Severino, G.; Oliviero, M. Bibcode: 2011SPIE.8148E..0US Altcode: 2011SPIE.8148E..26S The Doppler-Intensity-Magnetograms with a Magneto-optical filter Instrument at two heights (DIMMI-2h) is a double channel imager using Magneto Optical Filters (MOF) in the potassium 770 nm and sodium 589 nm lines. The instrument will provide simultaneous dopplergrams (velocity fields), continuum intensity and longitudinal magnetic flux images at two heights in the solar atmosphere corresponding to low and high photosphere. Dimmi- 2h is the possible piggy-back payload on ADAHELI satellite. The spatial resolution (approximately 4 arcsec) and the high temporal cadence (15 s) will permit to investigate low and medium oscillating modes (from 0 to below 1000) up to approximately 32 mHz in the frequency spectrum. The acquisition of long-term simultaneous velocity, intensity and magnetic information up to these high frequencies will permit also the study of the propagation and excitation of the waves with a frequency resolution never obtained before. Title: MHD wave transmission in the Sun's atmosphere Authors: Stangalini, M.; Del Moro, D.; Berrilli, F.; Jefferies, S. M. Bibcode: 2011A&A...534A..65S Altcode: 2011arXiv1108.4576S Magnetohydrodynamics (MHD) wave propagation inside the Sun's atmosphere is closely related to the magnetic field topology. For example, magnetic fields are able to lower the cutoff frequency for acoustic waves, thus allowing the propagation of waves that would otherwise be trapped below the photosphere into the upper atmosphere. In addition, MHD waves can be either transmitted or converted into other forms of waves at altitudes where the sound speed equals the Alfvén speed. We take advantage of the large field-of-view provided by the IBIS experiment to study the wave propagation at two heights in the solar atmosphere, which is probed using the photospheric Fe 617.3 nm spectral line and the chromospheric Ca 854.2 nm spectral line, and its relationship to the local magnetic field. Among other things, we find substantial leakage of waves with five-minute periods in the chromosphere at the edges of a pore and in the diffuse magnetic field surrounding it. By using spectropolarimetric inversions of Hinode SOT/SP data, we also find a relationship between the photospheric power spectrum and the magnetic field inclination angle. In particular, we identify well-defined transmission peaks around 25° for five-minute waves and around 15° for three-minute waves. We propose a very simple model based on wave transmission theory to explain this behavior. Finally, our analysis of both the power spectra and chromospheric amplification spectra suggests the presence of longitudinal acoustic waves along the magnetic field lines. Title: The Fabry-Perot interferometer prototype for the ADAHELI solar small mission Authors: Berrilli, Francesco; Cocciolo, Martina; Giovannelli, Luca; Del Moro, Dario; Giannattasio, Fabio; Piazzesi, Roberto; Stangalini, Marco; Egidi, Alberto; Cavallini, Fabio; Greco, Vincenzo; Selci, Stefano Bibcode: 2011SPIE.8148E..07B Altcode: 2011SPIE.8148E...6B ADAHELI ADvanced Astronomy for HELIophysics is a solar satellite designed to investigate the fast dynamics of the solar photosphere and chromosphere performing visible and NIR broad-band and monochromatic observations of selected atomic lines. ADAHELI is an Italian Space Agency (ASI) project, approved for a feasibility study within the ASI Small Missions call. ISODY Interferometer for SOlar DYnamics is a Gregorian telescope and its focal plane suite (FPS). The FPS is composed of a high-resolution fast acquisition system, based upon a tandem of Fabry-Pérot interferometers operating in the visible and NIR regions on selected solar atmospheric lines, a broad band channel, and a correlation tracker used as image stabilization system. In this contribution we describe the Fabry-Pérot étalon prototype, based on the capacitance-stabilised concept, realized in our laboratory to perform preliminary mechanical and optical tests with a view to a future Fabry-Pérot étalon prototype for space application. Title: A comparative test of different compression methods applied to solar images Authors: Del Moro, Dario; Pietropaolo, Ermanno; Giannattasio, Fabio; Berrilli, Francesco Bibcode: 2011SPIE.8136E..0JD Altcode: 2011SPIE.8136E..16D In this work we conduct a comparative study on different data compression methods applied to high resolution images of the solar surface acquired at the Solar Dunn Telescope in Sacramento Peak with the IBIS (Interferometric Bidimensional Spectrometer) instrument. Our aim is to perform an estimation of the quality, efficiency and workload of the considered computing techniques both in the so-called lossless modality, where in the reconstruction phase there is no loss of information, and in lossy mode, where it should be possible to reach a high compression ratio at the expense of image information. In the latter case we quantify the quality with image analysis conventional methods and more specifically with the reconstruction of physical parameters through standard procedures used in this kind of observations. The considered methods constitute the most frequently adopted image compression procedures in a variety of fields of application; they exploit in different ways the properties of the Discrete Wavelet Transforms often coupled with standard entropy coders or similar coding procedures applied to the different bit planes in order to allow a progressive handling of the original image. In the lossless approach we found that all methods give a compression ratio around 2. For a lossy compression we reached a compression ratio of 8 (equivalent to a 2 bit per pixel) without any perceptual difference between original and reconstructed images, but with effects on the photometric accuracy. We also tested the performance of 3-D lossy methods for the compression of data-cubes. Maintaining the same data degradation level, those methods allows us to gain a 2x in the compression ratio over the 2-D methods. Title: IBIS 2D Spectropolarimetry: Analysis of G-band Bright Points Authors: Viticchiè, B.; Del Moro, D.; Berrilli, F.; Rubio, L. B.; Tritschler, A. Bibcode: 2011ASPC..437...75V Altcode: We present the results derived from the analysis of the first spectropolarimetric (SP) data obtained through the Interferometric BIdimensional Spectrometer (IBIS) at the Dunn Solar Telescope (NSO). The analysis is focused on 103 G small scale (∼100 km) magnetic field concentrations observed, in a quiet Sun region, as bright points in G-band filtergrams. The combination of high spatial and temporal resolution of both SP and G-band datasets allowed us to analyze in detail the magnetic properties of bright points over different spatial scales (from ∼eq. 0.4" up to 2"- 3") and temporal scales (from 10 min up to > 60 min) and, beside this, to focus on the dependence of significant physical quantities (i.e., magnetic field strength and filling factor derived from Stokes profile inversion) in relation with such evolutions.

We present two main results of our analysis: i) evolution of bright points over small spatial scales and short time intervals (by considering the coalescence of small and faint bright points into a single high brightness one); ii) magnetic properties of bright points over large spatial scales (by examining a small network patch). Our study indicates an interesting correlation between G-band brightness and magnetic filling factor fluctuations. On the contrary, we have not observed any correlation between G-band brightness and magnetic field strength. Such a result can help us to conclude on the possible fine structuring of kG concentrations in the solar photosphere which produce brightness enhancement in G-band filtergrams. Title: Evolution of Small-scale Magnetic Features Streaming-out from a Pore Authors: Criscuoli, S.; Del Moro, D.; Romano, P.; Berrilli, F.; Ermolli, I. : Giorgi, F.; Vitichhié, B.; Zuccarello, F. Bibcode: 2011ASPC..437..493C Altcode: We present results from observations of Moving Magnetic Features (MMFs) of different types observed on region NOAA 11005. The analyses is based on spectro-polarimetric data obtained with the Interferometric Bidimensional Spectrometer (IBIS) at various spectral ranges. We present new evidences of bipolar MMFs observed to stream out from pores and show the temporal evolution of magnetic, dynamic and morphological properties of these features. Title: MISMA Interpretation of Stokes V Asymmetries Measured by HINODE in Internetwork and Network Regions Authors: Viticchiè, B.; Sánchez Almeida, J.; Del Moro, D.; Berrilli, F. Bibcode: 2011ASPC..437..127V Altcode: Stokes profiles observed in the quiet photosphere by HINODE SOT/SP present very complex shapes. These are indicative of unresolved magnetic structures and/or gradients along the line of sight in HINODE's pixels which have linear dimension of ∼0.15". We present the first interpretation of the Stokes profile asymmetries measured in the 630 nm Fe I lines by SOT/SP in both quiet Sun internetwork (IN) and network. The inversion is carried out under the hypothesis of MIcro-Structured Magnetized Atmosphere (MISMA) which can account for sub-pixel structuring of magnetic fields. The MISMA code is able to reproduce the observed asymmetries in a very satisfactory way. Moreover, 25% of inverted profiles present asymmetries that are interpreted as produced by regions in which mixed polarities are present. kG field strengths are found in both network and internetwork regions. In the internetwork both kG fields and hG fields are found. Our analysis constrains the magnetic field of only 4.5% of the analyzed photosphere. The rest of the plasma can be thought to be filled by weak fields not contributing to the detected polarization signals. Title: Interpretation of HINODE SOT/SP asymmetric Stokes profiles observed in the quiet Sun network and internetwork Authors: Viticchié, B.; Sánchez Almeida, J.; Del Moro, D.; Berrilli, F. Bibcode: 2011A&A...526A..60V Altcode: 2010arXiv1009.6065V Stokes profiles emerging from the magnetized solar photosphere and observed by SOT/SP aboard the HINODE satellite exhibit a variety of complex shapes. These are indicative of unresolved magnetic structures that have been overlooked in the inversion analyses performed so far. Here we present the first interpretation of the Stokes profile asymmetries measured in the ion{Fe}{i} 630 nm lines by SOT/SP, in both quiet Sun internetwork (IN) and network regions. The inversion is carried out based on the hypothesis of MIcro-Structured Magnetized Atmosphere (MISMA), where the unresolved structure is assumed to be optically thin. We analyze a 29.52 arcsec × 31.70 arcsec subfield carefully selected to be representative of the properties of a 302 arcsec × 162 arcsec quiet Sun field-of-view (FOV) at the disk center. The inversion code is able to reproduce the observed asymmetries in a very satisfactory way, including 35% of the inverted profiles with large asymmetries. The inversion code interprets 25% of inverted profiles as emerging from pixels in which both positive and negative polarities coexist. These pixels are located in either frontiers between opposite polarity patches or very quiet regions. The kG field strengths are found at the base of the photosphere in both network and IN regions; in the case of the latter, both kG fields and hG fields are admixed. When considering the magnetic properties of the mid photosphere, most kG fields do not exist, and the statistics is dominated by hG fields. According to the magnetic filling factors derived from the inversion, we constrain the magnetic field of only 4.5% of the analyzed photosphere (and this percentage reduces to 1.3% when considering all pixels, including those with low polarization that have not been analyzed). The properties of the rest of the plasma imply that weak fields do not contribute to the detected polarization signals. The average flux densities derived in the full subfield and IN regions are higher than those derived from the same dataset by Milne-Eddington (ME) inversion. We detect large asymmetries in the HINODE SOT/SP polarization profiles. These are not negligible in quiet Sun data. The MISMA inversion code reproduces them in a satisfactory way, and provides a statistical description of the magnetized IN and network which partly differs and complements the results obtained so far. The importance of having a complete interpretation of the line profile shapes is therefore clearly evident. Title: The Void Probability Distribution Observed in High-Resolution Hinode/SOT and SDO Magnetograms Authors: Berrilli, F.; Del Moro, D.; Giannattasio, F.; Scardigli, S.; Viticchie, B. Bibcode: 2010AGUFMSH11A1610B Altcode: A new searching algorithm to find voids in high resolution magnetograms is described. This algorithm permits the investigation of spatially intermittent nature of magnetic field emerging when solar surface is observed at high spatial resolution. Actually, at these small scales, the connected patterns, forming magnetic network, show aligned or clustered magnetic features producing a highly branched and fractal pattern embodying magnetic elements. High resolution Hinode/SOT and SDO magnetograms confirmed the presence of multiscale underdense (voids) magnetic regions. Preliminary Void Probability Distribution (VPD), measured in such high-resolution magnetograms, are presented and briefly discussed. Title: Imaging Spectropolarimetry with IBIS. II. On the Fine Structure of G-band Bright Features Authors: Viticchié, B.; Del Moro, D.; Criscuoli, S.; Berrilli, F. Bibcode: 2010ApJ...723..787V Altcode: 2010arXiv1009.0721V We present new results from first observations of the quiet solar photosphere performed through the Interferometric BIdimensional Spectrometer (IBIS) in spectropolarimetric mode. IBIS allowed us to measure the four Stokes parameters in the Fe I 630.15 nm and Fe I 630.25 nm lines with high spatial and spectral resolutions for 53 minutes; the polarimetric sensitivity achieved by the instrument is 3 × 10-3 the continuum intensity level. We focus on the correlation which emerges between the G-band bright feature brightness and magnetic filling factor of ~103 G (kG) fields derived by inverting the Stokes I and V profiles. In more detail, we present the correlation first in a pixel-by-pixel study of a sime3'' wide bright feature (a small network patch) and then we show that such a result can be extended to all the bright features found in the data set at any instant of the time sequence. The higher the kilo-Gauss filling factor associated to a feature, the higher the brightness of the feature itself. Filling factors up to sime35% are obtained for the brightest features. Considering the values of the filling factors derived from the inversion analysis of spectropolarimetric data and the brightness variation observed in the G-band data we put forward an upper limit for the smallest scale over which magnetic flux concentrations in intergranular lanes produce a G-band brightness enhancement (sime0farcs1). Moreover, the brightness saturation observed for feature sizes comparable to the resolution of the observations is compatible with the large G-band bright features being clusters of sub-arcsecond bright points. This conclusion deserves to be confirmed by forthcoming spectropolarimetric observations at higher spatial resolution. Title: Modeling the solar irradiance background via numerical simulation Authors: Viticchié, B.; Vantaggiato, M.; Berrilli, F.; Del Moro, D.; Penza, V.; Pietropaolo, E.; Rast, M. Bibcode: 2010Ap&SS.328...39V Altcode: 2010Ap&SS.tmp...58V Various small scale photospheric processes are responsible for spatial and temporal variations of solar emergent intensity. The contribution to total irradiance fluctuations of such small scale features is the solar irradiance background. Here we examine the statistical properties of irradiance background computed via a n-body numerical scheme mimicking photospheric space-time correlations and calibrated by means of IBIS/DST spectro-polarimetric data. Such computed properties are compared with experimental results derived from the analysis of a VIRGO/SPM data. A future application of the model here presented could be the interpretation of stellar irradiance power spectra observed by new missions such as Kepler. Title: Multiple field-of-view MCAO for a Large Solar Telescope: LOST simulations Authors: Stangalini, Marco; Berrilli, Francesco; Del Moro, Dario; Piazzesi, Roberto Bibcode: 2010SPIE.7736E..4HS Altcode: 2010SPIE.7736E.151S; 2010arXiv1008.0555S In the framework of a 4m class Solar Telescope we studied the performance of the MCAO using the LOST simulation package. In particular, in this work we focus on two different methods to reduce the time delay error which is particularly critical in solar adaptive optics: a) the optimization of the wavefront reconstruction by reordering the modal base on the basis of the Mutual Information and b) the possibility of forecasting the wavefront correction through different approaches. We evaluate these techniques underlining pros and cons of their usage in different control conditions by analyzing the results of the simulations and make some preliminary tests on real data. Title: The heat stop for the 4-m European Solar Telescope EST Authors: Berrilli, F.; Egidi, A.; Del Moro, D.; Manni, F.; Cocciolo, M.; Scotto, A.; Volkmer, R.; Bettonvil, F. C. M.; Collados Vera, M.; Cavaller Marquez, L.; Sanchez Capuchino, J. Bibcode: 2010SPIE.7733E..2ZB Altcode: 2010SPIE.7733E..92B A study is presented for the realization of the heat stop for the 4-m European Solar Telescope EST, whose feasibility study will be completed in 2011. EST is an on-axis Gregorian telescope, equipped with a four-meter diameter primary mirror and primary focal length of about six meters. The heat stop, positioned at the primary focus, must be able to remove a heat load of 13 kW, while maintaining its surfaces very close to room temperature, to avoid the onset of seeing. In order to remove the heat, three configurations have been taken into consideration: 1) a flat 45° inclined heat rejecter, 2) a 45° conical heat rejecter and 3) a heat trap (made of a conical heat rejecter and a cylindrical heat absorber). All devices include an air removal system to avoid the formation of thermal plumes. Title: The telescope and the double Fabry-Pérot interferometer for the ADAHELI solar space mission Authors: Greco, V.; Cavallini, F.; Berrilli, F. Bibcode: 2010SPIE.7731E..42G Altcode: 2010SPIE.7731E.131G ADvanced Astronomy for HELIophysics (ADAHELI) is a Small Mission to study the structure and fast dynamics of the low solar atmosphere, performing Visible-NIR monochromatic and broad-band observations. The mission will achieve millimeter full disk observations as well. The ADAHELI Team has succesfully completed, in December 2008, the Phase A study awarded by the Italian Space Agency (ASI). The Interferometer for SOlar Dynamics (ISODY), on board the ADAHELI satellite, comprises a Gregorian telescope and its focal plane suite. The advanced design focal plane suite uses fast CMOS cameras for investigating photospheric and chromospheric fast dynamics and structure. ISODY is equipped with a pioneering focal plane suite composed of a spectral channel, based upon a tandem of Fabry-Perot interferometers operating in the visible-NIR spectral region, a broad band channel for high resolution imaging, and a correlation tracker used as an image stabilization system. ADAHELI's mission profile has been tailored to limit the spacecraft's radial velocity in the Sunward direction, to not exceed +/-4 km/s, during 95% of the yearly orbit, to allow a continuous use of the on-board interferometer. Title: EST Telescope: primary mirror, support, and cooling system Authors: Volkmer, R.; Manni, F.; Giannuzzi, M.; Scotto, A.; Cavaller, L.; Scheiffelen, T.; Bettonvil, F.; Berrilli, F. Bibcode: 2010SPIE.7739E..1OV Altcode: 2010SPIE.7739E..52V The solar telescope EST is currently in the conceptual design phase. It is planned to be build on the Canary Islands until end of the decade. It is specialized on polarimetric observations and will provide high spatial and spectral observations of the different solar atmospheric layers. The diameter of the primary mirror blank is 4.2m. Different types of mirror shapes were investigated with respect to thermal and mechanical characteristics. To remove the absorbed heat an air cooling system from the back side will be applied. Additional an air flushing system will remove remaining warm air from the front side. A major problem of a large open telescope will be the wind load. Results of the investigations will be shown. To achieve optimal optical performance an active support system is planned. The primary mirror cell needs to be stiff enough to support the primary mirror without deformation at strong wind in case of the open telescope option, but sufficient room for the active support system and cooling system below the backside of the mirror is also required. Preliminary designs and analysis results will be presented. Title: Future instrumentation for solar physics: a double channel MOF imager on board ASI Space Mission ADAHELI Authors: Moretti, P. F.; Berrilli, F.; Bigazzi, A.; Jefferies, S. M.; Murphy, N.; Roselli, L.; di Mauro, M. P. Bibcode: 2010Ap&SS.328..313M Altcode: 2010Ap&SS.tmp...12M A Magneto-Optical Filter-based system has been proposed as an optional payload for ASI’s low-budget Solar Mission ADAHELI, which has completed its Phase A feasibility study. The instrument is capable of providing simultaneous Dopplergrams, intensity and magnetic solar full-disk maps using the potassium 770 nm and sodium 589 nm solar Fraunhofer lines. The instrument is a version, re-designed for a space environment, of the one which has run an observing campaign at the South Pole in 2008 with unprecedented performance. The MOF-based system we present here is a low-cost, low-weight instrument, thus particularly fit to space applications, capable of providing stability and sensitivity of signals on long-term observations. The instrument will explore regions of the oscillation spectrum not available to other missions’ instruments. Title: The ADAHELI solar mission: Investigating the structure of Sun's lower atmosphere Authors: Berrilli, F.; Bigazzi, A.; Roselli, L.; Sabatini, P.; Velli, M.; Alimenti, F.; Cavallini, F.; Greco, V.; Moretti, P. F.; Orsini, S.; Romoli, M.; White, S. M.; ADAHELI Team; Ascani, L.; Carbone, V.; Curti, F.; Consolini, G.; Di Mauro, M. P.; Del Moro, D.; Egidi, A.; Ermolli, I.; Giordano, S.; Pastena, M.; Pulcino, V.; Pietropaolo, E.; Romano, P.; Ventura, P.; Cauzzi, G.; Valdettaro, L.; Zuccarello, F.; ADAHELI Team Bibcode: 2010AdSpR..45.1191B Altcode: 2010AdSpR..45.1191A ADAHELI (ADvanced Astronomy for HELIophysics) is a small-class (500 kg) low-budget (50 MEuro) satellite mission for the study of the solar photosphere and the chromosphere and for monitoring solar flare emission. ADAHELI's design has completed its Phase-A feasibility study in December 2008, in the framework of ASI's (Agenzia Spaziale Italiana) 2007 "Small Missions" Program (calling for two missions at 50 MEeuros each, plus the launch budget). ADAHELI's main purpose is to explore Sun's lower atmosphere in the near-infrared, a region so far unexplored by solar observations from space. ADAHELI will carry out observations of the solar photosphere and of the chromosphere at high-temporal rate and high spatial and spectral resolutions. ADAHELI will contribute to the understanding of Space Weather through the study of particle acceleration during flares. A radiometer operating in the millimeter radio band will continuously monitor the solar disk, throughout the spacecraft's life time. ADAHELI's baseline instruments are a 50-cm high-resolution telescope operating in the visible and the near-infrared, and a lightweight full-disk radiometer operating at millimeter wavelengths (90 GHz). The core of the telescope's focal plane suite is the spectral imager based on two Fabry-Perot interferometers, flying for the first time on a solar mission. The instrument will return fast-cadence, full bi-dimensional spectral images at high-resolution, thus improving on current slit-scan, mono-dimensional architectures. Moreover, the possibility of working in polarized light will enable full 3D magnetic field reconstruction on the photosphere and the chromosphere. An optional instrumental package is also being proposed to further extend ADAHELI's scope: a full-disk telescope for helioseismology based on a double Magneto-Optical Filter, a Neutral Particle Analyzer for magnetospheric research, an Extreme Ultraviolet imaging and spectro-radiometry instrument. These options fall outside the prescribed budget. ADAHELI, flying a Sun-Synchronous orbit at 800 km, will perform continuous, long-duration (4-h), daily acquisitions, with the possibility of extending them up to 24 h. ADAHELI's operating life is two years, plus one extension year. Launch would be nominally planned for 2014. Title: MCAO for the European Solar Telescope: first results. Authors: Stangalini, M.; Piazzesi, R.; Del Moro, D.; Berrilli, F.; Egidi, A. Bibcode: 2010MSAIS..14..198S Altcode: 2009arXiv0912.2606S We analize the efficiency of wavefront reconstruction in the MultiConjugate Adaptive Optics system for the European Solar Telescope (EST). We present preliminary results derived from numerical simulations. We study a 4 meter class telescope with multiple deformable mirrors conjugated at variable heights. Along with common issues, difficulties peculiar to the solar case have to be considered, such as the low contrast and extended nature of the natural guide features. Our findings identify basic requirements for the EST Adaptive Optics system and show some of its capabilities. Title: Coupling photosphere and chromosphere through plasma waves. Authors: Stangalini, M.; Berrilli, F.; Del Moro, D.; Egidi, A.; Giordano, S.; Moretti, P. F.; Viticchiè, B. Bibcode: 2010MmSAI..81..806S Altcode: The new capabilities of fast bidimensional spectropolarimetric scanning, allowed by recent instrumental development, provide a new insight into the study of chromospheric active regions. We present results from the analysis of datasets acquired with Interferometric BIdimensional Spectrometer operating at the Dunn Solar Telescope in spectrometric and spectropolarimetric mode. The high spatial and temporal resolution allows us to study oscillations and MHD wave propagation between photosphere and chromosphere. In particular we focused on the coupling between photospheric magnetic field and wave transmission. Among other findings, we observe a shift of the cross-correlation spectrum, above those photospheric regions where the magnetic field vector is strongly inclined with respect to the line of sight. Such a result could offer a new perspective for the understanding of plasma wave reprocessing. Title: Imaging spectropolarimetry with IBIS: evolution of a magnetic feature. Authors: Del Moro, D.; Stangalini, M.; Viticchiè, B.; Vantaggiato, M.; Giannattasio, F.; Piazzesi, R.; Berrilli, F.; Egidi, A.; IBIS Team Bibcode: 2010MSAIS..14..180D Altcode: We present the results from observations of the solar atmosphere acquired at the Dunn Solar Telescope with the Interferometric Bidimensional Spectrometer (IBIS). Full Stokes profiles in the FeI 617.3 line and Stokes I in the CaII 854.2 were acquired with high spatial and spectral resolutions for more than one hour allowing us to study the evolution of a magnetic feature associated to AR11005. Here we search for possible correlations between photospheric and chromospheric events examining the magnetic flux density evolution and waves propagation in the solar atmosphere. Title: The Intensity Profile of the Solar Supergranulation Authors: Goldbaum, Nathan; Rast, Mark P.; Ermolli, Ilaria; Sands, J. Summer; Berrilli, Francesco Bibcode: 2009ApJ...707...67G Altcode: 2009arXiv0909.3310G We have measured the average radial (cell center to network boundary) profile of the continuum intensity contrast associated with supergranular flows using data from the Precision Solar Photometric Telescope at the Mauna Loa Solar Observatory. After removing the contribution of the network flux elements by the application of masks based on Ca II K intensity and averaging over more than 105 supergranular cells, we find a ~0.1% decrease in red and blue continuum intensity from the supergranular cell centers outward, corresponding to a ~1.0 K decrease in brightness temperature across the cells. The radial intensity profile may be caused either by the thermal signal associated with the supergranular flows or a variation in the packing density of unresolved magnetic flux elements. These are not unambiguously distinguished by the observations, and we raise the possibility that the network magnetic fields play an active role in supergranular scale selection by enhancing the radiative cooling of the deep photosphere at the cell boundaries. Title: Spectropolarimetry with IBIS at NSO/DST: Evolution of Bright Points in the Quiet Sun Authors: Stangalini, M.; Viticchiè, B.; Del Moro, D.; Piazzesi, R.; Berrilli, F. Bibcode: 2009AGUFMSH51A1269S Altcode: We present the results from the SIR inversion of spectropolarimetric data acquired with the IBIS (Interferometric BIdimensional Spectrometer) instrument at the NSO Dunn Solar Telescope, Sacramento Peak (NM, USA). The inversion analysis is performed on Stokes I and V profiles measured in the two FeI visible lines at 630 nm over a (~ 40 x 40 Mm) quiet Sun portion, for a time interval of 53 minutes. The noise level for Stokes V profiles is 0.003 the continuum intensity. The high spatial resolution of the G-band images combined with the inversion results helps to interpret the physical properties of G-band bright points, i.e., their field strength and magnetic filling factor. Moreover, the time span of the observation allows to investigate the variation of such physical quantities with time. More in detail, we focus on the analysis of three distinct processes, namely the coalescence, fragmentation, and cancellation of G-band bright points. Title: Analysis of Supergranulation Pattern: the Void Probability Function of Solar Magnetograms Authors: Berrilli, F.; Giordano, S.; Del Moro, D. Bibcode: 2009AGUFMSH51A1263B Altcode: The appearance of large scale magnetic fields on the non-active solar surface is dominated by the so-called magnetic network. In full disk images, the reticulated pattern of such a network outlines the boundaries of the supergranular cells and, presumably, it results from the organization of tiny magnetic elements caused by horizontal convective flows of photospheric plasma. The magnetic network, when observed at high spatial resolution, reveals its spatially intermittent nature. As a matter of fact, the reticulated pattern is substituted by a collection of, more or less, aligned or clustered magnetic features producing a highly branched and fractal pattern embodying isolated magnetic elements. Recent spectropolarimetric observations, from space and ground-based telescopes, revealed the presence in solar magnetograms of multiscale underdense magnetic regions, commonly called voids, which may be considered a relevant signature of the processes occurring on the surface of our star. A void searching algorithm is used to study the statistical properties of such voids as observed in MDI and HINODE magnetograms. A clear discrepancy is observed between distributions of voids diameters for solar magnetograms and for a pseudo-random distribution having comparable particle densities. Title: Imaging Spectropolarimetry with IBIS: Evolution of Bright Points in the Quiet Sun Authors: Viticchié, B.; Del Moro, D.; Berrilli, F.; Bellot Rubio, L.; Tritschler, A. Bibcode: 2009ApJ...700L.145V Altcode: 2009arXiv0906.2663V We present the results from first spectropolarimetric observations of the solar photosphere acquired at the Dunn Solar Telescope with the Interferometric Bidimensional Spectrometer. Full Stokes profiles were measured in the Fe I 630.15 nm and Fe I 630.25 nm lines with high spatial and spectral resolutions for 53 minutes, with a Stokes V noise of 3 × 10-3 the continuum intensity level. The data set allows us to study the evolution of several magnetic features associated with G-band bright points (BPs) in the quiet Sun. Here we focus on the analysis of three distinct processes, namely the coalescence, fragmentation, and cancellation of G-band BPs. Our analysis is based on an SIR inversion of the Stokes I and V profiles of both Fe I lines. The high spatial resolution of the G-band images combined with the inversion results helps to interpret the undergoing physical processes. The appearance (dissolution) of high-contrast G-band BPs is found to be related to the local increase (decrease) of the magnetic filling factor, without appreciable changes in the field strength. The cancellation of opposite-polarity BPs can be the signature of either magnetic reconnection or the emergence/submergence of magnetic loops. Title: Mn I Lines with Hyperfine Structure Synthesized in Realistic Quiet-Sun Atmospheres Authors: Viticchié, B.; Sánchez Almeida, J.; Landi Degl'Innocenti, E.; Berrilli, F. Bibcode: 2009ASPC..405..319V Altcode: We present the first synthesis of Mn I lines in realistic multi-component magnetized quiet Sun atmospheres, including variation of magnetic field strength, magnetic field direction, plasma velocity, and coupling between magnetic field and thermodynamics. All synthesized Mn I lines weaken for strong magnetic fields. A detailed analysis of the Mn I λ5538 line shows that the Weak Field Approximation (WFA) breaks down at 400~G, and that kG magnetic fields produce Stokes V profiles with amplitudes up to two orders of magnitude smaller than those predicted by the WFA. Consequently, the polarization emerging from an atmosphere in which weak (hG) and strong (kG) fields coexist is biased towards the hG field polarization. When including velocity gradients, profiles showing important asymmetries are produced, and these profiles cannot be obtained using single-component magnetized model atmospheres. We synthesize Mn I lines presenting very different hyperfine structure (HFS) patterns, and all of them reproduce the observed Stokes I profiles in a really satisfactory way. Title: Observation of bipolar moving magnetic features streaming out from a naked spot Authors: Zuccarello, F.; Romano, P.; Guglielmino, S. L.; Centrone, M.; Criscuoli, S.; Ermolli, I.; Berrilli, F.; Del Moro, D. Bibcode: 2009A&A...500L...5Z Altcode: Context: Mechanisms responsible for active-region formation, evolution, and decay have been investigated by many authors and several common features have been identified. In particular, a key element in the dispersal of the magnetic field seems to be the presence of magnetic elements, called moving magnetic features (MMFs).
Aims: We analyze the short-lived sunspot group NOAA 10977, which appeared on the solar disk between 2 and 8 December 2007, to study the details of its emergence and decay phases.
Methods: We performed a multi wavelength analysis of the region using images at visible (G band and Hα) and near-IR (Ca II) wavelengths acquired by both the IBIS instrument and SOT/HINODE, EUV images (17.1 nm) acquired by TRACE, and MDI and SOT magnetograms.
Results: The observed region exhibits some peculiarities. During the emergence phase the formation of the f-pore was initially observed, while the p-polarity later formed a naked spot, i.e., a sunspot without a penumbra. We measured a moat flow around this spot, and observed some MMFs streaming out from it during the decay phase. The characteristics of these MMFs allowed us to classify them as type I (U-shaped) MMFs. They were also cospatial with sites of increased brightness both in the photosphere and the chromosphere.
Conclusions: The presence of bipolar MMFs in a naked spot indicates that current interpretation of bipolar MMFs, as extensions of the penumbral filaments beyond the sunspot outer boundaries, should be revised, to take into account this observational evidence. We believe that our results provide new insights into improving models of sunspot evolution. Title: Wavefront sensing for Themis: a case study for next generation solar telescopes like EST . Authors: Stangalini, M.; Del Moro, D.; Berrilli, F. Bibcode: 2009MmSAI..80..293S Altcode: Wavefront sensing is one of the most challenging problem in solar Adaptive Optics (AO) due to the presence of extended and low contrast AO-targets on the solar scene. We show preliminary results of wavefront modal phase estimation on THEMIS Solar Telescope data, using two approaches: Zernike (ZE) and Karhunen-Loeve (K-L) polynomial expansions. We have analyzed Shack-Hartmann (SH) dataset, and the wavefront phases were reconstructed. A study of pros and cons of the two different modal expansions has been carried out. These results could be particularly helpful in developing and studying design and performances for next generation solar telescopes based upon annular pupils. Title: The ADAHELI (ADvanced Astronomy for HELIophysics) solar mission Authors: Berrilli, F.; Velli, M.; Roselli, L.; Bigazzi, A.; ADAHELI Team Bibcode: 2009MmSAI..80..251B Altcode: The ADAHELI (ADvanced Astronomy for HELIOphysics) small mission is an Italian project for the investigation of solar activity and dynamics proposed in the framework of ASI Italian Space Agency Small Missions Program call. It is devoted to the study of photospheric and chromospheric structure and dynamics. The scientific payload consists of ISODY, a telescope with a focal plane suite operating in the visible and near infrared, and MIOS, a 90GHz radiometer. The telescope is equipped with a spectro-polarimetric imager, based on Fabry-Perot interferometers, a broad band imager, and an image stabilization system. The 90GHz radiometer is a full-disk instrument exploiting an antenna with an angular aperture of about ±25 arcmin. Proposals for optional instruments are under evaluation: DIMMI-2h, a double channel magneto-optical filter based full disk imager, EISR a dual channel spectrometer operating in the EUV, and NPA, an in-situ Neutral Particle Analyzer to detect ENA. We shortly present the scientific objectives of the mission, the scientific payload packages and a possible mission orbit. Possible dates for the launch are 2012 and 2014, both during the declining phase of solar activity. Title: MISMA inversion of HINODE SOT/SP data. Preliminary results Authors: Viticchiè, B.; Berrilli, F.; Sánchez Almeida, J.; Orozco Suárez, D. Bibcode: 2009MmSAI..80..255V Altcode: We analyze full Stokes observations of a quiet Sun region at disk center taken with the spectropolarimeter of the Solar Optical Telescope aboard the HINODE satellite. We present the preliminary results derived from the MISMA inversion of the observed Stokes I and V profiles. The complete analysis has as a final goal the definition of probability density function for the statistical description of the quiet Sun magnetic field vector for a direct comparison with recently published results. Title: The Void Probability Function in MDI magnetograms. Authors: Giordano, S.; Berrilli, F.; Del Moro, D. Bibcode: 2009MmSAI..80..289G Altcode: We investigate the spatial distribution of reticular clusters of magnetic features on the solar surface. For this purpose, we develop a void searching algorithm, such as those used in cosmology to study galaxy spatial distributions. We apply this method to a temporal series of large FoV MDI (Michelson Doppler Imager) magnetograms, to identify voids between magnetic structures and to extract their normalized Void Probability Function, which characterizes the scale distribution of magnetic inter-cluster voids. The histogram of the void dimensions shows a pronounced peak for small dimensions (1.76 Mm) and a large spread in the individual cell sizes, up to ≃ 60 Mm. Title: The photospheric structure of a solar pore with light bridge Authors: Giordano, S.; Berrilli, F.; Del Moro, D.; Penza, V. Bibcode: 2008A&A...489..747G Altcode: 2007arXiv0705.3776G Context: Pores are among the photospheric features that form when the magnetic field emerges onto the solar surface. In pores or sunspots, light bridges are bright features that separate umbral areas into two or more irregular regions.
Aims: We study the structure of a solar pore (AR10812) with a light bridge.
Methods: We analyzed both broad-band and narrow-band images acquired with the Interferometric BI-dimensional Spectrometer at the adaptive optics channel of the NSO/Dunn Solar Telescope. Narrow-band images acquired in the photospheric Fe I 709.04 nm line were used to determine the line-of-sight velocity field.
Results: The roundish shape of the pore allows us to derive the radial profiles of both intensity and vertical velocity. The pore has a downward velocity, of about -200 m s-1, and is surrounded by an annular downflow structure with an average velocity of about -300 m s-1 with respect to the nearby quiet sun. The light bridge shows a long narrow dark structure running along its axis. Corresponding to this dark lane, we measure a weak upflow of about 70 m s-1, flanked by a downflow of about 150 m s-1 with respect to the pore. The topology of this velocity structure resembles a convective roll. The anticorrelation between continuum intensity and photospheric velocity may be due to the higher gas pressure in a photospheric field-free cusp, above the light bridge, located between two magnetic walls. We present an analytical model capable of reproducing the observations. Title: Magnetic field distribution in the quiet Sun: a simplified model approach Authors: Berrilli, F.; Del Moro, D.; Viticchiè, B. Bibcode: 2008A&A...489..763B Altcode: 2008arXiv0807.1625B Context: The quiet Sun presents magnetized plasma whose field strengths vary from zero to about 2 kG. The probability density function of the magnetic field strength B efficaciously describes the statistical properties of the quiet Sun magnetic field.
Aims: We simulate the dynamics and the evolution of quiet Sun magnetic elements to produce a probability density function of the field strengths associated with such elements.
Methods: The dynamics of the magnetic field are simulated by means of a numerical model in which magnetic elements are driven passively by an advection field characterized by spatio-temporal correlations that mimick the granulation and mesogranulation scales observed on the solar surface. The field strength can increase due to an amplification process that occurs where the magnetic elements converge. Starting from a δ-like probability density function centered on B=30 G, we obtain magnetic field strengths of up to 2 kG (in absolute value). To derive the statistical properties of the magnetic elements, several simulation runs are performed.
Results: Our model is able to produce kG magnetic fields in a time interval of the order of the granulation timescale. The mean unsigned flux density and the mean magnetic energy density of the synthetic quiet Sun reach values of < B > ≃ 100 G and < B2 >1/2≃ 350 G respectively in the stationary regime. The derived probability density function of the magnetic field strength decreases rapidly from B=30 G to B ∼ 100 G and has a secondary maximum at B=2 kG. From this result, it follows that magnetic fields ≥700 G dominate the unsigned flux density and magnetic energy density, although the probability density function of the field strength reaches a maximum at B ∼ 10 G.
Conclusions: A photospheric advection field with spatio-temporal correlations, driving the magnetic elements, and reduced magnetic amplification rules are able to create a realistic probability density function of the quiet Sun magnetic field. It has been found that they naturally produce an excess of magnetic fields around 2 kG if an upper limit is imposed on the field strength. Title: Studying the decay phase of a short-lived active region with coordinated DST/IBIS, Hinode/EIS+SOT+XRT, SOHO/MDI and TRACE observations Authors: Zuccarello, F.; Berrilli, F.; Centrone, M.; Contarino, L.; Criscuoli, S.; Del Moro, D.; Ermolli, I.; Giorgi, F.; Guglielmino, L. S.; Salerno, C.; Spadaro, D.; Romano, P. Bibcode: 2008ESPM...12.2.56Z Altcode: This study concerns the physical processes occurring during the decay phase of the short-lived active region NOAA 10977, as evaluated from analysis of data gathered using ground- (DST/IBIS) and space-based (Hinode/EIS+SOT+XRT, SOHO/MDI and TRACE) facilities. The coordinated observing campaign was performed from December 1st to 9th, 2007, covering several spectral ranges, with unprecedented spatial and spectral resolution. We present preliminary results of the Doppler analysis of plasma motions evaluated from monochromatic images taken along the Ca II (8542 Å) and the Fe I (7049 Å) spectral lines with IBIS. We also report results concerning the horizontal displacements of photospheric magnetic structures and advection flows as obtained from application of Local Correlation Tracking (LCT) and Two-Level Structure Tracking (TST) techniques to both the LoS magnetograms taken by MDI and to high resolution intensity maps obtained by IBIS at DST/NSO.

Further contributions to understanding the mechanisms at the base of the magnetic field diffusion are provided from the inversion of the Stokes profiles of the photospheric Fe I lines at 6301.5 Å and 6302.5 Å, obtained with SOT/SP, and the analysis of filtergrams in the core of the Ca II H line (3968.5 ± 3 Å) and images in G-band (4305 ± 8 Å) taken by SOT/BFI, as well as EIS data and images taken by the thin Be of XRT, and by TRACE at 171 Å and 1600 Å. Title: The ADAHELI Solar Mission Authors: Berrilli, F.; Velli, M.; Roselli, L.; Bigazzi, A.; Moretti, P. F.; Romoli, M.; Orsini, S.; Cavallini, F.; Greco, V.; Carbone, V.; Consolini, G.; Di Mauro, M. P.; Ermolli, I.; Pietropaolo, E.; Romano, P.; Ventura, P.; White, S. M.; Zuccarello, F.; Cauzzi, G.; Valdettaro, L. Bibcode: 2008ESPM...12..6.6B Altcode: ADAHELI (Advanced Astronomy for HELIOphysics) is an Italian Space project for the investigation of solar photospheric and chromospheric dynamics, via high-resolution spectro-polarimetric observations in the near-infrared spectral range. The mission has been financed for phase A study in the framework of ASI Italian Space Agency Small Missions Program call of September 2007.

Four fields have been selected to highlight the specific benefits of ADAHELI scientific payload: 1) Photospheric and chromospheric dynamics and structure, 2) Emergence and evolution of solar active regions and solar irradiance, 3) Chromospheric and corona heating and turbulence, 4) Solar flares in the millimeter wavelength region.

The principal science instrument, ISODY, is a 50 cm solar telescope equipped with an innovative Focal Plane Suite composed of a spectro-polarimetric imager, based upon two Fabry-Perot interferometers operating in the NIR regions around 845nm and 1083nm, a broad band imager, and a correlation tracker used as image stabilization system.

Designed Mission Profiles for ADAHELI intend to achieve continuous high-spectral and spatial resolution observations of the Sun for a routine duration of 4 hours with a goal to be extended to 24 hours.

ADAHELI also carries MIOS, a millimeter wavelengths radiometer operating at around 90 GHz for flare detection.

The ADAHELI payload's instrument suite integrates and complements, without overlap, the present major objectives of ESA, NASA and the International Living with a Star program, in particular Solar Dynamics Observatory, PICARD, Solar Orbiter, and the Solar Probe missions.

Proposals for optional instruments are also under evaluation: DIMMI-2h, a double channel MOF based full disk imager operating at 589nm and 770nm, allowing high temporal resolution velocity and magnetic field measurements; EISR a two channel spectrometer operating in the 50-130 nm wavelength range, and NPA, an in-situ Neutral Particle Analyzer to detect Energetic Neutral Atoms (ENA). Science objectives related to optional instruments include: solar high and low-degree p modes oscillations, EUV solar structures and variability, solar gravitational red-shift measurement, detection of ENA originating from the plasma region in the Earth's magnetosphere and undergoing reflection from the Earth's atmosphere. Title: MISMA inversion of HINODE SOT/SP and IBIS data: Preliminary Results Authors: Viticchiè, B.; Berrilli, F.; Sanchez Almeida, J.; Del Moro, D. Bibcode: 2008ESPM...12.2.33V Altcode: We present the preliminary results derived from the MISMA inversion of Stokes I and V profiles of FeI 630.1nm FeI 630.2nm lines observed with:

1. SOT/SP instrument aboard the HINODE satellite.

2. IBIS in spectropolarimetric mode imaging, supported by simultaneous white light and G-band images, for blind deconvolution reconstruction.

The complete analysis has as a final goal the comparison of the results obtained from the analysis of the two datasets for a reliable statistical description of the quiet Sun through the definition of a probability density function. Title: Radiative Properties of Magnetic Elements at the Spectral Range of the Ni I 676.8 nm Line Authors: Ermolli, I.; Centrone, M.; Criscuoli, S.; Giorgi, F.; Berrilli, F.; Del Moro, D. Bibcode: 2008ESPM...12.2.48E Altcode: We present measurements of the radiative properties of magnetic elements at some spectral ranges, including the NiI 676.8 nm line. This mid-photospheric absorption line is used to derive the continuum intensity data and helioseismic measurements provided by the MDI and GONG instruments, respectively. We show the results obtained from the analysis of high resolution spatial and spectral measurement of two magnetic regions observed on November 2007 at DST/IBIS. We investigate the line profile changes in presence of magnetic field. We quantify the effects of such changes in the continuum intensity derived by SOI/MDI measurements. Title: Improvements in Solar Adaptive Optics Correction using Short-time Turbulence Forecasting Authors: Stangalini, M.; Del Moro, D.; Berrilli, F. Bibcode: 2008ESPM...12.2.75S Altcode: Time delay error and integration time effects play a crucial role in Solar Adaptive Optics systems.

By using a multi-layer turbulence simulation we studied temporal variations of atmospheric turbulence. We simulated Shack-Hartmann wavefront sensing with Zernike and Kharunen-Loeve modal expansions too.

These two sets of polynomial basis have been defined over an annular pupil with a large central obscurament, which is a common feature in Ritchey-Chretien optical configuration.

We found that Karhunen-Loeve functions, defined using principal component analisys methods as a linear combination of Zernike modes, represent the best choice for wavefront reconstruction, giving us the possibility of reducing fitting error with respect to Zernike modal expansion.

Finally, we tested the possibility to use auto-regressive moving average time series models to provide short time forecasting for Zernike or Karhunen-Loeve coefficients. This scheme may be very helpful in improving correction bandwidth and overcoming time delay errors in next generation solar Adaptive Optics systems.

These preliminary results could be particularly important in developing and studying design and performance for next European Solar Telescope. Title: Quiet-Sun Magnetic Field Measurements Based on Lines with Hyperfine Structure Authors: Sánchez Almeida, J.; Viticchié, B.; Landi Degl'Innocenti, E.; Berrilli, F. Bibcode: 2008ApJ...675..906S Altcode: 2007arXiv0710.5393S The Zeeman pattern of Mn I lines is sensitive to hyperfine structure (HFS), and because of this, they respond to hectogauss magnetic field strengths differently than the lines commonly used in solar magnetometry. This peculiarity has been employed to measure magnetic field strengths in quiet-Sun regions, assuming the magnetic field to be constant over a resolution element. This assumption is clearly insufficient, biasing the measurements. The diagnostic potential of Mn I lines can be fully exploited only after one understands the sense and magnitude of such bias. We present the first syntheses of Mn I lines in realistic quiet-Sun model atmospheres. The Mn I lines weaken with increasing field strength. In particular, kilogauss magnetic concentrations produce Mn I λ5538 circular polarization signals (Stokes V) that can be up to 2 orders of magnitude smaller than what the weak magnetic field approximation predicts. The polarization emerging from an atmosphere having weak and strong fields is biased toward the weak fields, and HFS features characteristic of weak fields show up even when the magnetic flux and energy are dominated by kilogauss fields. For the HFS feature of Mn I λ5538 to disappear, the filling factor of kilogauss fields has to be larger than the filling factor of subkilogauss fields. Since the Mn I lines are usually weak, Stokes V depends on magnetic field inclination according to the simple cosine law. Atmospheres with unresolved velocities produce very asymmetric line profiles, which cannot be reproduced by simple one-component model atmospheres. Using the HFS constants available in the literature, we reproduce the observed line profiles of nine lines with varied HFS patterns. Title: ADAHELI: Investigating the structure of Sun's lower atmosphere and solar irradiance Authors: Bigazzi, Alberto; Velli, Marco; Berrilli, Francesco; Egidi, Alberto; Alimenti, Federico; Roselli, Luca Bibcode: 2008cosp...37..291B Altcode: 2008cosp.meet..291B A new solar Mission ADAHELI (ADvanced Astronomy for HELIophysics) has just been approved for Phase A feasibility study by the Italian Space Agency (ASI), on its call for two new "Small Missions". ADAHELI will study the dynamics and structure of the solar photosphere and chromosphere, in the Near Infrared (NIR) and address solar variability issues in the NIR. A Millimiter Waves (mmW) interferometer will monitor irradiance in selected bands in the range 60-120 GHz. The possibility of an additional UV payload is also being addressed. ADAHELI's Sun-synchronous orbit shall guarantee continuous observation of the Sun during three years of operations, planned to start by 2011-2012, possibly the peak of Solar Cycle XXIV. Title: Intensity and Velocity Structure of a Light Bridge in a Pore Seen by IBIS at NSO/DST: Analysis and Interpretation Authors: Berrilli, F.; Giordano, S.; Del Moro, D.; Penza, V. Bibcode: 2007AGUFMSH22A0844B Altcode: Light bridges are bright structures separating umbral areas of pores or sunspots in two or more sub-regions. We analyze intensity and velocity small scale properties of a light bridge, observed in the pore AR10812, using both broad-band and monochromatic images acquired with the Interferometric BI-dimensional Spectrometer (IBIS) at the adaptive optics channel of the NSO/Dunn Solar Telescope. The observed pore shows a mean downward velocity of about -200 m/s and an external annulus with average downward velocity of -350 m/s. Besides, an elongated dark structure along light bridge axis matches a feeble upward plasma structure of about +100 m/s. We interpret this sort of reversed convective feature as a consequence of the higher gas pressure in a photospheric field-free cusp, above the light bridge, located between two magnetic walls. To reproduce this configuration, we developed a simple light bridge thermal model in which we consider a quiet field free region below a partially emptied of plasma magnetic region. Title: Numerical Simulations of Nanoflares: PDFs of Released Energy, Waiting Times and Quiet- Sun Magnetic Field Elements Authors: Egidi, A.; Viticchie`, B.; Berrilli, F.; Del Moro, D. Bibcode: 2007AGUFMSH22A0850E Altcode: A numerical model for nanoflares is proposed to describe probability density functions (PDF) and waiting time statistics of the emitted magnetic energy and to guess PDF of quiet-Sun magnetic field strength. In the simulation, footpoints of reconnecting magnetic loops are advected by photospheric flows computed via a n-body algorithm. The model simulates a system whose behavior is characterized by small scale (i.e., granulation) flows that interact to develop large organization scales (i.e., mesogranulation). Such spatio-temporal correlated flows, incessantly supply , remove and convey the passive magnetic footpoints onto the photospheric surface, triggering reconnections and magnetic field reconfigurations. Title: 3D photospheric velocity field of a supergranular cell Authors: Del Moro, D.; Giordano, S.; Berrilli, F. Bibcode: 2007A&A...472..599D Altcode: 2007arXiv0704.0578D Aims:We investigate the plasma flow properties inside a supergranular (SG) cell, in particular its interaction with small-scale magnetic field structures.
Methods: The SG cell has been identified using the magnetic network (CaII wing brightness) as a proxy, applying Two-Level Structure Tracking (TST) to high spatial, spectral and temporal resolution observations obtained by IBIS. The full 3D velocity vector field for the SG has been reconstructed at two different photospheric heights. We also computed the mean radial flow of the SG by cork tracing and studied the behaviour of the horizontal and Line of Sight plasma flow cospatial with the cluster of bright CaII structures of magnetic origin to better understand the interaction between photospheric convection and small-scale magnetic features.
Results: The SG cell we investigated seems to be organized with an almost radial flow from its centre to the border. The large-scale divergence structure is probably created by a compact region of constant up-flow close to the cell centre. On the edge of the SG, isolated regions of strong convergent flow are nearby or cospatial with extended clusters of bright CaII wing features forming the knots of the magnetic network. Title: A Pixel Silicon Detector For Charge Identification In Solar Energetic Particles Onboard Solar Orbiter Authors: Sparvoli, R.; Basili, A.; Berrilli, F.; Bidoli, V.; Casolino, M.; Del Moro, D.; De Pascale, M.; Egidi, A.; Froysland, T.; Giordano, S.; Marcelli, L.; Malvezzi, V.; Minori, M.; Picozza, P.; Reali, E.; Viticchie, B.; Bonvicini, V.; Castellini, G. Bibcode: 2007ESASP.641E..91S Altcode: The Energetic Particle Detector (EPD) on board the Solar Orbiter represents an excellent chance to study Solar Energetic Particles, solar modulation effects and cosmic ray gradients from an unique observation point. The development of silicon detector technology and electronics allows the nuclear and isotopic components of solar and galactic cosmic rays to be studied in growing detail. The WiZard collaboration has been involved in the development of space borne detectors for the study of cosmic rays in space for many years. This collaboration, together with the Solar and Space Physics group of the University of Rome Tor Vergata (Italy), is interested in contributing to the realization of the Energetic Particle Detector, build- ng the High Energy Telescope HETn, to observe charged particles associated to SEPs. The realization of the HETn would make use of the most recent technologies to cope with the challenging conditions posed by SOLO. Title: Dynamics of a solar pore with light bridge Authors: Giordano, S.; Berrilli, F.; Del Moro, D.; Penza, V. Bibcode: 2007msfa.conf..209G Altcode: Pores are one of numerous features formed by the emerging of magnetic field from the solar surface. Their uniqueness derives from the fact that as far as size is concerned they lie between the tiny flux tubes associated with magnetic elements, and the complex and large magnetic regions associated with sunspots. Light bridges, in a pore or a sunspot, are bright features dividing the umbral region in a more or less complex structure. Commonly, light bridges indicate that inside the active region a process is underway: the merging of magnetic regions or, conversely, the breakup of the area. In both cases a topological reconfiguration of the emerging magnetic field is expected. In this study we investigate the velocity structure of a solar pore with light bridge and of the quiet solar photosphere around it by means of high spatial and spectral resolution data obtained with the Interferometric BI-dimensional Spectrometer (IBIS) at the Dunn Solar Telescope of the NSO. We observe that the amplitude of the LOS velocities decreases inside the pore with respect to the quiet granulation around the active region, and that the pore exhibits a downflow ring-shaped structure in the surrounding region. We also observe an average downward flow from the light bridge into the umbra. Title: Photospheric Dynamic Model of Magnetic Reconnection Authors: Berrilli, F.; Viticchiè, B.; Del Moro, D.; Egidi, A. Bibcode: 2006ASPC..358...76B Altcode: We present a dynamic model of the atmospheric magnetic field in which magnetic loop footpoints are controlled by photospheric flows computed through a N-body algorithm. This simulation reproduces a system whose behaviour is characterized by small scale (e.g., granular) advection flows that interact to form large spatial organization scales (e.g., meso- and super-granulation). In this model the passive advection of magnetic footpoints through photospheric spatio-temporal correlated flows causes the magnetic field to reconfigure as a consequence of magnetic reconnection processes. This approach, based on the dynamic model of multiple magnetic loops tep{b8 Hu03} and on an advective-interaction model proposed by tet{b8 Ra03}, naturally accounts for the observed probability distribution functions and waiting time statistics of the emitted magnetic energy. Title: Statistical Properties of Synthetic Nanoflares Authors: Viticchié, B.; Del Moro, D.; Berrilli, F. Bibcode: 2006ApJ...652.1734V Altcode: Statistical properties of flares are a powerful tool for addressing the upper solar atmosphere heating problem. We simulate time series of synthetic flares by means of a dynamic model of the atmospheric magnetic field in which magnetic loop footpoints are controlled by photospheric flows computed through a n-body algorithm. The n-body simulation reproduces the behavior of a system where large spatial organization scales (i.e., mesogranulation) occur from the interaction of small-scale advection flows (i.e., granulation). The frequency function of the emitted magnetic energies obtained from the simulation is well approximated by a power law with index α~2.4, while the frequency function of the waiting times between emissions shows a Poisson-like behavior with a deviation for longer times. The flare model yields a fairly intuitive interpretation of magnetic reconnection processes as magnetic field reconfigurations triggered by passive advection of magnetic footpoints through photospheric space-temporal correlated flows. Title: 3D Reconstruction of Photospheric Velocity Fields Inside a Magnetic Network Cell Authors: Del Moro, D.; Giordano, S.; Berrilli, F. Bibcode: 2006ASPC..358...84D Altcode: A complete insight of the dynamics of the plasma flows and their interaction with the magnetic field is important to understand the solar convective layer. Such an interaction determines the spatial configuration of the magnetic field in the outer layers of the solar atmosphere. In order to investigate the interaction between the photospheric velocity field and emerging magnetic elements, observations with high spatial, spectral, and temporal resolution are necessary. We present a 3D reconstruction of the photospheric velocity field of a quiet region centered on a large scale (∼ 30 Mm) structure of magnetic network and an analysis of the photospheric plasma dynamical properties below a cluster of magnetic structures. Title: The Interferometric Bidimensional Spectrometer (IBIS) Authors: Cauzzi, Gianna; Cavallini, F.; Reardon, K.; Berrilli, F.; Rimmele, T.; IBIS Team Bibcode: 2006SPD....37.0608C Altcode: 2006BAAS...38..226C The Interferometric Bidimensional Spectrometer (IBIS) is an advanced instrument for imaging spectroscopy installed at the Dunn Solar Telescope at NSO/Sacramento Peak. The instrument has been constructed by a consortium of italian institutes and allows for observations of the photosphere and chromosphere at high spatial, spectral, and temporal resolution. Such observations are essential for performing spatial and spectral comparisons with numerical simulations. We will present some of the performance characteristics of the instrument and show some examples of the IBIS data. We will also show some initial results of the recently tested polarimetric mode. IBIS is available for community use as a facility instrument of NSO.IBIS has been funded by the Italian Research Ministry (MIUR), the Italian Institute for Astrophysics (INAF), and the Universities of Florence and Rome. Additional support is provided by the National Solar Observatory. Title: Dynamics of photosphere in presence of magnetic field Authors: Giordano, S.; Berrilli, F.; Del Moro, D. Bibcode: 2006MSAIS...9..100G Altcode: In this paper we report the results of the preliminary analysis of observations carried out with the panoramic monochromator IBIS, installed at the Dunn Solar Telescope, Sacramento Peak (NM), in the spectral lines Ca II 854.2 nm, Fe I 709.0 nm and Fe II 722.4 nm. We analyzed the dynamical properties of a quiet region centered on a large scale (∼ 30 Mm) structure of magnetic network. Title: First results from IBIS: Photosphere dynamics and network magnetic elements Authors: Giordano, S.; Del Moro, D.; Berrilli, F. Bibcode: 2006AdSpR..38..898G Altcode: The panoramic Interferometric BIdimensional Spectrometer IBIS, installed at the Dunn Solar Telescope of NSO-Sacramento Peak (NM), has been employed to investigate the interaction between photospheric flows and network magnetic elements in a supergranular cell near the solar disk center. High spectral resolution observations of the Fe I 709.0 nm and Fe II 722.4 nm spectral lines were used to compute vertical and horizontal velocities of the granulation field at two heights in the photosphere. The same data were used to compute spectral line parameters as core intensity or equivalent width. Monochromatic images on the wing of the Ca II 854.2 nm line are used as proxy of small network magnetic elements. The analysis of photospheric vertical velocities shows that segmented magnetic structures match downward velocities in the iron lines Doppler images. The identical magnetic regions correspond to low contrast features in Fe I 709.0 nm core intensity images. Finally, the horizontal divergence maps show that the supergranule edge is outlined by velocity convergences. Title: SINERGIES, the Italian Network for Ground-Based Observations of Sun-Earth Phenomena . Authors: Amata, E.; Berrilli, F.; Candidi, M.; Cantarano, S.; Centrone, M.; Consolini, G.; Contarino, L.; Criscuoli, S.; De Lauretis, M.; Del Moro, D.; Egidi, A.; Ermolli, I.; Francia, P.; Giordano, S.; Giorgi, F.; Oliviero, M.; Magrí, M.; Marcucci, F.; Massetti, S.; Messerotti, M.; Parisi, M.; Perna, C.; Pietropaolo, E.; Romano, P.; Severino, G.; Spadaro, D.; Storini, M.; Vellante, M.; Villante, U.; Zlobec, P.; Zuccarello, F. Bibcode: 2006MSAIS...9...79A Altcode: Since many years, the complex phenomena occurring on the Sun have been continuously monitored by different and complementary ground based instruments managed by groups of the Italian Astrophysics Community. Recently some of these instruments have started to operate in a coordinated scheme, the Italian Network for Ground-Based Observations of Sun-Earth Phenomena. In this paper, we describe the characteristics of the nodes belonging to the Network, called SINERGIES, the scientific objectives, the facilities and the data storage system of the Network itself. Due to its capabilities, the Network allows the Italian Solar Terrestrial Physics Community to monitor solar activity and its effect on the Earth. Title: Simulation of atmospheric magnetic reconnections via a dynamic model of photosphere Authors: Viticchié, B.; Del Moro, D.; Berrilli, F.; Egidi, A. Bibcode: 2006MSAIS...9...67V Altcode: We present a dynamic model of atmospheric magnetic field in which magnetic loop footpoints are advected by a velocity field computed using a simple n-body simulation and reproducing large spatial organization scales (e.g. mesogranulation). In this numerical simulation, the advection of passive magnetic elements triggers reconnection processes (occasionally multiple ones) forcing magnetic field reconfigurations and ensuing fluctuations of total magnetic energy. Our simple model reproduces a system with scale-free properties and provides probability distribution functions for emitted magnetic energies described by a power-law index alpha ∼ 2.4. Title: Spatial Clustering of Photospheric Structures Authors: Berrilli, F.; Del Moro, D.; Russo, S.; Consolini, G.; Straus, Th. Bibcode: 2005ApJ...632..677B Altcode: The study of large-scale structures existing in solar photospheric flows provides an essential tool for constraining the models of solar and stellar convection and for understanding physical processes that are at the basis of solar variability. Recent convection models and N-body dynamic simulations predict the evolution of small-scale features (i.e., granules) into large-scale ones. In this work we address the question of the emergence of large spatial scale patterns as a direct consequence of the organization of small-scale plasma flows on time periods longer than the mean granular lifetime. Our analysis reveals that the photospheric dynamics plays a key role in structuring stable intensity features and suggests that surface flows organize small-scale plasma structures, sweeping them up to form clusters of recurrent and stable granular features. Using a quite novel statistical method, the hexagonal normalized information entropy, we establish that sites where recurrent and stable granular features are observed exhibit a clustering spatial scale of about 8 Mm and timescale around 10 minutes. Title: Segmentation Of Photospheric And Chromospheric Solar Features Authors: Berrilli, F.; Moro, D. Del; Florio, A.; Santillo, L. Bibcode: 2005SoPh..228...81B Altcode: We describe the application of a multi-scale Laplacian-of-Gaussian (LoG) operator and of an iterative version of Medial Axis Transform (i-MAT) as tools for the segmentation of both photospheric and chromospheric solar features. We introduce the multi-scale LoG operator in order to extract compact structures in photospheric intensity or Doppler images. The second method, based on a i-MAT algorithm applied to gray level images, is introduced to recognize reticulated structures like chromospheric network or intergranular lanes. The developed numerical procedures allow a non-subjective segmentation of solar images in order to investigate morphological and topological properties of identified features. We discuss the output of the segmentation procedures when applied to real images. Title: High resolution observations of chromospheric network Authors: Giordano, S.; Berrilli, F.; Del Moro, D. Bibcode: 2005MmSAI..76..973G Altcode: There is an increasing evidence that primary driver of solar variability, on time scales of days up to the solar activity cycle length, is the evolution of magnetic field present on the solar surface. In this paper we investigate the correlation between the photospheric structures and emerging magnetic elements by means of high spectral resolution images containing network cells. We present the preliminary results derived from the analysis of observations carried out in the spectral lines Ca II 854.3 nm, Fe I 709.0 nm and Fe II 722.4 nm with the 2-D Interferometric Bidimensional Spectrometer IBIS installed at the DST - Dunn Solar Telescope, Sacramento Peak (NM). Title: Magnetic reconnection driven by a synthetic photospheric velocity field Authors: Viticchié, B.; Del Moro, D.; Berrilli, F.; Egidi, A. Bibcode: 2005MmSAI..76.1068V Altcode: We present a dynamic model of atmospheric magnetic field in which magnetic loop footpoints are advected by a velocity field computed using a simple n-body simulation and reproducing large spatial organization scales (e.g. mesogranulation). In this model, the advection of passive magnetic elements triggers multiple reconnection processes forcing magnetic field reconfigurations and ensuing fluctuations of total magnetic energy. The simulations reproduce a system with scale-free properties, provides frequency distribution functions for emitted magnetic energies, described by a power-law index alpha ∼ 2.4, and also frequency distribution for quiescent times between different energy emissions. Title: Structure Properties of Supergranulation and Granulation Authors: Berrilli, F.; Del Moro, D.; Consolini, G.; Pietropaolo, E.; Duvall, T. L., Jr.; Kosovichev, A. G. Bibcode: 2004SoPh..221...33B Altcode: We investigate spatial dislocation ordering of the solar structures associated with supergranulation and granulation scales. The supergranular and granular structures are automatically segmented from time-distance divergence maps and from broad-band images, respectively. The spatial dislocation ordering analysis is accomplished by applying the statistical method of Pair Correlation Function, g2(r), to segmented features in the solar fields. We compare the computed g2(r) functions obtained from both single and persistent, i.e., time-averaged, fields associated with supergranulation and granulation. We conclude that supergranulation and granulation patterns present a different topological order both in single and persistent fields. The analysis carried out on single fields suggests that the granulation behaves as an essentially random distribution of soft plasma features with a very broad distribution in size, while supergranulation behaves as a random distribution of close packed, coherent stiff features with a rather defined mean size. Title: Dynamics and Structure of Supergranulation Authors: Del Moro, D.; Berrilli, F.; Duvall, T. L., Jr.; Kosovichev, A. G. Bibcode: 2004SoPh..221...23D Altcode: In this paper we investigate the temporal evolution and geometric properties of solar supergranular features. For this purpose we apply an automatic feature-tracking algorithm to a 6-day time series of 18 near-surface flowmaps containing 548 target objects. Lifetimes are calculated by measuring the time elapsing between the birth and death of each target. Using an exponential fit on the lifetime distribution of single supergranules we derived a mean lifetime of 22 hours. Based on the application of segmentation numerical procedures, we estimated characteristic geometric parameters such as area distributions of supergranular cells. We also derive the relationship between measured lifetime and the area of the supergranules. Title: Magnetic network dynamics in photosphere Authors: Berrilli, F.; del Moro, D.; Pietropaolo, E.; Consolini, G. Bibcode: 2004cosp...35.2814B Altcode: 2004cosp.meet.2814B In order to investigate the interaction between the photospheric velocity field and emerging magnetic elements, observations with high spectral and temporal resolution and with a spatial scale of about 100 km on the solar surface are necessary. The convective advection of magnetic elements produces the magnetic network which is a key component of solar irradiance and of the energy transport toward the solar upper atmosphere. Furthermore, the magnetic network structures are suspected to be the roots of solar wind emanating from localized regions along boundaries of magnetic network cells. We present the results of the preliminary analysis of observations carried out with the panoramic monochromator IBIS, installed at the Dunn Solar Telescope, Sacramento Peak (NM), in the spectral lines Ca II 854.2 nm, Fe I 709.0 nm, and Fe II 722.4 nm. Title: A measure of the network radiative properties over the solar activity cycle Authors: Ermolli, I.; Berrilli, F.; Florio, A. Bibcode: 2003A&A...412..857E Altcode: Magnetic activity contributes to solar irradiance variations, both on short and long time scales. While sunspots and active region faculae are the dominant contributors to irradiance changes on time scales of days to weeks, the origin of the long term increase of the irradiance between activity minimum and maximum (~0.1%) is still debated. It has been proposed that the small-scale magnetic elements composing the enhanced and quiet network take part substantially in this increase. To contribute to this debate, we present the results obtained measuring changes in the radiative properties of the quiet network pattern along the current solar cycle. We use daily near simultaneous full-disk images provided by the Rome PSPT in three pass bands centered on CaII K line, blue and red Continua. The period analyzed ranges from July 1996 to September 2002, during the whole ascending phase of the current solar cycle. We measured a network contrast change of about 0.05% in the two continuum PSPT bands and a network disk coverage change of the order of 6%. Under the simple hypothesis that network and quiet sun radiate as black bodies with the network at a slightly elevated temperature, the network contribution to TSI cycle variation, estimated over the period analyzed, is ~3-4 x 10-4. Title: Characterization of supergranular features via topological measures Authors: Berrilli, F.; del Moro, D.; Giordano, S.; Consolini, G.; Kosovichev, A. Bibcode: 2003ESASP.535...47B Altcode: 2003iscs.symp...47B The spatial configuration of enhanced magnetic field (active regions) in the outer layers of the Sun derives from the interaction between convective flows and solar magnetic field. Temporal evolution of active regions is considered the main responsible of radiative output variations. Particularly, solar irradiance variations are explained in terms of temporal and spatial evolution of solar surface magnetic fields. A key role in this evolution is played by supergranular convective flow that, advecting magnetic flux tubes, is also responsible of the creation of the magnetic network. This latter results located on the boundaries of supergranular cells. In order to measure both the spatial correlation length in supergranular structures and the degree of near neighbor order in such structures, we employ two topological analysis methods, the Pair Correlation Function g2(r) and the Information Entropy H'(l). More in detail, we apply these statistical methods to segmented images of divergence maps derived from the application of the time-distance technique to MDI/SOHO data. We assume that segmented images are representative of the mass flows associated to convective supergranular motions. Title: The Detection of Photospheric Impacts from Chromospheric Impulsive Events Authors: Moretti, P. F.; Berrilli, F.; Sebastianelli, A.; Briand, C.; Pietropaolo, E. Bibcode: 2003ApJ...589L.109M Altcode: Multiwavelength solar observations were carried out at the THEMIS telescope in order to investigate the propagation of the plasma jets during and after a flare occurrence. The data obtained in the Hα, Na I D2, and Fe I 557.6 nm lines show that the perturbations detected in the higher layers due to a B-class flare do penetrate down to the photosphere. The observational evidence of such perturbations is crucial for the identification of the source of the solar oscillations. Title: Information entropy in solar atmospheric fields. I. Intensity photospheric structures Authors: Consolini, G.; Berrilli, F.; Florio, A.; Pietropaolo, E.; Smaldone, L. A. Bibcode: 2003A&A...402.1115C Altcode: The existence of a quasi-regular pattern in solar photospheric convective fields is an open question. In the present work, this problem is quantitatively approached by means of the normalised information entropy measure H'(r) as introduced by Van Siclen (\cite{VanSic97}), which reports on the information content at different scales. Images were acquired at the THEMIS telescope of the European Northern Observatory by the IPM observing mode, and at the Richard B. Dunn Solar Telescope of the National Solar Observatory. The evaluation of H'(r) in the case of photospheric intensity binarized images shows the presence of maxima which are evidence of different prominent scales in the photospheric pattern. The relative positions of these maxima defines an ordering scale ~ 1.6 Mm in both instantaneous and average images. This is read as the evidence of a spatio-temporal organization in the evolution of convective pattern. The emergence of an ordering scale is discussed in the framework of pattern formation in random systems and in connection with the findings of previous works. By averaging images with time, an increase of the information content characterized by a coherence time of ~ 1 h is observed in the range of scales from 5.0 Mm to 10.0 Mm. Title: Granule and Supergranule properties derived from solar timeseries Authors: Del Moro, D.; Berrilli, F.; Bonet, J. A.; Consolini, G.; Kosovichev, A.; Pietropaolo, E. Bibcode: 2003MmSAI..74..584D Altcode: In this paper we mainly aim at the understanding of temporal evolution and spatial characterization of solar granular and supergranular features. For this purpose we apply an automatic feature-tracking algorithm to three different solar granulation timeseries and to a supergranular timeseries of near-surface divergence fields. The single lifetimes are calculated measuring the time elapsing between the birth and death of each target. In addition, we investigate spatial order of surface flows studying the g2(r) function of time-averaged supergranular fields. Title: Recent results from IBIS Authors: Cavallini, F.; Baffa, C.; Reardon, K.; Berrilli, F.; Cantarano, S.; Egidi, A. Bibcode: 2003MmSAI..74..796C Altcode: IBIS (Interferometric BIdimensional Spectrometer) is a new instrument for solar bidimensional spectroscopy. It essentially consists of two Fabry-Perot interferometers, piezo-scanned and capacity servo-controlled, used in classic mount and in axial-mode, in series with a set of narrow-band interference filters. This instrument will operate on a large field of view (80") and on a large wavelength range (580 - 860 nm), with high spectral, spatial and temporal resolution. IBIS, developed to become one of the focal plane instruments of THEMIS, has been completed in its essential form and some tests have been already performed. It is now possible therefore to compare expected with measured values of the more relevant instrumental parameters. Title: Granulation structure and information entropy Authors: Berrilli, F.; Consolini, G.; Florio, A.; Del Moro, D.; Pietropaolo, E. Bibcode: 2003AN....324..405B Altcode: No abstract at ADS Title: CONCORDIASTRO/Italy: A Solar High-Resolution Observation Program at Dome-C Authors: Severino, G.; Andretta, V.; Berrilli, F.; Cascone, E.; Centrone, M.; Criscuoli, S.; Del Moro, D.; Ermolli, I.; Giorgi, F.; Jefferies, S. M.; Magri, M.; Moretti, P. F.; Oliviero, M.; Parisi, L.; V; Porzio; Smaldone, L. A.; Straus, Th. Bibcode: 2003MSAIS...2..181S Altcode: CONCORDIASTRO is the Nice-Napoli joint project for site testing of the Dome C for solar and stellar astronomy in the visible. CONCORDIASTRO/Italy is the solar physics part of this project, whose the Napoli team has the principal responsibility. Beyond the well-known interest for the helioseismology, CONCORDIASTRO/Italy pointed out that, because of its special atmospheric conditions, Dome C promises to be one of the best sites on Earth to perform high-resolution solar physics. Here we review the basis for this statement and the solar observations program planned by CONCORDIASTRO/Italy. Title: Spatio-temporal patterns in solar surface convection Authors: Berrilli, F. Bibcode: 2003MmSAI..74..576B Altcode: The solar plasma, under the control of convective motions, concentrates or diffuses the magnetic field emergent on the solar surface. The convection and magnetism, closely interacting, govern the activity we observe on the Sun. Commonly, on the solar surface, three different convective scales are indicated: the granulation, with a typical length of about 1-2 Mm, the mesogranulation, that ranges from 3 Mm to 10 Mm, and the supergranulation, with typical length scales of 20-30 Mm. Recently, the physical framework of convection has been challenged and the processes at the base of the formation and evolution of solar features have been remarkably re-examined. In fact, even though in various measure, for all three scales a "classical" convective origin seems not sufficient to hold account of the complex observational and theoretical scenery. The recent progresses in observational techniques, laboratory experiments, and numerical simulations produce a more complex scheme where hydrodynamic instabilities, hard-turbulence regimes, cooperative evolution, play a dominant role in the description of onset and evolution of observed spatio-temporal patterns in the Sun.\ After a brief review of the physics involved in the convection onset in the solar interior, some recent conclusions related to the three different convective scales are discussed. Title: CMOS detectors at Rome "Tor Vergata" University Authors: Berrilli, F.; Cantarano, S.; Egidi, A.; Giordano, S. Bibcode: 2003MmSAI..74..804B Altcode: The new class of CMOS panoramic detectors represents an innovative tool for the experimental astronomy of the forthcoming years. While current charge-coupled device (CCD) technology can produce nearly ideal detectors for astronomical use, the scientific quality CMOS detectors made today have characteristics similar to those of CCD devices but a simpler electronics and a reduced cost. Moreover, the high frame rate capability and the amplification of each pixel - active pixel - in a CMOS detector, allows the implementation of a specific data management. So, it is possible to design cameras with very high dynamic range suitable for the imaging of solar active regions. In fact, in such regions, the onset of a flare can produce problems of saturation in a CCD-based camera. In this work we present the preliminary result obtained with the Tor Vergata C-Cam APS camera used at the University Solar Station. Title: 2-D multiline spectroscopy of the solar photosphere Authors: Berrilli, F.; Consolini, G.; Pietropaolo, E.; Caccin, B.; Penza, V.; Lepreti, F. Bibcode: 2002A&A...381..253B Altcode: The structure and dynamics of the photosphere are investigated, with time series of broadband and monochromatic images of quiet granulation, at the solar disk center. Images were acquired with the IPM observing mode at the THEMIS telescope. Velocity and line center intensity fields, derived from the observation of three different photospheric lines, are used to study velocity and intensity patterns at different heights in the photosphere. Automatic segmentation procedures are applied to velocity and intensity frames to extract solar features, and to investigate the dependence of their properties at different scales and heights. We find a dependence of the statistical properties of upflow and downflow regions on the atmospheric height. Larger granules, passing through a great part of the photosphere, are used to investigate the damping of convective motions in stably stratified layers. The results suggest the occurrence of an intense braking in the deep photosphere (first ~ 120 km). Furthermore, we investigate the temporal and spatial evolution of velocity fields, deriving typical time scales of dynamical processes relative to different solar features. In particular, for two selected isolated exploders, we reveal a velocity deceleration in the central region since the early phase of their fragmentation. Based on observations made with THEMIS-CNRS/INSU-CNR operated on the island of Tenerife by THEMIS S.L. in the Spanish Observatorio del Teide of the Instituto de Astrofisica de Canarias. Title: An analysis of the vertical photospheric velocity field as observed by THEMIS Authors: Carbone, V.; Lepreti, F.; Primavera, L.; Pietropaolo, E.; Berrilli, F.; Consolini, G.; Alfonsi, G.; Bavassano, B.; Bruno, R.; Vecchio, A.; Veltri, P. Bibcode: 2002A&A...381..265C Altcode: We propose the application of Proper Orthogonal Decomposition (POD) analysis to the photospheric vertical velocity field obtained through the data acquired by the THEMIS telescope, to recover a proper optimal basis of functions. As first results we found that four modes, which are energetically dominant, are nearly sufficient to reconstruct both the convective field and the field of the ``5-min'' oscillations. Based on observations made with THEMIS-CNRS/INSU-CNR operated on the island of Tenerife by THEMIS S.L. in the Spanish Observatorio del Teide of the Instituto de Astrofisica de Canarias. Title: Solar Granulation and P-modes Authors: Lepreti, F.; Vecchio, A.; Carbone, V.; Veltri, P.; Primavera, L.; Berrilli, F.; Consolini, G.; Pietropaolo, E. Bibcode: 2002EGSGA..27.6305L Altcode: We apply the Proper Orthogonal Decomposition, a method used to obtain information about coherent structures in turbulent fields, to the photospheric vertical velocity field obtained through the data acquired by the THEMIS telescope. We found that four modes are nearly sufficient to reconstruct both the granulation field and the p-modes. Title: The supergranular intensity contrast Authors: Rast, M.; Ermolli, I.; Sands, J.; Berrilli, F. Bibcode: 2002cosp...34E1110R Altcode: 2002cosp.meetE1110R The Precision Solar Photometric Telescope (PSPT) at Mauna Loa Solar Observatory (MLSO) in Hawaii yields full disk solar images with high (approximately 0.1%/pixel) photometric precision in three wavelength bands: continuum blue, continuum red, and line-center CaIIK. We use this data to measure the intensity contrast associated with network cells. We attempt to disentangle the continuum contributions of the magnetic network from that of the presumed underlying supergranular flow by applying a series of network masks. Granular fluctuations are removed by both temporal averaging of aligned images and spatial averaging of individual cells after resizing. Preliminary results indicate that the network contribution to the continuum is small but measurable in the PSPT data, while the convective contribution lies very near or below detection limits. Title: Analysis of high resolution and full disk solar images Authors: Berrilli, F.; Caccin, B.; Cantarano, S.; Egidi, A.; Penza, V.; Criscuoli, S.; del Moro, D.; Pietropaolo, E.; Consolini, G.; Ermolli, I.; Lepreti, F.; Mainella, G.; Severino, G.; Zuccarello, F. Bibcode: 2001ESASP.493..173B Altcode: 2001sefs.work..173B No abstract at ADS Title: The Magnetic Network Contribution to the Total Solar Irradiance Authors: Ermolli, I.; Berrilli, F.; Florio, A. Bibcode: 2001AGUSM..SP21A03E Altcode: We studied the brightness contrast and the disk coverage of the solar network pattern in the chromosphere and in the photosphere, analyzing the full-disk near simultaneous CaII K, blue and red continuum images obtained daily with the Rome-PSPT telescope. We also done a detailed account of the temporal variation of these network properties from July 1997 to August 2000 during the ascending phase of the Solar Cycle 23. We used the results obtained to estimate the magnetic network contribution to the total solar irradiance (TSI). We obtained that this contribution is about 10-4 at the activity minimum. Besides, we estimated a change of the network contribution to TSI of order 3x 10-4 over the cycle, by the measured temporal variation of the network properties. Title: Dynamics of the Overshooting Photospheric Region from THEMIS-IPM Observations Authors: Berrilli, F.; Consolini, G.; Pietropaolo, E. Bibcode: 2001AGUSM..SP41B01B Altcode: Here, we present the results of our investigation on quiet photospheric fields. We study the features of intensity and velocity solar fields as derived from observations of photospheric lines, obtained at the French-Italian THEMIS telescope (Observatorio del Teide, Tenerife) using the Italian Panoramic Monochromator (IPM). In detail, the vertical dynamics is investigated using monochromatic observations at three spectral lines (C I 538.0, Fe I 537.9, and Fe I 557.6), as representative of three atmospheric heights in the overshooting photosphere. Moreover, granulation properties and horizontal flows are also studied using broad band images. Title: On the Features of the Correlation Time at Different Wave Numbers in the Photosphere Authors: CONSOLINI, G.; BERRILLI, F.; PIETROPAOLO, E.; LEPRETI, F.; CARBONE, V. Bibcode: 2001AGUSM..SP41B08C Altcode: In many turbulent systems the temperature behaves as a passive scalar advected by velocity field. In some previous works, dedicated to the study of the velocity and intensity patterns at the solar photosphere, it has been evidenced the existence of scaling features and intermittency in the spatial properties of the velocity and dissipation fields. Here, using broad-band intensity images acquired at the French-Italian THEMIS telescope (Canarias - Spain) by the Italian Panoramic Monochromator, we investigate the features of the correlation time τ k at different wave numbers k. The results will be compared with the ones coming from field theoretic renormalization group (RG) applied to the problem of advected passive scalar fields. Title: Optimal windows to determine solar granulation image quality Authors: Giammanco, C.; Berrilli, F. Bibcode: 2001MmSAI..72..573G Altcode: We present a new method to determine the quality of solar granulation images. An optimal window for the image analysis is determined by means of Information Theory. The size of the window is then used as a good estimator of image quality. The method is sensitive to the size of structures present in the image and can provide a quality map, indicating the zones more or less degraded in the image. Title: Dynamics of the solar granulation Authors: Berrilli, F.; Consolini, G.; Florio, A.; Pietropaolo, E. Bibcode: 2001MmSAI..72..540B Altcode: Temporal series of quiet region images near the center of the Sun are analysed. The images, monochromatic and in white light, have been acquired at the French-Italian solar telescope THEMIS (Tenerife, Canarie, Spain) by the Italian panoramic monochromator IPM. Solar granules evolution and the physical properties of the penetration convective photospheric region are discussed analysing velocity and intensity fields at the center of spectral lines. The observed lines are: C 5380, Fe 5379 and Fe 5576, which represent respectively the low, medium and high solar photosphere. Title: IBIS: a new instrument for solar bidimensional spectroscopy Authors: Cavallini, F.; Berrilli, F.; Cantarano, S.; Egidi, A. Bibcode: 2001MmSAI..72..554C Altcode: IBIS is a new instrument for solar bidimensional spectroscopy, now under construction in Arcetri, which will operate on a large field of view and on a large wavelength range, with high spectral, spatial and temporal resolution. When completed in 2002, it will be one of the leading instruments for solar research, well suited for new generation telescopes such as THEMIS. Title: Solar granulation: properties of velocity fields from THEMIS-IPM observations Authors: Berrilli, Francesco; Consolini, Giuseppe; Florio, Arnaldo; Pietropaolo, Ermanno Bibcode: 2001MmSAI..72..669B Altcode: The structure and evolution of the photospheric velocity and intensity field, lying in the convective overshooting region, are investigated on the basis of monochromatic and large bandwidth solar granulation images. The time series of a quiet granulation field, at the Sun center, have been acquired with the IPM Monochromator mounted at the THEMIS telescope in Tenerife (Spain) in July 1999. In specific we investigate both the stratification of relative temperature fluctuations and the evolution of fragmenting granules. The main results that the present analysis seem to suggest are: a) The presence of two photospheric heights at which the intensity (then the temperature) change sign. b) The existence of a deceleration of upward flow, and the following upset of a downflow, in the center of exploding granules near the peak of corresponding large bandwidth intensity profiles. Title: Multifractal structure of the dissipation field of intensity fluctuations in the solar photosphere Authors: Lepreti, F.; Carbone, V.; Pietropaolo, E.; Consolini, G.; Bruno, R.; Bavassano, B.; Berrilli, F. Bibcode: 2000PhyA..280...87L Altcode: We investigate the scaling properties of the photospheric intensity field, using images acquired at the THEMIS telescope with the Italian Panoramic Monochromator. After calculating the power spectrum of the continuum intensity fluctuations, we analyze the scaling laws of the dissipation field obtained from the intensity fluctuations, in analogy with the dissipation of passive scalar fluctuations in turbulent fluids. Using the multifractal formalism, we show that the dissipation is intermittent and that it is characterized by stronger singularities in the higher photosphere than in the lower photosphere. Title: MgIb2 Bright Features in the Solar Photosphere Authors: Berrilli, F.; Bruno, R.; Consolini, G.; Florio, A.; Pietropaolo, E. Bibcode: 2000ESASP.463..285B Altcode: 2000sctc.proc..285B No abstract at ADS Title: The Magnetic Network Contribution to Long-Term Irradiance Variations Authors: Ermolli, I.; Berrilli, F.; Florio, A. Bibcode: 2000ESASP.463..313E Altcode: 2000sctc.proc..313E No abstract at ADS Title: IBIS: A Purely Interferometric Instrument for Solar Bidimensional Spectroscopy Authors: Cavallini, F.; Berrilli, F.; Cantarano, S.; Egidi, A. Bibcode: 2000ESASP.463..607C Altcode: 2000sctc.proc..607C No abstract at ADS Title: Solar Irradiance Variations Associated to Quiet Network Authors: Ermolli, I.; Berrilli, F.; Florio, A. Bibcode: 1999ESASP.448..275E Altcode: 1999ESPM....9..275E; 1999mfsp.conf..275E No abstract at ADS Title: Performances of THEMIS IPM and First Analyses of 1999 Observations Authors: Caccin, B.; Giammanco, C.; Pietropaolo, E.; Berrilli, F.; Ceppatelli, G.; Egidi, A. Bibcode: 1999ESASP.448..235C Altcode: 1999ESPM....9..235C; 1999mfsp.conf..235C No abstract at ADS Title: Characterization of the Solar Photospheric Velocity Field: a New Approach Authors: Consolini, G.; Berrilli, F.; Pietropaolo, E.; Bruno, R.; Carbone, V.; Bavassano, B.; Ceppatelli, G. Bibcode: 1999ESASP.448..209C Altcode: 1999mfsp.conf..209C; 1999ESPM....9..209C No abstract at ADS Title: Calibration of the THEMIS-IPM High Speed Acquisition System Authors: Berrilli, F.; Cantarano, S.; Egidi, A.; Caccin, B. Bibcode: 1999ESASP.448.1301B Altcode: 1999mfsp.conf.1301B; 1999ESPM....9.1301B No abstract at ADS Title: Wavelet Analysis of Spatial Coherent Structures in the Photosphere Authors: Pietropaolo, E.; Berrilli, F.; Consolini, G.; Smaldone, L. A.; Straus, T.; Cauzzi, G.; Bruno, R.; Bavassano, B. Bibcode: 1999ESASP.448..343P Altcode: 1999ESPM....9..343P; 1999mfsp.conf..343P No abstract at ADS Title: Power Spectra and Multifractal Structure of the Intensity Fluctuations in the Solar Photosphere Authors: Lepreti, F.; Carbone, V.; Consolini, G.; Berrilli, F.; Bruno, R.; Bavassano, B.; Ceppatelli, G.; Mainella, G.; Pietropaolo, E. Bibcode: 1999ESASP.448..327L Altcode: 1999mfsp.conf..327L; 1999ESPM....9..327L No abstract at ADS Title: Dynamics of the Photospheric Vertical Flow Authors: Berrilli, F.; Florio, A.; Consolini, G.; Pietropaolo, E.; Bruno, R.; Carbone, V.; Ceppatelli, G. Bibcode: 1999ESASP.448..229B Altcode: 1999ESPM....9..229B; 1999mfsp.conf..229B No abstract at ADS Title: Average properties and temporal variations of the geometry of solar network cells Authors: Berrilli, F.; Ermolli, I.; Florio, A.; Pietropaolo, E. Bibcode: 1999A&A...344..965B Altcode: The average properties of the network cells geometry and their temporal variations are investigated for quiet solar regions at the center of the solar disk. These regions were extracted from the daily Ca II K full-disk observations carried out at the Rome Observatory with the PSPT telescope during one year (from July 1996 to June 1997) at the beginning of Solar Cycle 23. We applied an automated procedure to derive the skeleton of bright Ca II K regions. By using this skeleton as representative of the chromospheric network, we identified and characterized the network cells on the images. The results we found seemed to point out that network cells are regular in shape and slightly flat. We found an upper limit of 2% for the anisotropy of the cell orientation. By analyzing the latitudinal dependence of the cell size, we found that the cell area decreases by about 30% towards the poles. We also characterized the network pattern by using wavelet analysis. We compared the results obtained by the different analyzes. Finally we analyzed the temporal behaviours of the network cell geometrical properties. In particular, we found a decrease of the characteristic scale value of about 8% for the period analyzed. Title: Scaling behavior of the vertical velocity field in the solar photosphere Authors: Consolini, G.; Carbone, V.; Berrilli, F.; Bruno, R.; Bavassano, B.; Briand, C.; Caccin, B.; Ceppatelli, G.; Egidi, A.; Ermolli, I.; Florio, A.; Mainella, G.; Pietropaolo, E. Bibcode: 1999A&A...344L..33C Altcode: We analyze, for the first time, the scaling behavior of the photospheric vertical velocity field. Our analysis is based on data collected by the Italian Panoramic Monocromator (IPM) mounted at the THEMIS telescope at the Spanish ``Observatorio del Teide'' (Tenerife) of the Instituto de Astrofisica de Canarias. We investigate the occurrence of scaling in the cancellations between downflow and upflow of the vertical velocity field, showing that the field possesses well pronunced sign-singularity in the range of scales from more than 10 Mm down to the granulation scale. Based on THEMIS/CNRS--INSU/CNR telescope observations Title: Dependence of the photospheric vertical flow characteristics on the granule dimension Authors: Berrilli, F.; Florio, A.; Consolini, G.; Bavassano, B.; Briand, C.; Bruno, R.; Caccin, B.; Carbone, V.; Ceppatelli, G.; Egidi, A.; Ermolli, I.; Mainella, G.; Pietropaolo, E. Bibcode: 1999A&A...344L..29B Altcode: The first high spectral resolution and white-light images obtained at the THEMIS telescope with the Italian Panoramic Monochromator (IPM), are analyzed to study intensity and velocity fluctuations in the photosphere of the sun. Monochromatic images, in two spectral ranges around 538.03 nm (C I line) and 557.61 nm (Fe I line), are used to characterize the vertical structure of the photosphere. Granulation cells and granules are obtained by segmentation of white-light images using suitable finding algorithms. We observe the height dependence of velocity vs. intensity fluctuations, and we found a dependence of velocity and intensity on granule dimension. Our results show that granules increase their intensity with dimension in the lower solar photosphere. In the higher photosphere, on the contrary, the intensity decreases with the dimension. Based on THEMIS/CNRS-INSU/CNR telescope observations Title: Italian panoramic monochromator for the THEMIS telescope: the first results and instrument evaluation Authors: Cavallini, Fabio; Berrilli, Francesco; Caccin, Bruno; Cantarano, Sergio; Ceppatelli, Guido; Egidi, Alberto; Righini, Alberto Bibcode: 1998SPIE.3355..940C Altcode: We briefly describe the design and the characteristics of the Italian Panoramic Monochromator installed at the focal plane of the THEMIS telescope built in Izana by a joint venture of the French and Italian National Research Councils. The Panoramic Monochromator substantially is a narrow band filter (approximately equals 22 mAngstrom bandwidth) tunable on the visible spectrum for quasi simultaneous bidimensional spectrometry of the solar atmosphere. The narrow bandwidth is obtained by using a non standard birefringent filter and a Fabry Perot interferometer mounted in series. This assembly has the advantage of the spectral purity of one channel of the Fabry Perot interferometer and a very large free spectral range. Moreover the spectral stability depends on the interferometer, the environment of which may be carefully controlled. The design of this instrument is not really new, but, only now it has been possible to build it thanks to the development of servo controlled Fabry Perot interferometers, which are stable in time and may easily be tuned. The system seems to perform well. It is stable in wavelength and the spectral pass band and stray light are within the expected values, as it may be deduced by very preliminary tests performed at the THEMIS Telescope and in Arcetri (Firenze) at the 'G. B. Donati' solar tower. Title: On the Geometrical Properties of the Chromospheric Network Authors: Berrilli, F.; Florio, A.; Ermolli, I. Bibcode: 1998SoPh..180...29B Altcode: A sequence of Ca-K images obtained in a period of minimum solar activity, from July to November 1996, at the Rome Observatory with the PSPT (Precision Solar Photometric Telescope) prototype instrument have been used to analyze the geometrical properties of cells identified by the chromospheric network. In particular, we used 256 × 256 sub-arrays of the calibrated full-disk PSPT images. These sub-arrays, centered on the solar disk, are reduced to two-levels (binary) images by means of a suitable threshold after an FFT high-pass filtering. A medial axis transform, better known as skeleton, combined with a cellular automaton, is applied to the two-level images, in order to derive the cell boundaries. The regions corresponding to the cells are then filled by a growing algorithm. In this way we can derive a set of output parameters describing the cells geometry. The size distribution of the identified cells shows a continuous increase toward the smaller scales, rather than a small dispersion around a characteristic scale. Nevertheless the analysis of the inter-cell distances and of the area distribution pointed out a characteristic scale (square root of the area) of ± 24 Mm. To describe the cells irregularity and to probe the nature of solar turbulence, we apply a Mandelbrot fractal analysis to such irregularly shaped features. Examining the cell perimeter-area relationship we found the existence of a `critical' area at which a change in the geometrical properties occurs. This area corresponds to the scale of ± 24 Mm. The estimated fractal dimension for cells with area greater than the `critical' one is 1.35. This value, close to that predicted for isobars in the Kolmogorov 3-D turbulent theory, does not exclude a turbulent origin for such cells. The analysis seems to point to a common origin for solar granulation and supergranulation. Title: The Prototype RISE-PSPT Instrument Operating in Rome Authors: Ermolli, I.; Fofi, M.; Bernacchia, C.; Berrilli, F.; Caccin, B.; Egidi, A.; Florio, A. Bibcode: 1998SoPh..177....1E Altcode: The breadboard prototype of the PSPT (Precision Solar Photometric Telescope), built by NSO at Sacramento Peak, has been operating in Rome since February 1996 to test observing procedures and future network operations. In this paper we briefly describe the kind of preliminary data we are deriving from the first observations concerning the contrast histogram and the fractal analysis of the `network cells.' Title: A skeletonizing algorithm for granulation and super-granulation cell finding Authors: Florio, A.; Berrilli, F. Bibcode: 1998MmSAI..69..655F Altcode: No abstract at ADS Title: The Prototype RISE-PSPT Instrument Operating in Rome Authors: Ermolli, I.; Fofi, M.; Bernacchia, C.; Berrilli, F.; Caccin, B.; Egidi, A.; Florio, A. Bibcode: 1998sers.conf....1E Altcode: No abstract at ADS Title: THEMIS-IPM: performance analysis of the system and future developments Authors: Mainella, G.; Bavassano, B.; Berrilli, F.; Briand, C.; Bruno, R.; Caccin, B.; Cantarano, S.; Ceppatelli, G.; Egidi, A. Bibcode: 1998MmSAI..69..659M Altcode: No abstract at ADS Title: Chromospheric Network Properties Derived From One Year of PSPT Images Authors: Ermolli, I.; Berrilli, F.; Florio, A.; Pietropaolo, E. Bibcode: 1998ASPC..140..223E Altcode: 1998ssp..conf..223E No abstract at ADS Title: Geometrical properties of the chromospheric network cells from OAR/PSPT images Authors: Berrilli, F.; Ermolli, I.; Florio, A.; Pietropaolo, E. Bibcode: 1998MmSAI..69..635B Altcode: No abstract at ADS Title: Chromospheric Network Properties On Short Time Scales From PSPT Images Authors: Ermolli, I.; Pietropaolo, E.; Florio, A.; Berrilli, F. Bibcode: 1998ASPC..140..231E Altcode: 1998ssp..conf..231E No abstract at ADS Title: THEMIS-IPM: characterization of the photospheric velocity field Authors: Consolini, G.; Bruno, R.; Bavassano, B.; Mainella, G.; Carbone, V.; Berrilli, F.; Caccin, B.; Pietropaolo, E.; Ermolli, I.; Florio, A. Bibcode: 1998MmSAI..69..651C Altcode: No abstract at ADS Title: Properties of solar granulation cells in quiet regions as derived from a time series of white light images Authors: Cauzzi, G.; Consolini, G.; Berrilli, F.; Smaldone, L. A.; Straus, T.; Bavassano, B.; Bruno, R.; Caccin, B.; Carbone, V.; Egidi, A.; Ermolli, I.; Florio, A.; Pietropaolo, E. Bibcode: 1998MmSAI..69..647C Altcode: No abstract at ADS Title: Recent results of the Italian solar research. Proceedings. Meeting, Roma (Italy), 18 - 20 Mar 1998. Authors: Ermolli, I.; Berrilli, F.; Caccin, B. Bibcode: 1998MmSAI..69..513E Altcode: Provided with new data from space missions, following topics were dealt with: solar interior and global structure, solar photosphere and chromosphere, solar corona, solar wind and interplanetary medium. Title: Preliminary results on solar photospheric MHD turbulence studied via signed measures. (Based on THEMIS/IPM observations.) Authors: Consolini, G.; Bruno, R.; Bavassano, B.; Carbone, V.; Mainella, G.; Berrilli, F.; Caccin, B.; Pietropaolo, E.; Ermolli, I.; Florio, A. Bibcode: 1998joso.proc..115C Altcode: In the present paper the autors report about the occurrence of sign-singularity in the solar photospheric MHD turbulence, using Dopplergrams provided during the past August 1997 by the Italian Panoramic Monochromator (IPM) at the THEMIS telescope (Tenerife). Title: Foreword Authors: Ermolli, I.; Berrilli, F.; Caccin, B. Bibcode: 1998MmSAI..69..519E Altcode: No abstract at ADS Title: Image acquisition system for the Italian Panoramic Monochromator of the THEMIS telescope. Authors: Berrilli, F.; Caccin, B.; Cantarano, S.; Egidi, A. Bibcode: 1997NCimC..20..967B Altcode: Describes the image acquisition system of the Italian Panoramic Monochromator which will be in operation at the focus F2 of the THEMIS solar telescope to acquire images of the Sun in the visible spectrum (between 420 and 700 nm) with a spectral resolving power of about 300000. The system consists of two CCD cameras (using either 512×512 or 1024×1024 square-pixel sensors) controlled and readout by dedicated electronics and a personal computer. The data transmission between the sensors and the computer is performed by means of an optical link. Title: The IPM-Italian Panoramic Monochromator operating at the THEMIS telescope. Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.; Berrilli, F.; Caccin, B.; Cantarano, S.; Egidi, A. Bibcode: 1997cpyt.conf..119C Altcode: From April 20, 1997 the Italian Panoramic Monochromator (henceforth IPM) will be the first operating mode of the THEMIS telescope. It basically consists of a Fabry-Perot interferometer mounted in tandem with an universal birefringent filter. The image acquisition system consists of two CCD cameras controlled and read-out by dedicated electronics and personal computers. One of these cameras acquires a simultaneous white light image for the application of off-line destretching procedures in order to reduce seeing effects. An optical link connects the CCD camera and the PCs while the handshaking and the data transfer between the PCs and the work station controlling the IPM is performed via LAN and IEE488 bus. Title: Search for Alfvénic fluctuations at the photosphere Authors: Bruno, R.; Bavassano, B.; Berrilli, F. Bibcode: 1997MmSAI..68..483B Altcode: No abstract at ADS Title: Time dependence of the chromospheric network properties. Authors: Berrilli, F.; Ermolli, I.; Florio, A.; Pietropaolo, E. Bibcode: 1997cpyt.conf..105B Altcode: Continuous sets of white-light and Ca II K line images are used to derive optimal proxy indices of the solar irradiance variation. In the framework of the RISE (Radiative inputs of the Sun to Earth) project the first PSPT (Precise Solar Photometric Telescope) telescope is operative at the Monte Carlo Observatory in Rome since February 1996. A sequence of PSPT Ca K line images obtained in a period of minimum solar activity (from July to November 1996) have been used to analyze the time dependence of the intensity, the morphology and the scaling properties of the network cells. Title: Investigating the Circumstellar Morphology of Herbig Ae/Be Stars Authors: Lorenzetti, D.; Nisini, B.; Pezzuto, S.; Strafella, F.; Berrilli, F. Bibcode: 1996rdfs.conf..191L Altcode: No abstract at ADS Title: The solar-image acquisition system at Tor Vergata University. Authors: Berrilli, F.; Cantarano, S.; Egidi, A. Bibcode: 1995NCimC..18..269B Altcode: Describes an image acquisition system realized as a part of an apparatus built in collaboration with the Arcetri Astrophysical Observatory in Florence designed to record high-spectral-resolution solar images in the visible part of the spectrum. The system is based on a 512×512 Thomson CCD type THX31159 and on a 486 CPU personal computer running under MS-DOS. The electronics for driving the sensor and for the amplification and conditioning of the video signal has been designed and built in the laboratory while the signal A/D conversion and image presentation is performed using commercial boards. Title: Circumstellar structures around Herbig Ae/Be stars Authors: Lorenzetti, D.; Nisini, B.; Berrilli, F.; Strafella, F. Bibcode: 1994ASPC...62..189L Altcode: 1994nesh.conf..189L No abstract at ADS Title: The solar CCD imaging system at Tor Vergata University Authors: Berrilli, F.; Caccin, B.; Cantrano, S.; Egidi, A.; Ermolli, I. Bibcode: 1993MmSAI..64..549B Altcode: No abstract at ADS Title: Panoramic monochromatic detector for the THEMIS telescope: acquisition and image processing system Authors: Cantarano, S.; Cerulli, R.; Berrilli, F.; Egidi, A. Bibcode: 1993MmSAI..64..768C Altcode: No abstract at ADS Title: First measurements of solar oscillations with the THEMIS panoramic monochromator Authors: Berrilli, F.; Caccin, B.; Cantrano, S.; Cavallini, F.; Ceppatelli, G.; Egidi, A.; Francia, P.; Pietropaolo, E.; Righini, A. Bibcode: 1993MmSAI..64..781B Altcode: No abstract at ADS Title: High-resolution spectroscopic imaging of the Sun with a Universal Birefringent filter and a Fabry-Perot interferometer. Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.; Berrilli, F.; Caccin, B.; Cantarano, S.; Egidi, A.; Francia, P.; Pietropaolo, E. Bibcode: 1992NCimC..15..509C Altcode: The authors describe an optical device consisting of a Universal Birefringent Filter and a Fabry-Perot interferometer used in tandem to obtain monochromatic images of the Sun in the visible spectrum (between 4200 and 7000 Å). They give an account of the preliminary results obtained by measuring the global velocity field on the solar photosphere. These results show that the instrument is well suited for global oscillation measurements. Title: A study of the solar atmosphere with high-resolution spectroscopic images: acquisition system. Authors: Berrilli, F.; Cantarano, S.; Egidi, A.; Magagna, A. Bibcode: 1992NCimC..15..519B Altcode: The authors describe the image acquisition system realized as a part of an experiment designed to record high-spectral-resolution solar images in the visible part of the spectrum. The system is based on a Charge Coupled Device Thomson THX31159. The electronics for driving the sensor and for the amplification and conditioning of the video signal has been designed and built in the laboratory, while a VME-bus-based computer has been used for the timing of operations, for the signal A/D conversion and for image presentation and storage. Title: Infrared Emission from Dust Structures Surrounding Herbig Ae/Be Stars Authors: Berrilli, F.; Corciulo, G.; Ingrosso, G.; Lorenzetti, D.; Nisini, B.; Strafella, F. Bibcode: 1992ApJ...398..254B Altcode: We present IR observations in J, H, K, L, M, and 8-13-micron bands of Herbig Ae/Be stars located in the Southern Hemisphere. Silicate features detected both in emission and in absorption indicate the presence of dust around these objects. A first analysis based on two-color diagrams, polarization, and luminosity suggests that the spherical geometry for the dust distribution is a more common feature, with respect to the flattened structure. An emission model in which the central object is surrounded by a circumstellar envelope of gas and dust is introduced and the continuum spectrum is computed taking into account radiative properties both of gas (free-free, free-bound, electron scattering) and dust. The numerical results, compared with the observations, suggest that anisotropic dust distributions are not necessarily required to account for the emitting properties of the circumstellar envelopes around Herbig Ae/Be stars. Title: Circumstellar Structures around Herbig Ae/be Stars. Authors: Berrilli, F.; Corciulo, G.; Ingrosso, G.; Lorenzetti, D.; Nisini, B.; Strafella, F. Bibcode: 1991sepa.conf..377B Altcode: 1991IAUCo.129..377B No abstract at ADS Title: IRAS observations of Herbig Ae/Be stars. Authors: Berrilli, F.; Ceccarelli, C.; Lorenzetti, D.; Nisini, B.; Saraceno, P.; Strafella, F. Bibcode: 1990NCimC..13..293B Altcode: The authors present a catalog of IRAS counterparts of the Herbig Ae/Be stars. They discuss the obtained spectral shapes from 1 to 100 μm, and correlating the IR excess and the reddening effect, positive indications of flat distributions of the cold dust can be derived. Title: Erratum - the Evolutionary Status of Young Stellar Mass Loss Driving Sources as Derived from IRAS Observations Authors: Berrilli, F.; Ceccarelli, C.; Liseau, R.; Saraceno, P.; Spinoglio, L. Bibcode: 1989MNRAS.239..255B Altcode: No abstract at ADS Title: The evolutionary status of young stellar mass loss driving sources asderived from IRAS observations. Authors: Berrilli, F.; Ceccarelli, C.; Liseau, R.; Lorenzetti, D.; Saraceno, P.; Spinoglio, L. Bibcode: 1989MNRAS.237....1B Altcode: A statistical analysis of the IRAS data for young stellar objects associated with mass outflows (Herbig-Haro objects and molecular outflows) is presented. Systematic differences are found between the observed far-infrared behavior and that predicted by a model describing the main accretion phase during the formation of low-mass stars. It is suggested that the low-mass outflow sources are at a later evolutionary stage and not truly protostellar. Title: The evolutionary status of young stellar mass loss driving sources as derived from IRAS observations Authors: Berrilli, F.; Ceccarelli, C.; Liseau, R.; Lorenzetti, D.; Saraceno, P.; Spinoglio, L. Bibcode: 1988STIN...8913386B Altcode: A statistical analysis of the IRAS data for young stellar objects associated with mass outflows (Herbig-Haro objects and molecular outflows) is presented. Systematic differences are found between the observed far IR behavior and that predicted by the model by Adams and Shu (1986) describing the main accretion phase during the formation of low mass stars. It is suggested that the low mass outflow sources are at a later evolutionary stage and not truly protostellar. The IRAS data permit an accurate derivation of the bolometric luminosities, which span over six orders of magnitude for the driving sources of the molecular outflows. From the observed luminosity function the mass function is mass function for the stars in the solar neighborhood, suggesting that heavy mass loss was an important phase during the formation of stars at all times in the history of the galaxy. Title: Multiband photometry (8-13 μm) of Herbig Ae/Be stars. Authors: Berrilli, F.; Lorenzetti, D.; Saraceno, P.; Strafella, F. Bibcode: 1987MNRAS.228..833B Altcode: New multifilter 8 - 13 μm observations of 14 Herbig Ae/Be stars are presented. Silicate features are found in emission or absorption; a simple model to fit the obtained data provides an evaluation of the dust shell temperature and of the optical depth τ10. These parameters are used both to define the circumstellar dust shell and to discuss the applicability of the free-free hypothesis to explain the near-infrared spectrum (J,H,K,L' and M). Title: IRAS observations of outflow exciting sources. Authors: Berrilli, F.; Ceccarelli, C.; Lorenzetti, D.; Saraceno, P.; Spinoglio, L. Bibcode: 1987MmSAI..58..191B Altcode: The authors used the IRAS data to study the statistical behaviour of young stellar objects characterized by the presence of strong mass loss, i.e. HH objects and CO emission exciting sources. Both classes of objects result to be surrounded by cold (T ≡ 50K) dust envelopes, whose IRAS colours systematically differ from those predicted by current protostar models. The bolometric luminosities of these exciting sources are distributed on two different classes whose luminosity values differ of a factor 103; the authors discuss the possibility that the two classes of objects differ for the central mass and/or for the presence of massive accreting disks. Title: Circumstellar environment of the Herbig Ae/Be stars Authors: Berrilli, F.; Lorenzetti, D.; Saraceno, P.; Strafella, F. Bibcode: 1987cpnc.conf..119B Altcode: No abstract at ADS Title: 62nd - 66th list of minima of eclipsing binaries. Authors: Boninsegna, R.; Clovin, J. -P.; Diethelm, R.; Doby, P.; Frangeul, M.; Germann, R.; Hevesi, Z.; Locher, K.; Marot, A.; Peter, H.; Poretti, E.; Remis, J.; Troispoux, G.; Behagle, M.; Le Borgne, J. -F.; Ralincourt, P.; Royer, A.; Seretti, A.; Squelard, J.; Zaccaria, N.; Travaglino, F.; Tuboly, V.; Berrilli, F.; Boninsegna, V.; Bouzin, B.; Cayla, P.; Le Saout, M.; Leydon, R.; Wabniz, S.; Buzzoni, A.; Kratochwill, R.; Lucentini, E.; Del Parigi, A.; Plasmati, C. Bibcode: 1976BBSAG..29....1B Altcode: No abstract at ADS