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Author name code: berrilli
ADS astronomy entries on 2022-09-14
author:"Berrilli, Francesco"
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Title: The Great Aurora of 4 February 1872 observed by Angelo Secchi
in Rome
Authors: Berrilli, Francesco; Giovannelli, Luca
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.
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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
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.
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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
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.
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Title: Scaling properties of magnetic field fluctuations in the
quiet Sun
Authors: Giannattasio, F.; Consolini, G.; Berrilli, F.; De Michelis, P.
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. <BR /> 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. <BR /> 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. <BR />
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.
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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.
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.
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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.
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.
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Title: Prediction of Sunspot and Plage Coverage for Solar Cycle 25
Authors: Penza, Valentina; Berrilli, Francesco; Bertello, Luca;
Cantoresi, Matteo; Criscuoli, Serena
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.
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Title: The star-planet interaction by combining asteroseismic and
space weather techniques
Authors: Reda, Raffaele; Giovannelli, Luca; Berrilli, Francesco;
Di Mauro, Maria Pia
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.
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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
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.
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Title: Stellar Turbulent Convection: The Multiscale Nature of the
Solar Magnetic Signature
Authors: Scardigli, Stefano; Berrilli, Francesco; Del Moro, Dario;
Giovannelli, Luca
2021Atmos..12..938S Altcode:
No abstract at ADS
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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.
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.
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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
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.
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Title: Three-dimensional Climate Simulations for the Detectability
of Proxima Centauri b
Authors: Galuzzo, Daniele; Cagnazzo, Chiara; Berrilli, Francesco;
Fierli, Federico; Giovannelli, Luca
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.
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Title: Long-term correlations in solar proxies and solar wind
parameters
Authors: Reda, Raffaele; Alberti, Tommaso; Berrilli, Francesco;
Giobbi, Piermarco; Giovannelli, Luca; Penza, Valentina
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.
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Title: A new method for detecting solar atmospheric gravity waves
Authors: Calchetti, Daniele; Jefferies, Stuart M.; Fleck, Bernhard;
Berrilli, Francesco; Shcherbik, Dmitriy V.
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. <P />This article is part of
the Theo Murphy meeting issue `High-resolution wave dynamics in the
lower solar atmosphere'.
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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.
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.
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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
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.
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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
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=m<SUP>2</SUP>, 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.
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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
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.
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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
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.
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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
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 D<SUB>2</SUB> line) and 769.9 nm
(K D<SUB>1</SUB> 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
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
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.
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.
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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.
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
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. <P />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. <P />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.
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
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.
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
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.
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
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
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
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
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
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.
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
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
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
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
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
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
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.
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.
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.
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.
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.
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.
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
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
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
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
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
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.
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. <BR /> 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. <BR /> 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. <BR /> 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.
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
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
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
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
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.
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.
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.
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
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.
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.
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
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.
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
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
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.
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.
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
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.
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. <BR /> 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. <BR /> 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. <BR /> 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. <BR /> 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. <P />A
movie associated to Fig. 4 is available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201525887/olm">http://www.aanda.org</A>
---------------------------------------------------------
Title: The Sun: the Earth light source
Authors: Berrilli, Francesco; Giovannelli, Luca; Del Moro, Dario;
Piazzesi, Roberto; Catena, Liu` Maria; Amicucci, Giordano; Vittorio,
Nicola
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.
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. <BR /> 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. <BR /> 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. <BR />
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. <BR /> 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
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
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.
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 r<SUB>0</SUB>. 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.
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.
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.
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<SUP>-4</SUP>) 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
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.
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)<SUP>2</SUP>rangvpropτ<SUP>γ</SUP> (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
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
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. <BR /> 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. <BR /> 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. <BR />
Results: We present in this work an analysis of the ALTEA data measured
during the March 7th, 2012 solar event, produced by NOAA AR11429. <BR
/> 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.
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.
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.
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. <BR /> 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. <BR /> 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. <BR />
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. <BR />
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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: <BR /> · Radiative and dynamical
properties of Photospheric Bright Points versus their magnetic field
concentration. <BR /> · Close up analysis of magnetic, velocity and
temperature field in a solar pore. <BR /> · 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.
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.
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.
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. <BR /> 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. <BR /> 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. <BR />
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. <P />Appendices A and B, and a movie are available in electronic
form at <A href="http://www.aanda.org">http://www.aanda.org</A>
---------------------------------------------------------
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.
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.
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
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
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.
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.
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.
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.
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.
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.
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.
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.
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 arcsec<SUP>2</SUP> pixel scale), with
0.1% polarimetric accuracy. The analysis of a 60×60 pxls<SUP>2</SUP>
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.
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. <P />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.
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. <BR /> Aims: Relations
between the magnetic field components, line-of-sight velocities,
and horizontal motions in and around a large pore (D<SUB>eff</SUB> =
8”.5) are analysed to provide observational constraints on theoretical
models and numerical simulations. <BR /> 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. <BR /> 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 B<SUB>hor</SUB> is
more extended than the vertical component B<SUB>z</SUB>. The temperature
linearly decreases with increasing B<SUB>z</SUB>, by about - 300 K
kG<SUP>-1</SUP> in the photosphere and - 800 K kG<SUP>-1</SUP> in the
umbra. The temperature contrast of granulation increases with increasing
magnetic field strength and is then suppressed for B<SUB>z</SUB> >
1200 G. Granular upflows dominate in regions with B<SUB>z</SUB> <
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 B<SUB>hor</SUB>
> 1000 G. Horizontal motions of granules start to be damped for
B<SUB>z</SUB> > 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.
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.
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.
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
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
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.
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 10<SUP>3</SUP> 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. <P />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.
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.
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.
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.
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.
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<SUP>-3</SUP> the continuum intensity level. We focus on the
correlation which emerges between the G-band bright feature brightness
and magnetic filling factor of ~10<SUP>3</SUP> 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.
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
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.
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.
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.
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.
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
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.
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.
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
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
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 10<SUP>5</SUP>
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.
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.
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.
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<SUP>-3</SUP> 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.
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.
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). <BR />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. <BR />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. <BR />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. <BR />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.
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
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.
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.
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.
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. <BR />Aims: We study the structure
of a solar pore (AR10812) with a light bridge. <BR />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. <BR />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<SUP>-1</SUP>, and is surrounded by an annular downflow structure
with an average velocity of about -300 m s<SUP>-1</SUP> 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<SUP>-1</SUP>, flanked by a
downflow of about 150 m s<SUP>-1</SUP> 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.
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. <BR />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. <BR />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. <BR />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 < B<SUP>2</SUP> ><SUP>1/2</SUP>≃ 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. <BR
/>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.
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. <P
/>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.
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. <P />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. <P />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. <P />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. <P />ADAHELI also carries MIOS, a millimeter wavelengths
radiometer operating at around 90 GHz for flare detection. <P />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. <P />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.
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:
<P />1. SOT/SP instrument aboard the HINODE satellite. <P />2. IBIS
in spectropolarimetric mode imaging, supported by simultaneous white
light and G-band images, for blind deconvolution reconstruction. <P
/>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.
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.
2008ESPM...12.2.75S Altcode:
Time delay error and integration time effects play a crucial role in
Solar Adaptive Optics systems. <P />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. <P />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. <P />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. <P />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. <P />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.
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
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.
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.
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.
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. <BR />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. <BR />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.
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.
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.
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.
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.
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
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.
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.
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.
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.
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.
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.
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.
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.
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.
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,
g<SUB>2</SUB>(r), to segmented features in the solar fields. We
compare the computed g<SUB>2</SUB>(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.
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.
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.
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<SUP>-4</SUP>.
---------------------------------------------------------
Title: Characterization of supergranular features via topological
measures
Authors: Berrilli, F.; del Moro, D.; Giordano, S.; Consolini, G.;
Kosovichev, A.
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
g<SUB>2</SUB>(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.
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.
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.
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 g<SUB>2</SUB>(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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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<SUP>-4</SUP> at the activity minimum. Besides,
we estimated a change of the network contribution to TSI of order 3x
10<SUP>-4</SUP> 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.
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.
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 <SUB>k</SUB> 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.
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.
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.
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
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.
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: MgIb<SUB>2</SUB> Bright Features in the Solar Photosphere
Authors: Berrilli, F.; Bruno, R.; Consolini, G.; Florio, A.;
Pietropaolo, E.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
1997NCimC..20..967B Altcode:
Describes the image acquisition system of the Italian Panoramic
Monochromator which will be in operation at the focus F<SUB>2</SUB>
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.
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.
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.
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.
1996rdfs.conf..191L Altcode:
No abstract at ADS
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Title: The solar-image acquisition system at Tor Vergata University.
Authors: Berrilli, F.; Cantarano, S.; Egidi, A.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 τ<SUB>10</SUB>. 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.
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 10<SUP>3</SUP>; 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.
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.
1976BBSAG..29....1B Altcode:
No abstract at ADS
