Author name code: chiuderi
ADS astronomy entries on 2022-09-14
author:"Chiuderi, Claudio" 
------------------------------------------------------------------------  

Title: Basics of Plasma Astrophysics
Authors: Chiuderi, C.; Velli, M.
Bibcode: 2015bps..book.....C
Altcode:
  No abstract at ADS

Title: A new fluid scheme for weakly collisional plasmas: 2. The
    case of solar wind
Authors: Pietrini, P.; Torricelli-Ciamponi, G.; Chiuderi, C.
Bibcode: 2012JGRA..11712105P
Altcode:
  Chiuderi et al. (2011) (paper 1) investigated the possibility of
  extending to weakly collisional plasmas the new fluid scheme recently
  developed by Chen et al. (2000) for neutral gases. Paper 1 established
  the conditions under which such an extension is feasible and identified
  the solar wind as a good candidate to test the new theory. Such a test
  is performed in the present paper, where we actually build a model for
  the fast solar wind and compare it with the available data. We define
  the basic assumptions adopted: steadiness, spherical symmetry, and
  neglect of magnetic field and of minor ions. We limit our treatment to
  the range 2-215 R<SUB>⊙</SUB>to cover the details of the transition
  from collisional to collisionless regimes, excluding the low corona
  and the chromosphere that appear to be far too complex to be described
  by our simple model. We present a detailed discussion concerning
  the choice of the parameters and boundary conditions entering the
  model. We then proceed to the actual construction of the model, whose
  main merit lies in its simplicity: it is a two-fluid model capable
  of accounting for both viscosity and thermal conduction, in spite of
  the very limited number of equations to be solved. We then critically
  compare our results with the observations and with other recent solar
  wind models. The level of agreement with the data is quite satisfactory
  and is comparable with that obtained by more sophisticated models.

Title: A new fluid scheme for weakly collisional plasmas: 1. General
    theory
Authors: Chiuderi, C.; Pietrini, P.; Torricelli-Ciamponi, G.
Bibcode: 2011JGRA..116.4107C
Altcode:
  We present a new approach to the study of two-fluid hydrodynamics of
  weakly collisional plasma systems, such as those frequently encountered
  in the astrophysical context. Our starting point is the novel procedure
  developed in past years by Chen, Rao, and Spiegel (CRS) for the
  fluid description of semicollisional neutral monoatomic gases. The
  new system of fluid equations that include viscous and conductive
  effects has been successfully tested. However, the extension of such
  a procedure to plasmas is not a straightforward one. We have to deal
  with (at least) two components, with vastly different values of the
  masses, and the nature of collisions between charged particles is
  substantially different from the neutral particle case. We perform a
  preliminary careful examination of the basic requirements of the CRS
  method and identify the conditions under which an extension of such
  method is indeed possible. We then derive the system of fluid equations
  appropriate to the description of a weakly collisional two-component
  plasma in the new scheme and discuss the differences with respect to
  the more familiar Navier-Stokes approach. This paper is therefore of
  a general theoretical nature. However, we also point out that solar
  wind is a good testing ground for the newly derived system of fluid
  equations. This application will be the subject of a subsequent paper.

Title: Solar MHD: An Introduction
Authors: Chiuderi, C.; Velli, M.
Bibcode: 2009LNP...778...45C
Altcode:
  The Universe is filled by plasmas. In fact, it can be reasonably
  estimated that more than 95% of (standard) cosmic matter is found in the
  plasma state. Given this basic fact, it is apparent that plasma physics
  is the basic tool to understand the mechanisms that are at work in
  the astrophysical context and to interpret the observations. The Earth
  represents a notable exception as far as the presence of natural plasmas
  is concerned, a lucky circumstance for living beings. In practice,
  terrestrial plasmas are almost exclusively produced during electrical
  discharges, such as lightning. If plasmas are almost absent on Earth
  and in the low-altitude atmosphere, they start to be the dominant
  state of matter immediately beyond the ionosphere, the magnetosphere,
  and the whole heliosphere that includes the entire solar system made
  up of plasmas. The Sun, like the other stars, is made up of ionized
  gas almost everywhere.

Title: Effect of suprathermal particles on the quiet Sun radio
    emission
Authors: Chiuderi, C.; Chiuderi Drago, F.
Bibcode: 2004A&A...422..331C
Altcode:
  The bremsstrahlung emissivity and absorption coefficient in the
  radiofrequency range are derived under the assumption that the electron
  population is not purely thermal, but presents a tail of high energy
  particles. This population is approximated by a two-component Maxwellian
  distribution and by the kappa-functions of different (integer) index. It
  is shown that, if the temperature ratio of the two Maxwellians is larger
  than 10, the absorption coefficient and the effective temperature
  (the quantities entering the radio transfer equation) depend only on
  the fraction R of particles in the highest temperature Maxwellian. In
  the case of kappa-functions the above quantities depend on the index
  n of the functions. <P />The microwave radio spectrum is computed
  for different values of R and for 3 ≤ n ≤ 6, finding, in all
  cases, brightness temperatures lower than those computed with a pure
  thermal distribution. This could explain some inconsistencies found
  between radio and EUV observations. <P />Appendix is only available
  in electronic form at http://www.edpsciences.org

Title: Effect of suprathermal particles on the quiet sun radio
    emission
Authors: Chiuderi, C.; Chiuderi Drago, F.
Bibcode: 2004cosp...35..289C
Altcode: 2004cosp.meet..289C
  The bremsstrahlung emissivity and absorption coefficient in the
  radiofrequencies range are derived in the assumption that the
  electron population is not purely thermal, but presents a tail of high
  energy particles. This population is approximated by a bi-Maxwellian
  distribution and by kappa-functions of different (integer) index. It is
  shown that, if the temperature ratio of the two Maxwellians is larger
  than 10, the absorption coefficient and the effective temperature
  (the quantities entering the radio transfer equation) depend only on
  the fraction R of particles in the highest temperature maxwellian. In
  case of kappa-functions the above qunatities depend on the index
  n of the functions. The microwave radio spectrum is computed for
  different values of R and for 3 ≤ n ≤ 6, finding, in all cases,
  brightness temperatures lower than those computed with a pure thermal
  distribution. This fact could explain some inconsistencies found
  between radio and EUV observations.

Title: Effect of Superthermal Particles in the Quiet Sun Radio
    Emission
Authors: Chiuderi, C.; Chiuderi Drago, F.
Bibcode: 2003MmSAI..74..695C
Altcode:
  The bremsstrahlung emissivity and absorption coefficient, in the
  radiofrequencies range, are derived in the assumption that the
  electron population is not purely thermal, but presents a tail of high
  energy particles. This population is approximated by a bi-Maxwellian
  distribution. It is shown that, if the temperature ratio of the two
  Maxwellians is larger than 10, the absorption coefficient and the
  effective temperature depend only on the fraction R of particles in
  the highest temperature Maxwellian. The microwave radio spectrum is
  computed for some values of R, finding brightness temperatures lower
  than those computed with a pure thermal distribution. This fact could
  explain some inconsistencies found between radio and EUV observations.

Title: The World Space Observatory Project WSO/UV
Authors: Pagano, I.; Rodonò, M.; Bonanno, G.; Buson, L.; Cassatella,
   A.; De Martino, D.; Wamsteker, W.; Shustov, B.; Barstow, M.; Brosch,
   N.; Fu-Zhen, Cheng; Dennefeld, M.; Gomez de Castro, A. I.; Kappelmann,
   N.; Sahade, J.; Van der Hucht, K.; Solheim, J. -E.; Haubold, H.;
   Altamore, A.; Andretta, V.; Badiali, M.; Becciani, U.; Busà, I.;
   Cappellaro, E.; Cardini, D.; Catalano, S.; Castellani, V.; Chiaberge,
   M.; Chieffi, A; Chiuderi, C.; Cosentino, R.; Cremonese, G.; Cutispoto,
   G.; Falomo, R.; Ferrini, F.; Franchini, M.; Frasca, A.; Giovannelli,
   F.; Gori, L.; Gomez, M.; Hack, M.; Lanza, A. F.; Lanzafame, A.;
   Malagnini, M. L.; Marilli, E.; Marziani, P.; Matteucci, F.; Morossi,
   C.; Munari, U.; Pace, E.; Panagia, N.; Pasinetti, L.; Piotto, G.;
   Polcaro, F.; Radovich, M.; Ragaini, S.; Rifatto, A.; Rossi, C.;
   Scuderi, S.; Selvelli, P.; Silvotti, R. L. Terranegra5, M. Turatto3,
   M. Uslenghi22, R. Viotti4
Bibcode: 2003MSAIS...3..327P
Altcode: 2003astro.ph..6554P
  The World Space Observatory Project is a new space mission concept,
  grown out the needs of the Astronomical community to have access to
  the part of the electromagnetic spectrum where all known physics can be
  studied on all possible time scales: the Ultraviolet range. The physical
  diagnostics in this domain supply a richness of new experimental
  data unmatched by any other wavelength range, for the studies of the
  Universe. As WSO/UV has been driven by the needs of scientists from
  many different countries, a new implementation model was needed to
  bring the World Space Observatory to reality. The WSO/UV consists of a
  single Ultraviolet Telescope in orbit, incorporating a primary mirror
  of 1.7 m diameter feeding a UV spectrograph and UV Imagers.

Title: Nonlinear processes in heliospheric plasma: models and
    observations
Authors: Velli, M.; Einaudi, G.; Chiuderi, C.; Veltri, P. L.;
   MM02242342 project Team; Betta, R.; Londrillo, P.; Rappazzo, F.;
   Del Zanna, L.; Landi, S.; Malara, F.; Carbone, V.; Zimbardo, G.;
   Primavera, L.; Greco, A.; Sorriso-Valvo, L.; Pommois, P.; Lepreti, F.
Bibcode: 2003MmSAI..74..425V
Altcode:
  We present the scientific objectives of the research project `Nonlinear
  processes in heliospheric plasma: models and observations', co-financed
  by the Italian Ministry for Universities and Scientific Research, as
  well as a summary of some of the results obtained. The objective of the
  proposal was a detailed study of the nonlinear and dissipation-scale
  dynamics of heliospheric plasmas. The project focused on the study of
  wave propagation and properties of turbulence at the various scales,
  from the macroscopic scales of the solar wind, down to the microscopic
  scales of magnetic reconnection and turbulence dissipation, in its
  two aspects of evolutionary internal dynamics, and its effects on the
  transport of energetic particles of both heliospheric and extra-solar
  origins (cosmic rays, interstellar neutrals ionized in the solar wind
  as pickup ions).

Title: Resistivity Independent Alfven Waves Dissipation
Authors: Chiuderi, C.; Califano, F.
Bibcode: 1999ESASP.446..235C
Altcode: 1999soho....8..235C
  The heating of high temperature plasmas by MHD waves is one of the
  most interesting and challenging problems of plasma physics especially
  when the energy is injected into the system at length scales much
  larger than the dissipative ones. It has been conjectured that in
  2-D MHD systems the possibility exist of establishing a state in
  which energy is dissipated at a rate that is independent of the ohmic
  resistivity and that the time needed to reach such a state is finite and
  independent of resistivity as well. We study the nonlinear interaction
  of long-wavelength, small amplitude perturbations with an inhomogeneous
  magnetic field showing that energy is transferred to the fluctuations
  from the background equilibrium. In the case of an isolated system,
  the free energy initially stored in the equilibrium would decrease
  and the field would tend to become homogeneous. To model the process
  of energy injection into the system, we force the large scale field to
  maintain its initial profile. In these circumstances, we prove that it
  is actually possible after a finite time, independent of the dissipative
  mechanism, to generate a well developed 2-D MHD turbulent state where
  the dissipation rate does not depend on the Lundquist number, at least
  for values of the order of a few thousands. To our knowledge, this is
  the first time in which the existence of the conjectured resistivity
  independent dissipation has been explicitly demonstrated.

Title: Resistivity-independent dissipation of magnetohydrodynamic
    waves in an inhomogeneous plasma
Authors: Califano, F.; Chiuderi, C.
Bibcode: 1999PhRvE..60.4701C
Altcode:
  The heating of high temperature plasmas by magnetohydrodynamic
  (MHD) waves is one of the most interesting and challenging problems
  of plasma physics especially when the energy is injected into the
  system at length scales much larger than the dissipative ones. It has
  been conjectured that in two-dimensional MHD systems the possibility
  exists of establishing a state in which energy is dissipated at a
  rate that is independent of the Ohmic resistivity and that the time
  needed to reach such a state is finite and independent of resistivity
  as well. In this paper we prove that this is actually possible as
  a result of the nonlinear interaction of long-wavelength, ``small''
  amplitude perturbations with a constant, inhomogeneous magnetic field,
  at least in the relatively moderate Lundquist number (magnetic Reynolds)
  range 100&lt;=S&lt;=3200.

Title: A New Model for Gas Excitation in the Beam of Stellar Jets
Authors: Bacciotti, F.; Pouquet, A.; Chiuderi, C.
Bibcode: 1998ajop.conf..239B
Altcode:
  No abstract at ADS

Title: Optical Emission in the Beam of Stellar Jets: A Possible
    Mechanism
Authors: Bacciotti, F.; Chiuderi, C.; Pouquet, A.
Bibcode: 1997ApJ...478..594B
Altcode:
  We propose a mechanism for the optical emission observed in the
  beam section of stellar jets based on the stability properties
  of circularly polarized Alfvén waves propagating in the partially
  ionized medium filling the jet's channel. We first derive the relevant
  magnetohydrodynamic equations, which include the Hall term for such
  a partially ionized medium, a term which give rise to dispersive
  effects. Quasi-equipartition of thermal and magnetic energies
  is assumed, and the model is developed in the one-dimensional
  approximation but keeping the three components of the vectorial
  fields. Mild compressions or very weak shocks occur in the flow when
  instabilities develop, depending on the relative sign of the angular
  momentum of the underlying accretion disk and the external magnetic
  field. Simulations performed under quite general conditions show that
  the temperature/density perturbations associated with the instability
  are consistent with the average luminosity contrast observed in the
  jet's beam between bright knots and interknot regions.

Title: Concluding remarks: solar physics and the advancement of
    physics
Authors: Chiuderi, C.
Bibcode: 1997MmSAI..68..449C
Altcode:
  No abstract at ADS

Title: A mechanism for the optical emission of stellar jets
Authors: Chiuderi, Claudio; Bacciotti, Francesca; Pouquet, Annick
Bibcode: 1997IAUS..182P..79C
Altcode:
  A mechanism for the optical emission of stellar jets is proposed,
  based on the stability properties of circularly polarized Alfven waves
  propagating in the partially ionized medium filling the jet channel. We
  adopt a MHD description including the Hall term, as appropriate for
  such a medium. Quasi-equipartition of thermal and magnetic energies
  is assumed. Shock-like features appear in the flow when instabilities
  develop, depending on the alignment of the angular momentum vector of
  the accretion disk along or against the background magnetic field. We
  show that the proposed mechanism is capable of reproducing the observed
  luminosity contrast between bright knots and interknot regions.

Title: Induced Deposition of Magnetic Energy in the Solar Corona
Authors: Einaudi, Giorgio; Califano, Francesco; Chiuderi, Claudio
Bibcode: 1996ApJ...472..853E
Altcode:
  In this paper a numerical study of the propagation and dissipation
  properties of magnetohydrodynamic waves in an incompressible magnetized
  plasma is presented. The magnetic field is assumed to be unidirectional,
  but its magnitude varies in a direction perpendicular to the field. The
  analysis concerns both linear and nonlinear waves. The main findings are
  the following. <P />Among the waves whose amplitude never exceeds the
  linear limit, short-wavelength waves dissipate more efficiently than
  those of long wavelength. The dissipated energy is at most the energy
  initially injected into the system in the form of waves, the background
  magnetic field remaining unaltered. When the initial amplitude is
  significantly increased from very small values, but remains still
  substantially lower than the background field, a nonlinear cascade is
  excited and dissipation is greatly enhanced in the long- wavelength
  limit. The dissipated energy in this case exceeds that contained in
  the waves initially injected into the system, which shows that also
  part of the unperturbed field is actually dissipated. <P />A second
  important point concerns the formation of localized current sheets
  in a finite time as a result of the propagation of the waves. Such
  current sheets are formed in a nonlinear process triggered by the
  same mechanism responsible for the formation of linear resonant normal
  modes. The dissipation rate of such modes is known to be independent
  of the Reynolds number. By analogy, it is conjectured that the time of
  formation of current sheets might not depend on the magnetic Reynolds
  number.

Title: Exact solutions for symmetric magnetohydrodynamic equilibria
    with mass flow.
Authors: Del Zanna, L.; Chiuderi, C.
Bibcode: 1996A&A...310..341D
Altcode:
  In this paper the problem of ideal magnetohydrodynamic equilibria with
  mass flow is treated. Under the assumption of general symmetry (i.e. one
  ignorable spatial coordinate) we derive a generalized Grad-Shafranov
  equation in an unspecified curvilinear coordinate system. If
  incompressibility is assumed an elliptical equation is derived and a
  new, totally analytical method of solution is proposed. This is based
  on a particular self-similar separation of the variables in the unknown
  flux function and leads to an ordinary, non-linear differential equation
  for the profile of the magnetic and flow surfaces. Three novel classes
  of solutions are derived in different geometries, all being flexible
  (they contain a minimum of three free functions) and regular, which
  makes them suitable for astrophysical applications. These are flows
  in magnetic flux tubes with non-circular section, flows in magnetic
  arcades above the solar surface and collimated, axisymmetric outflows.

Title: Theories of Coronal Heating (Invited)
Authors: Chiuderi, Claudio
Bibcode: 1996ASPC..111...69C
Altcode: 1997ASPC..111...69C
  This paper reviews the most recent trends in the theory of coronal
  heating. It is argued that the corona does most likely find itself
  in a fully developed turbulent state. The turbulence is the direct
  consequence of the random photospheric motions that stress the
  footpoints of magnetic field lines. Although the details of the
  propagation of energy from the photosphere to the corona could depend
  on the frequency of the driving motions, in all cases the key feature
  to explain coronal heating seems to be the formation and disruption of
  localized current sheets. This suggests a statistical approach to the
  theory of coronal heating as well as a possible link between heating
  and flares.

Title: Stellar Jets: Spectral Diagnostics and Fluidodynamic Models
Authors: Bacciotti, F.; Chiuderi, C.; Hirth, G.; Natta, A.; Oliva, E.
Bibcode: 1996LNP...465..329B
Altcode: 1996doay.conf..329B
  We present a non-standard, straightforward procedure for a
  model-independent determination of crucial physical parameters of the
  linear section of stellar jets, such as the hydrogen ionization fraction
  x and the temperature T <SUB> e </SUB> of the emitting gas. The method
  can be easily applied to every Herbig-Haro jet for which the brightest
  red lines have been measured, even if the lines are not calibrated and
  the ratios are not corrected for reddening. In the cases of HH 34 and
  HH 111 we find x∼0.1 and T <SUB>e</SUB>∼6000. The momentum rates
  evaluated with the derived total number densities (N∼10<SUP>4</SUP>
  cm<SUP>-3</SUP>) give strong support to the picture in which the
  luminous jet is only the fastest and most ionized component of a
  wider neutral flow that, in turn, has the capability of accelerating
  a molecular outflow. The ionization fraction cannot be explained in
  terms of equilibrium processes reflecting the local physical conditions
  of the medium, however the recombination length scales turn out to be
  comparable to the linear extension of the most luminous part of the
  jets: the observed degree of ionization is most likely the remnant of
  the heating and the excitation occurred in the initial accelerating
  region. This picture is supported by our diagnostics of RW Aur's
  optical jet, for which spatially resolved spectra have been taken:
  in this case the ionization fraction (around 10% again) is found to
  decrease slowly with distance from the star.

Title: Plasma Astrophysics
Authors: Chiuderi, Claudio; Einaudi, Giorgio
Bibcode: 1996LNP...468.....C
Altcode: 1996plas.conf.....C
  The book contains the notes of the lectures presented by outstanding
  experts at the 7th EADN School on plasma astrophysics. It is an
  up-to-date review of a number of basic topics in the physics of cosmic
  plasmas. The subject is treated both from a theoretical point of view
  and from that of the observational and diagnostic tools that provide
  us with the physically relevant data. The reader will have at hands a
  comprehensive and rather complete presentation of the subject, thanks
  also to the parallel development of the theoretical and experimental
  aspects. The book addresses graduate students and researchers in
  different areas who want to have a rapid and up-to-date introduction
  to this subject.

Title: Stellar Jets: Spectral Diagnostics and Fluidodynamic Models
Authors: Bacciotti, F.; Chiuderi, C.; Hirth, G.; Natta, A.; Oliva, E.
Bibcode: 1996LNP...465E.781B
Altcode:
  No abstract at ADS

Title: The structure of optical stellar jets: a phenomenological
    analysis.
Authors: Bacciotti, F.; Chiuderi, C.; Oliva, E.
Bibcode: 1995A&A...296..185B
Altcode:
  In this paper we discuss the possible mechanisms of formation ot
  the nodular structure of Herbig-Haro jets. The available spectral
  observations of the linear jet section in the HH 34 and the HH 111
  complexes are reviewed, in order to diagnostic the temperature and
  ionization state of the emitting material in a way as model-independent
  as possible. The values we find by means of an original although
  straightforward diagnostic procedure (T~6000K, x=n_H^+^_/n_H_~0.1, in
  both cases), are similar to those empirically determined by Bruegel
  et al. (1981) and Boehm &amp; Solf (1990) for the compact object HH
  7. Our results lead to a value of the momentum rate in these flows
  comparable to the rates observed in high-speed neutral winds (Lizano
  et al. 1988), giving support to the view according to which the bright
  optical jet actually identifies the axial portion of the neutral flow,
  and marks the location where the matter attains its maximum velocity
  and an observable amount of ionization. The ionization derived from
  the observations is likely to be a remnant of the heating and the
  excitation occurred in the accelerating region, where the wind is
  probably focused by the passage through a nozzle. The recombination
  time scale appropriate for the rather low electron densities in the
  jet is found to be close to the crossing time of the visible portion
  of the jet. Combining kinematical and energetic considerations we show
  that physical conditions consistent with the observed jet's emission
  can be obtained through "soft" compressions of the central portion of
  the flow, caused by 'damped' Kelvin-Helmoltz instabilities generated at
  the jet-ambient contact discontinuity. These compressions concentrate
  in smaller volumes the already available internal energy that is
  eventually radiated in optical and IR lines, unlike the weak shocks
  that actually increase the internal energy content by transforming the
  bulk kinetic energy into thermal random motions. A picture of this kind
  seems capable of resolving the long-standing problem of conciling the
  high supersonic velocity of the ionized material and the low excitation
  nature of the emission, and, at the same time, provides a very natural
  explanation for a number of observational constraints, among which the
  increase of the [SII]/Hα ratio along the jet and the disappearance
  of the optical emission after a characteristic scale length.

Title: Normal modes of a resistive nonuniform plasma
Authors: Chiuderi, C.; Califano, F.
Bibcode: 1994R&QE...37..355C
Altcode:
  The propagation and dissipation properties of magnetohydrodynamic
  waves in a nonuniform, highlyconducting plasma, is investigated with a
  normal mode approach. The interaction between the perturbation and the
  non-uniform supporting medium is analyzed as the main mechanism able
  to produce the small scale spatial structure necessary to dissipate
  efficiently the wave energy. Two fundamental classes of modes are
  found, characterized by their resistive or ideal asymptotic behavior;
  the damping rates are shown to be orders of magnitude larger than those
  obtained when the plasma is perfectly homogeneous, and an application
  to the problem of solar coronal heating is discussed.

Title: Coronal heating and solar activity: The role of waves
Authors: Einaudi, G.; Chiuderi, C.; Califano, F.
Bibcode: 1993AdSpR..13i..85E
Altcode: 1993AdSpR..13...85E
  Coronal heating and solar activity are manifestations of the complex
  interaction between the magnetic field and the photospheric plasma
  motions. As a result of such an interaction magnetohydrodynamic
  waves are generated: their dissipation may provide the basic physical
  mechanism to heat the corona. This paper describes the present status of
  knowledge of the physics underlying the dissipation of MHD waves. After
  having stressed the importance of the formation of small spatial scales
  for achieving an efficient dissipation, we review the theory of linear
  MHD waves in nonuniform media based on a normal mode approach. We then
  present the results of some recent numerical experiments and interpret
  them in the framework of the theory of MHD turbulence. A plan of future
  work will also be presented.

Title: Keys to understanding the corona.
Authors: Chiuderi, C.
Bibcode: 1993ESASP1157...25C
Altcode: 1993srfs.book...25C
  The theoretical understanding of the solar corona involves such
  different phenomena as the coronal heating and the occurrence of
  flares. It is argued that all of these phenomena could be seen as
  a manifestation of the same basic physics, the differences being a
  question of coherence. The theoretical work needed to support this view
  and its possible impact on future observational strategies are outlined.

Title: LY-A-CO-PO (LY α coronograph/polarimeter): an instrument to
    measure coronal magnetic fields
Authors: Fineschi, S.; Chiuderi, C.; Poletto, G.; Hoover, R. B.;
   Walker, A. B. C., Jr.
Bibcode: 1993MmSAI..64..441F
Altcode:
  No abstract at ADS

Title: New Exact Solutions for Magneto-Hydrodynamic Flows and Their
    Application to Stellar Jets
Authors: Bacciotti, F.; Chiuderi, C.
Bibcode: 1993ASSL..186..357B
Altcode: 1993sjbo.conf..357B
  No abstract at ADS

Title: Incompressible Disturbances in Nonuniform Media: Formation
    of Small Scales
Authors: Malara, Francesco; Veltri, Pierluigi; Chiuderi, Claudio;
   Einaudi, Giorgio
Bibcode: 1992ApJ...396..297M
Altcode:
  The study proposes a phenomenological interpretation of the mechanism
  of the formation of small scales during the propagation of an MHD
  wave where only z(+) fluctuations are excited. The nonlinear effects
  are shown to be negligible when the initial disturbance travels in
  the direction of the background magnetic field and its wavelength is
  comparable to the nonuniformity scale length. It is shown that the
  interaction between the perturbation and the inhomogeneous background
  has two effects: the oscillations of neighboring field lines become
  rapidly out of phase, producing small scales in the direction of
  nonuniformity, and the pressure gradients caused by the perturbation
  have the tendency to concentrate energy in the neighborhood of the point
  where the wave frequency resonates with the local Alfven frequency,
  with a subsequent local creation of small scales.

Title: Nonresonant Resistive Dissipation of Compressible
    Magnetohydrodynamic Waves
Authors: Califano, Francesco; Chiuderi, Claudio; Einaudi, Giorgio
Bibcode: 1992ApJ...390..560C
Altcode:
  The effect of compressibility on the propagation and resistive
  dissipation properties of magnetohydrodynamic waves in nonuniform media
  is studied by using a normal mode analysis. The paper concentrates on
  wave models for which the resistivity acts over the entire system,
  thus excluding localized resonant absorption. The wave modes in
  nonhomogeneous situations are identified in term of their familiar
  homogeneous counterparts and it is shown that only the shear Alfven
  and slow magnetosonic modes survive in the resistive regime. The most
  promising heating agents in the astrophysical context are shown to be
  the shear Alfven waves that behave almost incompressibly.

Title: Energy Balance in the Prominence / Corona Transition Region
Authors: Chiuderi, C.; Chiuderi Drago, F.
Bibcode: 1991SoPh..132...81C
Altcode:
  The prominence-corona transition region can be observed both at UV and
  radio wavelengths. The physical parameters needed to explain one set
  of observations are, however, in disagreement with those consistent
  with the other one. A solution of the problem is proposed, based on
  the proper consideration of the dependence of the thermal conduction
  on the angle between the magnetic field and the direction of the local
  temperature gradient.

Title: Nonresonant Resistive Dissipation of Incompressible
    Magnetohydrodynamic Waves
Authors: Califano, Francesco; Chiuderi, Claudio; Einaudi, Giorgio
Bibcode: 1990ApJ...365..757C
Altcode:
  The influence of departures from homogeneity on the dissipative
  properties of incompressible MHD waves are examined within the
  framework of an analytically solvable model in plane geometry. Only
  resistive dissipation is taken into account. The existence of a new
  class of rapidly oscillating solutions is proved for which the role
  of resistivity is not restricted to a single narrow layer, as in the
  well-known resonating case, but extends to the whole system.

Title: Energy Balance in Prominence-Corona Transition Regions
Authors: Chiuderi, C.; Chiuderi-Drago, F.
Bibcode: 1990IAUS..142..325C
Altcode:
  No abstract at ADS

Title: A Case for Alfven Wave Heating
Authors: Califano, F.; Chiuderi, C.; Einaudi, G.
Bibcode: 1990IAUS..142..223C
Altcode:
  The present study examines the resistive dissipation of Alfven waves in
  magnetically structured media within the framework of an analytically
  solvable model in plane geometry. It is shown that consideration of
  nonideal asymptotic boundary conditions gives rise to a new type of
  solutions for the resistively damped Alfven waves that are characterized
  by the appearance of very small scales in the x-direction. Since
  the normal modes can be thought of as the asymptotic state of the
  temporal evolution of an initial perturbation of arbitrary scale, the
  appearance of the small scales is interpreted as the result of the
  bilinear interaction of the initial perturbation and the nonuniform
  equilibrium structure. During the transient the spectrum of modes in the
  z-direction remains essentially unchanged, showing that the formation
  of small scales across the field takes place well before the possible
  development of the nonlinear mode-mode coupling along the field.

Title: MHD instabilities
Authors: Chiuderi, Claudio
Bibcode: 1990MmSAI..61..359C
Altcode:
  Recent theoretical studies of MHD instabilities in plasmas are reviewed,
  with an emphasis on those relevant to the solar corona. Consideration
  is given to the time evolution equations for a heated magnetized
  plasma losing energy via optically thin radiation, with dissipative
  effects described in terms of a finite constant isotropic resisitivity
  and shear viscosity and finite thermal conductivity channeled along
  the magnetic-field lines. Rayleigh-Taylor, Kruskal-Schwarzschild,
  and Kelvin-Helmholtz instabilities are characterized for various
  combinations of plasma parameters, and the refinements introduced
  to provide a greater degree of realism in solar-corona modeling are
  discussed. It is concluded that, although numerical simulations can
  now reproduce many features of solar plasmas, the study of analytical
  solutions must be pursued as a check on modeling accuracy.

Title: MHD of Solar Activity
Authors: Chiuderi, C.
Bibcode: 1990PDHO....7..146G
Altcode: 1990ESPM....6..146G; 1990dysu.conf..146G
  No abstract at ADS

Title: MHD of solar activity.
Authors: Chiuderi, C.
Bibcode: 1990PDHO....7..121C
Altcode: 1990dysu.conf..121C
  After a short overview of the subject, the general trends of the present
  efforts of modelisation of solar activity by means of MHD theory are
  discussed. Such trends are illustrated with the help of a few examples.

Title: Extragalactic Jets as Current-carrying Systems. I. Equilibrium
    and Stability
Authors: Chiuderi, Claudio; Pietrini, Paola; Ciamponi, Guidetta
   Torricelli
Bibcode: 1989ApJ...339...70C
Altcode:
  We present a model for extragalactic jets considered as magnetized
  current-carrying structures. Unlike previous models the return currents
  are assumed to flow within the jet itself. Standard MHD equations
  in cylindrical geometry are used to investigate the equilibrium and
  stability properties of such a model. Incompressible thermal matter
  flows are included in the equilibrium, but not in the stability
  analysis. Absolute stability regions are found and their boundaries
  are determined. Linear growth rates for the unstable m = 0 and m = 1
  modes are computed. The paper is intended as a basis for a subsequent
  one where the behavior of distribution of relativistic electrons in
  the given field is studied and predictions of observable polarization
  characteristics are made.

Title: MHD instabilities of a cylindrical plasma with a realistic
    energy equation
Authors: Torricelli-Ciamponi, Guidetta; Ciampolini, Vittorio;
   Chiuderi, Claudio
Bibcode: 1987JPlPh..37..175T
Altcode:
  The influence of a realistic energy equation on the stability of
  a cylindrical magnetized plasma in a force-free magnetic field is
  discussed. Thermal conduction, heating and line radiation are included
  in the treatment. Explicit growth rates for the m = 0 and m = 1 modes
  are derived and compared with the standard adiabatic or incompressible
  time-scales. Finally, the relevance of these results for laboratory
  and solar plasmas is discussed.

Title: Resistive Instabilities in Coronal Conditions
Authors: Batistoni, P.; Einaudi, G.; Chiuderi, C.
Bibcode: 1985SoPh...97..309B
Altcode:
  Resistive instabilities in a context referring to the solar corona
  are rigorously investigated. Various equilibrium configurations are
  considered, differing, among other things, by their behaviour with
  respect to fast, ideal instabilities. The computations presented cover
  in a unified scheme all known regimes of resistive modes and allow one
  to determine the fastest timescale over which resistivity can play a
  role. Comparisons with previous work as well as possible extensions
  are presented.

Title: Heating in the solar mantle.
Authors: Chiuderi, C.
Bibcode: 1985NASCP2358..101C
Altcode: 1985onhm.rept..101C
  In the case of the solar chromosphere and corona (the solar mantle)
  the primary energy source is the mechanical energy from photospheric
  motions. Plenty of energy is available; the problem is to transfer
  the needed amount of energy to the proper place to account for the
  observations. The global problem is reviewed from the point of view of
  the generation and transmission of energy, the intermediate storage
  of energy, and the release of energy in such a way that the observed
  features are generated.

Title: Resistive instabilities in astrophysical conditions - A
    critical discussion
Authors: Batistoni, P.; Einaudi, G.; Rubini, F.; Chiuderi, C.;
   Torricelli, G.
Bibcode: 1985IAUS..107..277B
Altcode:
  The linear development of resistive instabilities in astrophysical
  conditions is investigated numerically with allowance for the effects
  of gradients of the current density at the singular points that
  produce asymmetries in the F-profiles. An analysis is also made of
  the resistive behavior of a system with cylindrical symmetry under
  modes possessing an m = 1 azimuthal symmetry. The computational method
  used in the study is essentially a numerical boundary layer, with the
  internal solution computed exactly; a shooting technique is used to
  find the eigenvalues. This method is sufficiently fast and accurate for
  magnetic Reynolds numbers up to 10 to the 9th. The spatial structure
  and the maximum growth rate of the resistive modes are examined.

Title: Magnetic Fields and Thermal Structure of Solar Plasmas
Authors: Einaudi, G.; Torricelli-Ciamponi, G.; Chiuderi, C.
Bibcode: 1984SoPh...92...99E
Altcode:
  The connection between the magnetic field geometry and the thermal
  properties of solar coronal structures is investigated. Gravitational
  effects, that can modify the spatial dependence of the thermodynamical
  quantities, but have no influence on the plasma-field interaction,
  are omitted to simplify the problem. A series of two-dimensional models
  is constructed, in which a strong coupling between the magnetic field
  shear and the thermal structure of the loop is clearly pointed out.

Title: The role of magnetic fields in the heating of stellar
    atmospheres - Theory
Authors: Chiuderi, C.
Bibcode: 1983IAUS..102..375C
Altcode:
  The last ten years of observations have shown beyond doubt the
  fundamental role played by the magnetic field in the heating of stellar
  atmospheres. After the recognition of the extreme inhomogeneity of the
  solar corona, two new basic trends have appeared in the theoretical
  literature on the coronal-heating problem. One is the adoption of a
  global point of view that stresses the connection of the properties of
  the upper layers to those of the underlying ones. In this way a general
  framework is provided, capable of accommodating many possible heating
  mechanisms. The second trend is the explicit inclusion in the theory
  of the inhomogeneous nature of the stellar envelopes as a result of
  the presence of magnetic fields. The present status of knowledge on
  the subject, as determined by the above evolution of the theoretical
  approach, is reviewed.

Title: Equilibrium and Stability of Magnetized Plasmas
Authors: Chiuderi, C.
Bibcode: 1982MmSAI..53..863C
Altcode:
  No abstract at ADS

Title: Plasmi: il quarto stato della materia.
Authors: Chiuderi, C.
Bibcode: 1982GAst....8..361C
Altcode:
  No abstract at ADS

Title: Differential rotation, magnetic activity and X-ray emission
    of late type giants
Authors: Belvedere, G.; Chiuderi, C.; Paterno, L.
Bibcode: 1982A&A...105..133B
Altcode:
  The observations of X-ray emission from late type main sequence and
  giant stars show that a coronal heating due to acoustic waves is
  unlikely. <P />As suggested by Vaiana and Rosner, the conversion of
  magnetic into thermal energy may be responsible for the X-ray emission
  from such a kind of stars. <P />The proposed ingredients in our analysis
  are the differential rotation and dynamo action which are able to
  generate a magnetic activity at the star's surface which in turn gives
  rise to the observed X-ray emission. We assume that the interaction
  of rotation with convection, in stars possessing outer convective
  envelopes, is the dominant mechanism for generating differential
  rotation and dynamo action, and that the stressing of the coronal
  magnetic flux tubes by the surface turbulence, converting magnetic into
  thermal energy, determine the level of X-ray emission. <P />Therefore
  we compute a series of models of luminosity class III giant stars, and
  determine the surface X-ray flux. <P />Comparing these results with
  those concerning the late type main sequence star models, previously
  computed by the same authors, and with observations, it appears that
  the proposed mechanism is plausible.

Title: Diagnostic of coronal heating processes based on the emission
    measure of UV lines
Authors: Torricelli-Ciamponi, G.; Einaudi, G.; Chiuderi, C.
Bibcode: 1982A&A...105L...1T
Altcode:
  It is shown how data on the emission measure (EM) of solar UV lines can
  be used to gather information on the structure and heating processes
  of solar coronal loops, where the most important feature that must
  be incorporated is the presence of a minimum of the EM as a function
  of temperature. By doing this, and observing the requirement that the
  values of the observable parameters remain in the proper range, it is
  possible to strictly limit the value of the temperature exponent in the
  heating function. The loop models proposed present strong variations
  of the conductive fluxes, and exhibit a marked increase in the region
  where heating and radiation balance.

Title: The Formation of Solar Prominences
Authors: Chiuderi, C.
Bibcode: 1982ASSL...96..137C
Altcode: 1982spls.meet..137C
  A discussion of the physical conditions and numerical models describing
  the formation of solar prominences is presented. Prominences are noted
  to occur when thermal conduction is inhibited, with constraints by
  gravity and the strength of the magnetic field, which supports the
  filament against gravity. Linear growth has been calculated to take
  place where the perturbation energy is perpendicular to the field
  lines. The fastest linear stage has served as a starting point for
  nonlinear computations, which continue on to a new equilibrium. Location
  of the equilibrium has been accomplished with three different sets of
  boundary conditions, i.e., a fixed slab with no mass or heat flux from
  the boundaries, a fixed slab with no mass flux from the boundaries,
  and a fixed mass of plasma free to expand or contract, with boundaries
  at constant temperature and pressure. It is concluded that a homogeneous
  system linearly unstable to thermal instability evolves toward a stable
  inhomogeneous state where thin, cool condensations have formed.

Title: Loops, fields and all that
Authors: Chiuderi, C.
Bibcode: 1981SSRv...29..349C
Altcode:
  A greater understanding of solar coronal loops may explain the more
  elusive processes that heat the solar corona. Loops are strong emitters
  in the EUV, XUV, and X-ray ranges and have been recognized as the seat
  of coronal flares. They connect regions of opposite magnetic polarity
  and therefore delineate the gross topology of the coronal magnetic
  field. Since they result from the interplay of pressure, gravitational
  and magnetic forces, a quantitative model of the loops must be devised
  which will properly account for these forces. The mathematical problem
  to be solved is summarized, and the basic equations are presented. The
  solutions are simplified, however, since information is missing for some
  terms in the equations. It is concluded that high resolution instruments
  are needed to probe the solar atmosphere above the chromosphere for
  more information if these models are to be completed.

Title: Current Confinement in Solar Coronal Loops
Authors: Chiuderi, C.; Einaudi, G.
Bibcode: 1981SoPh...73...89C
Altcode:
  In this paper solar coronal loops are regarded as regions of localized
  current flows. The main purpose is to investigate the consequences
  of current confinement rather than to produce a model. The physical
  and observational basis for this assumption are presented as well
  as the connection with previous studies on loop structure. A proper
  choice of the current profile allows us to treat quantitatively the
  equilibrium structure of the loops and their MHD and resistive stability
  properties. Regions of absolute stability against ideal kink modes
  are found. Explicit growth rates for the tearing-mode instability are
  computed. The possible relevance of other resistive effects is also
  discussed and the crucial importance of the small-scale geometry of
  the magnetic field outlined.

Title: What can we learn from static models of coronal loops
Authors: Chiuderi, C.; Einaudi, G.; Torricelli-Ciamponi, G.
Bibcode: 1981A&A....97...27C
Altcode:
  The possible use of static coronal loop models to derive information on
  coronal heating mechanisms is considered. The conditions for the thermal
  stability of coronal loops with different sets of boundary conditions
  are investigated, and it is shown that stable configurations exist,
  including those with zero heat flux at the base. The use of generalized
  scaling laws permits the conclusion that no meaningful inferences on
  heating processes can be obtained from static models. A comparison
  with the results of other authors is also included.

Title: Stellar X-ray emission as a consequence of magnetic activity
Authors: Belvedere, G.; Chiuderi, C.; Paterno, L.
Bibcode: 1981A&A....96..369B
Altcode:
  It is noted that the discovery of stellar coronae for main sequence
  stars later than FO through K and M is one of the most important
  results of Einstein satellite observations. A theoretical estimate is
  given of the surface X-ray fluxes for these stars. It is noted that
  at coronal temperatures greater than 2,000,000 K X-ray luminosity is
  given by the radiative losses of systems of magnetic loops forming
  the active regions on the star's surface, namely by the summation of
  the single loop emission over the total number of loops in the active
  regions. Passing from luminosities to fluxes, it is shown that the
  surface X-ray flux is independent of the dimensions of the active
  regions present on the star's surface and depends only on the surface
  turbulence and the typical strength of the magnetic field in the active
  regions. The field twisted by turbulent motions is identified with
  the emerging mean toroidal field as computed by stellar dynamo models.

Title: Magnetic heating in the sun.
Authors: Chiuderi, C.
Bibcode: 1981ASIC...68..269C
Altcode: 1981spss.conf..269C
  The observational evidence for magnetic heating in the solar corona
  is presented. The possible ways of investigating theoretically the
  nature of the heating processes are critically discussed. Merits
  and disadvantages of the basic mechanisms so far proposed are
  reviewed. Finally, a preliminary application of the magnetic heating
  concept to stellar coronae is presented.

Title: High energy phenomena in the sun
Authors: Chiuderi, C.
Bibcode: 1981IAUS...94..367C
Altcode:
  Solar flares are considered as a model of a widespread astrophysical
  phenomenon: the violent conversion of some form of energy into heat
  and the kinetic energy of accelerated particles. Following a brief
  description of the observational characteristics of solar flares in
  the chromosphere and corona, attention is given to mechanisms for
  the accumulation of magnetic energy in the solar atmosphere and its
  subsequent release by processes of resistive dissipation and dynamical
  reconnection giving rise to a flare. It is noted that measurements
  of the coronal magnetic field made by EUV polarimeters of the type
  planned for the Solar Maximum Mission and Spacelab are necessary for
  the definitive solution of the problem of energy release in flares.

Title: The stability properties of cylindrical force-free fields:
    effect of an external potential field
Authors: Chiuderi, C.; Einaudi, G.; Ma, S. S.; van Hoven, G.
Bibcode: 1980JPlPh..24...39C
Altcode:
  A large-scale potential field with an embedded smaller-scale force-free
  structure ( × B = αB) is studied in cylindrical geometry. We consider
  cases in which α goes continuously from a constant value α<SUB>0</SUB>
  on the axis to zero at large r. Such a choice of α(r) produces fields
  which are realistic (few field reversals) but not completely stable. The
  MHD-unstable wavenumber regime is found. Since the considered
  equilibrium field exhibits a certain amount of magnetic shear,
  resistive instabilities can arise. The growth rates of the tearing
  mode in the limited MHD-stable region of º space are calculated,
  showing time-scales much shorter than the resistive decay time.

Title: The solar corona.
Authors: Chiuderi, C.
Bibcode: 1980HiA.....5..335C
Altcode:
  Recent observations from space have shown that the solar corona is
  spatially a very structured medium and temporally a very dynamic
  one. The consequent changes in the current theoretical ideas about
  coronal physics are reviewed. Particular emphasis is placed on the
  role of magnetic fields in shaping and heating the coronal structures.

Title: The filament instability in a sheared field
Authors: Chiuderi, C.; van Hoven, G.
Bibcode: 1980IAUS...91..295C
Altcode:
  A self-consistent calculation of the thermal instability in a
  non-uniform field is performed. It is shown how the dynamic response
  of density and temperature to the competing effects of optically-thin
  radiation and field-collimated thermal conduction leads to the formation
  of characteristic knife-blade filaments. The dynamic calculation
  reflects the sheared magnetic field and the finite geometry, as well
  as the intimate relation of the sheared magnetic fields to flares.

Title: Recent development in coronal structure thermodynamics and
    stability.
Authors: Chiuderi, C.
Bibcode: 1980AnPh....5..425C
Altcode: 1980mhda.conf..425C
  No abstract at ADS

Title: Wave propagation in a non-isothermal atmosphere and the solar
    five-minute oscillations
Authors: Chiuderi, C.; Giovanardi, C.
Bibcode: 1979SoPh...64...27C
Altcode:
  This paper presents a detailed discussion of the properties of
  linear, periodic acoustic waves that propagate vertically in a
  non-isothermal atmosphere. In order to retain the basic feature of
  the solar atmosphere we have chosen a temperature profile presenting
  a minimum. An analytical solution of the problem is possible if
  T/μ, μ being the mean molecular weight, varies parabolically with
  height. The purpose of this study is to point out the qualitative
  differences existing between the case treated here and the customary
  analysis based on a locally isothermal treatment. The computed velocity
  amplitude and the temperature-perturbation as functions of the wave
  period exhibit a sharp peak in the region between 180 and 300 s, thus
  showing the possibility of interpreting the five-minute oscillations
  as a resonant phenomenon. The propagating or stationary nature of
  the waves is investigated by a study of the phase of the proposed
  analytical solution.

Title: The dynamics of filament formation: the thermal instability
    in a sheared magnetic field.
Authors: Chiuderi, C.; van Hoven, G.
Bibcode: 1979ApJ...232L..69C
Altcode:
  The dynamics of the thermal plasma instability in a nonuniform magnetic
  field, involved in the formation of solar filaments or prominences
  in sheared coronal magnetic fields, are examined. An expression is
  derived for a perturbation of equilibrium conditions corresponding
  to the physical configuration to observed filaments, which allows
  the dynamic response of plasma pressure, density and temperature to
  optically thin radiation and field-collimated thermal conduction to
  be determined. Numerical solutions to the equations demonstrate the
  formation of characteristic knife blade condensations and can predict
  the initial temporal and spatial scales of coronal filament appearance.

Title: High-Energy Phenomena on the Solar Surface
Authors: Chiuderi, C.
Bibcode: 1979ASSL...75...33C
Altcode: 1979sss..meet...33C
  This paper reviews observations of events in the solar atmosphere
  that involve the presence of suprathermal particles and the emission
  of radiation whose brightness temperature exceeds the kinetic
  temperature. Observed characteristics of solar flares are discussed,
  emphasizing the buildup of energy prior to a flare and the mechanism
  of primary energy release. Magnetic-field reconnection is taken to be
  the best candidate for the mechanism of energy conversion required to
  fuel a flare. Several phenomenological flare models are considered,
  along with shortcomings of these models.

Title: Does the structure of the chromosphere-corona arise entirely
    from small-scale MHD effects?
Authors: Chiuderi, C.
Bibcode: 1979ssms.conf..105C
Altcode:
  No abstract at ADS

Title: Polytropic models of radio stars.
Authors: Chiuderi, C.; Torricelli Ciamponi, G.
Bibcode: 1978A&A....69..333C
Altcode:
  Summary. This paper extends our previous work on models for radio
  emitting stars undergoing mass loss. The emission is assumed to
  be of thermal nature and the dynamics of the envelope is treated
  in the polytropic approximation. No limitations on the value of the
  polytropic index are introduced. Analytic results are derived whenever
  possible. For the other cases, the results of numerical integration of
  the model are fitted in a simple mathematical form that allows an easy
  application of the model to the observations. Detailed predictions,
  in particular for the mass-loss rate, are made for a few selected
  stars. A very good agreement is found with the estimates of the same
  quantities found by different authors. The possibility of reproducing
  the infrared spectrum is also discussed. Key words: radiostars stellar
  winds - mass loss

Title: The structure of coronal magnetic loops. II: MHD stability
    theory.
Authors: Giachetti, R.; van Hoven, G.; Chiuderi, C.
Bibcode: 1977SoPh...55..371G
Altcode:
  We present the second part of a complete theory for the plasma and field
  structure of a cool coronal arch, corresponding to those observed in
  the EUV from Skylab. The global magneto-hydrodynamic (MHD) stability
  of a previously described equilibrium-loop model is evaluated, and
  compared with that of an unmodified ambient force-free field. The
  influence of the photospheric boundary condition is also evaluated,
  producing a specification of stability limits which depend on the
  relative field and plasma pressures and scale widths. The resulting
  restrictions on the allowable field configuration of a coronal loop are
  then compared with observed values. The implications of this general
  method for deducing small-scale coronal magnetic-field structure from
  the measured plasma profile of an emissive feature are also described.

Title: The structure of coronal magnetic loops. I: Equilibrium theory.
Authors: Chiuderi, C.; Giachetti, R.; van Hoven, G.
Bibcode: 1977SoPh...54..107C
Altcode:
  We present here a model, based on observations, for the magnetic-field
  equilibrium of a cool coronal loop. The pressure structure, taken
  from the Harvard/Skylab EUV data, is used to modify the usual
  force-free-field form in quasi-cylindrical symmetry. The resulting
  field, which has the same direction but different strength, is
  calculated and its variation displayed. Finally, localized interchange
  stability is evaluated and discussed, as the first step in a subsequent
  complete magnetohydrodynamic-stability analysis.

Title: The solar corona and the origin of the solar wind
Authors: Chiuderi, C.
Bibcode: 1977MmSAI..48..561C
Altcode:
  The paper deals with the properties of the solar corona and the
  techniques by which they have been observed. The corona is treated,
  in general, as a spherically symmetric stationary gas. This model,
  although admittedly unrealistic, has a certain right to exist if it is
  considered as an average model (corresponding to a lower resolution
  or to a greater distance to the sun). Particular attention is given
  to the problem of coronal heating and to the solar wind.

Title: Radio emission from mass-outflow stars.
Authors: Chiuderi, C.; Torricelli Ciamponi, G.
Bibcode: 1977A&A....59..395C
Altcode:
  The problem of the radio emission from the extended envelopes
  surrounding early-type stars undergoing mass loss is considered. The
  emission is interpreted as due to thermal bremsstrahlung processes. The
  dynamics of the expanding atmosphere is treated in the polytropic
  approximation without prescribing the density and temperature profiles,
  as done in previous models. For a particular value of the polytropic
  index falling in the physically interesting range, analytical
  expressions are deduced for the spectral index, the radio flux, and
  the angular size of the emitting object, as well as a relationship
  between these quantities and the mass-loss rate. The model applied to
  P Cyg and MWC 349 gives good agreement with the existing data.

Title: Cyclotron instabilities of a magnetized electron plasma with
    anisotropic temperatures
Authors: Chiuderi, C.; Einaudi, G.; Giachetti, R.
Bibcode: 1977JPlPh..17..453C
Altcode:
  The dispersion relation for an electron plasma in a magnetic field
  is investigated for a bi-Maxwellian distribution function. A new set
  of solutions for non-perpendicular propagation is found. The linear
  growth rates are computed and the instability regions in the (k, cos
  θ) plane are determined. An approximate analytical treatment of the
  problem is also given for certain ranges of the parameters.

Title: Flare mechanisms
Authors: Chiuderi, C.
Bibcode: 1977MmSAI..48..321C
Altcode:
  The paper considers a 'standard' model of a solar flare as defined
  by morphology, energetics (thermal, gravitational and magnetic), and
  temporal evolution; the quantitative data considered are characteristic
  of a large flare (3 plus magnitude). Detailed consideration is given to
  the three stages of flare evolution: preparatory, peak, and decay. Flare
  evolution is discussed in reference to three determining factors:
  (1) the macroscopic instability which leads to intensification of
  local currents, (2) plasma turbulence, and (3) particle acceleration
  mechanisms.

Title: A model for a stable coronal loop.
Authors: van Hoven, G.; Chiuderi, C.; Giachetti, R.
Bibcode: 1977ApJ...213..869V
Altcode:
  A plasma-physics model of a stable active-region arch is presented which
  corresponds to the structure observed in the EUV. Pressure gradients
  are seen, so that the equilibrium magnetic field must depart from
  the force-free form valid in the surrounding corona. The data and the
  approximate cylindrical symmetry are exploited to develop a modified
  form of the commonly assumed sheared-spiral structure. The dynamic MHD
  behavior of this pressure/field model is then evaluated by the Newcomb
  criterion (1960) from controlled-fusion physics, and the results
  show short-wavelength stability in a specific parameter range. For
  pressure profiles with widths of the order of the magnetic-field
  scale, the possibility is demonstrated that such arches can persist
  for reasonable periods. Finally, the spatial proportions and magnetic
  fields of a characteristic stable coronal loop are described.

Title: Mechanisms of Heating and Heat Transfer in the Outer Solar
    Atmosphere
Authors: Chiuderi, C.; Kuperus, M.
Bibcode: 1977ebhs.coll..223C
Altcode: 1977IAUCo..36..223C
  No abstract at ADS

Title: Circular polarization and magnetic fields of white dwarfs.
Authors: Chiuderi, C.; Silvi, M.
Bibcode: 1976MmSAI..47...65C
Altcode:
  A simple method to estimate the strength of the surface magnetic
  field of a white dwarf from the degree of circular polarization in
  its continuum spectrum is proposed. The method is applied to the
  observed spectra of G99-37 and G227-35 giving a fairly good fit in
  the optical range.

Title: Solar five-minute oscillations as a resonance phenomenon.
Authors: Chiuderi, C.; Giovanardi, C.
Bibcode: 1975ApJ...200L.165C
Altcode:
  The response of a nonisothermal gravitational atmosphere to an
  oscillatory perturbation is studied in the case of a parabolic
  temperature profile. The exact analytical solution is then applied to a
  model solar atmosphere. An interpretation of the 5-minute oscillations
  as free oscillations of the atmosphere as a whole is proposed.

Title: The LOFER (Landau Orbital Ferromagnetism) Mechanism for the
    Generation of Intense Magnetic Fields
Authors: Chiuderi, C.; Lee, H. J.
Bibcode: 1975NYASA.257...82C
Altcode:
  No abstract at ADS

Title: Acoustic Waves in the Lower Solar Atmosphere
Authors: Chiuderi, C.; Giovanardi, C.
Bibcode: 1975SoPh...41...35C
Altcode:
  The propagation and dissipation of acoustic waves in the lower solar
  atmosphere is studied. The level of shock formation is computed for
  various initial conditions. It is shown that shocks form rather low
  in the atmosphere and that this result does not depend critically on
  the assumed initial conditions.

Title: Proceedings of the First European Solar Meeting. Florence,
    February 25 - 27, 1975.
Authors: Chiuderi, C.; Landini, M.; Righini, A.; Zwaan, C.
Bibcode: 1975MmArc.105....1C
Altcode:
  No abstract at ADS

Title: CESRA-5
Authors: Chiuderi, C.; Landini, M.; Righini, A.
Bibcode: 1975cesra...5.....C
Altcode:
  No abstract at ADS

Title: European solar meeting : 1 : 1975
Authors: Chiuderi, C.
Bibcode: 1975esm..meet.....C
Altcode:
  The papers in this collection report on current European research in
  solar physics, recently developed instruments for solar observations,
  and future developments in this field. Specific topics include a
  theoretical review of dynamic processes in the solar atmosphere,
  magnetic structures in the chromosphere and photosphere, magnetic
  structures observed in the corona, and the solar brightness temperature
  in the far infrared. Attention is given to future solar-physics programs
  in space, current research being conducted in a number of Western
  and Eastern European countries, the design of a high-sensitivity
  radioheliograph, a proposal for a collecting array of 144 antennas,
  and a film of the solar spectrum during an eclipse. Individual items
  are announced in this issue.

Title: Neutrino Reactions in Strong Magnetic Field
Authors: Canuto, V.; Chiuderi, C.; Chou, C. K.; Fassio-Canuto, L.
Bibcode: 1974Ap&SS..28..145C
Altcode:
  We present the energy losses due to several neutrinos processes: (1)
  synchrotron neutrinos, (2) pair annihilation neutrinos, (3) plasmon
  neutrinos, and (4) photoneutrinos in the presence of a superstrong
  magnetic field. Numerical results are tabulated and illustrated for
  several values of densities and temperatures. In the low density regime
  (ϱ≲10<SUP>7</SUP> g cm<SUP>-3</SUP>) the presence of a magnetic
  field decreases the luminosity, whereas the opposite is true at higher
  densities. This last effect is however almost entirely due to the
  existence of a new process the synchrotron neutrinos that disappear
  whenH→0. Even though the overall effect can only be quantitatively
  ascertain after a complete cooling computation is performed, one should
  however expect a much lower temperature for neutron star surface than
  the one computed in theH=0 case.

Title: Spectral and Polarization Properties of Radiation Generated
    by Plasma Turbu- lence
Authors: Chiuderi, C.; Veltri, P.
Bibcode: 1974A&A....30..265C
Altcode:
  Summary. We have studied a system which consists of a cold plasma
  containing an ultrarelativistic distribution of electrons. The response
  of such a system to a periodic electromagnetic disturbance is first
  discussed. The problem is then specialized to the case of a longitudinal
  stationary plasma wave. The emission and propagation of radiation in
  such a system is analysed in detail by a method which is analogous to
  the one used in synchro tron radiation theory. Explicit results are
  given for a power-law distribution of relativistic electrons, and they
  are compared to synchrotron emission under the same conditions. It
  is shown that the frequency dependence and polarization are quite
  similar in the two cases. Key words: plasma radiation mechanism -
  transfer equation - polarized radiation

Title: High Resolution Studies of Type III Solar Radio Bursts
    (presented by H. Rosenberg)
Authors: Chiuderi, C.; Giachetti, R.; Mercier, C.; Rosenberg, H.;
   Slottje, C.
Bibcode: 1974IAUS...57..225C
Altcode:
  No abstract at ADS

Title: Fine Structure in Type IV Solar Radio Bursts (presented by
    H. Rosenberg)
Authors: Caroubalos, C.; Pick, M.; Chiuderi, C.; Giachetti, R.;
   Rosenberg, H.; Slottje, C.
Bibcode: 1974IAUS...57..291C
Altcode:
  No abstract at ADS

Title: A Dynamical Model for the Chromosphere-Corona Transition Region
Authors: Chiuderi, Claudio; Riani, Iacopo
Bibcode: 1974SoPh...34..113C
Altcode:
  A dynamical, homogeneous model of the chromosphere-corona
  transition region and of the lower corona is presented, based on the
  hydrodynamical equations and on a semi-empirical relation deduced
  from radio observations. The model is shown to be in agreement with
  radio and UV observations and with the particle flux given by solar
  wind measurements. A comparison with the analogous static model shows
  that dynamical effects are very small.

Title: Excitation of Longitudinal Waves in a Magnetized Plasma under
    Coronal Conditions
Authors: Chiuderi, C.; Giachetti, R.; Rosenberg, H.
Bibcode: 1974cesra...4..155C
Altcode:
  No abstract at ADS

Title: NonLinear Wave Coupling in Type IV Solar Radio Bursts
Authors: Chiuderi, Claudio; Giachetti, Riccardo; Rosenberg, Hans
Bibcode: 1973SoPh...33..225C
Altcode:
  In order to explain a fine structure of parallel ridges in stationary
  type IV continua, the emission due to the coupling of electrostatic
  upper hybrid waves and Bernstein waves at the sum frequency of the upper
  hybrid and harmonics of the gyro frequency has been calculated. If
  the energy density of these electrostatic waves is of the order of
  10<SUP>-3</SUP> times the thermal energy density, then the observed
  zebra pattern can be emitted by a region with a diameter of ∼
  10<SUP>3</SUP> km.

Title: Nonlinear wave coupling in type IV solar radio bursts.
Authors: Chiuderi, C.; Giachetti, R.; Rosenberg, H.
Bibcode: 1973UtrOv.237.....C
Altcode:
  No abstract at ADS

Title: Coronal Abundance of Elements and a Model of the Quiet Sun
    from Radio Observations
Authors: Chiuderi, Claudio; Chiuderi Drago, Franca; Noci, Giancarlo
Bibcode: 1972SoPh...26..343C
Altcode:
  It is shown that the combined use of radio observations of the quiet Sun
  and UV line intensities allows to compute the absolute coronal abundance
  of the elements. The abundances found by this method agree very well
  with the most recent determinations. A model of the transition region
  and corona in hydrostatic equilibrium is also presented. Similarities
  and differences with models based on UV observations are discussed.

Title: Coronal Abundances and a Model of the Quiet Sun from Radio
    Observations
Authors: Chiuderi, C.; Chiuderi Drago, F.; Noci, G.
Bibcode: 1972BAAS....4T.379C
Altcode:
  No abstract at ADS

Title: Evidence for non linear effects in solar metric radiation
Authors: Chiuderi, C.
Bibcode: 1972ppsr.conf..288C
Altcode:
  No abstract at ADS

Title: Radio Model of the Transition Layer in Solar Active Regions
Authors: Chiuderi, Claudio; Drago, Franca Chiuderi; Noci, Giancarlo
Bibcode: 1971SoPh...17..369C
Altcode:
  A model of the transition layer of an active region of the Sun
  is presented based on radio observations. The model is deduced by
  using the Laplace transform of the brightness temperature and the
  hydrostatic equilibrium equation. A rational function, well-behaved in
  the coronal region, has been used to represent the observed brightness
  temperature. The model indicates the existence of a very steep
  temperature gradient and suggests the presence of a constant conductive
  flux from the corona into the chromosphere. Both these conclusions are
  quantitatively in a very good agreement with those deduced from the
  UV emission lines observations, thus removing a previous discrepancy
  between radio and optical based models. It is also shown that the
  presence of a weak magnetic field does not alter the above conclusions.

Title: Model of the quiet sun and coronal abundance of elements from
    radio observations
Authors: Chiuderi, C.; Chiuderi-Drago, F.; Noci, G.
Bibcode: 1971cesra...2...55C
Altcode:
  No abstract at ADS

Title: Plasmon Neutrinos Emission in a Strong Magnetic Field. II:
    Longitudinal Plasmons
Authors: Canuto, V.; Chiuderi, C.; Chou, C. K.
Bibcode: 1970Ap&SS...9..453C
Altcode:
  The decay of a longitudinal plasmon into two neutrinos is studied
  in the presence of a strong magnetic field. Contrary to the
  transverse case, for longitudinal plasmons the existence of a new
  mode, entirely dependent on the magnetic field, greatly enhances
  the energy loss at high densities. Denoting byQ <SUB>H</SUB>andQ
  <SUB>0</SUB>the neutrino energy losses with and without magnetic field
  respectively, the situation is as follows: atH≃10<SUP>11</SUP>
  G andT≥10<SUP>9</SUP>K,Q <SUB>0</SUB>≫10<SUP>5</SUP> Q
  <SUB>H</SUB>for ϱ&lt;10<SUP>11</SUP>g cm<SUP>-3</SUP>, WhileQ
  <SUB>H</SUB>≫10<SUP>10</SUP> Q <SUB>0</SUB>for ϱ&gt;10<SUP>11</SUP>g
  cm<SUP>-3</SUP>. A second physically interesting feature is the
  anisotropic character of the energy loss which is highly peaked along
  the field lines, giving rise to a shorter cooling time in that direction
  than in any other.

Title: Plasmon Neutrinos Emission in a Strong Magnetic Field. I:
    Transverse Plasmons
Authors: Canuto, V.; Chiuderi, C.; Chou, C. K.
Bibcode: 1970Ap&SS...7..407C
Altcode:
  In this paper we generalize the Adams, Ruderman, Woo and Zaidi plasmon
  decay process to include the presence of a strong magnetic field. Two
  cases are studied; propagation parallel and perpendicular to the
  magnetic field. In either case we found that relevant changes only
  show forH≌10<SUP>12</SUP> 10<SUP>13</SUP>G.

Title: Shape of the Crab Pulsar and its Period Fluctuations
Authors: Chiuderi, Claudio; Occhionero, Franco
Bibcode: 1970Natur.226..337C
Altcode:
  RICHARDS et al.<SUP>1</SUP> have recently recorded sinusoidal
  variations in the arrival times of radio pulses from NP 0532 with
  a period of about three months and an amplitude Δ<SUB>τ</SUB>=
  6 × 10<SUP>-4</SUP> s. This effect can be interpreted in terms
  of genuine sinusoidal variations of the circular frequency of the
  Crab pulsar where Ω ~= 200 s<SUP>-1</SUP>, ω ~= 10<SUP>-6</SUP>
  s<SUP>-1</SUP>, A ~= 10<SUP>-10</SUP>. Equation (1) can be explained
  by the widely accepted oblique rotator model<SUP>2-4</SUP> simply by
  investigating an interesting consequence of the possible ellipticity of
  the neutron star. To account for the history and energy balance of the
  Crab Nebula<SUP>3</SUP>, an upper limit must be placed<SUP>4,5</SUP>
  to this ellipticity, such that the gravitational quadrupole radiation
  dominates the magnetic dipole radiation only in the early life of the
  pulsar. It turns out that the explanation given here for the anomalies
  in the pulse arrival times provides in the end an even stronger limit
  to the deviations from spherical symmetry allowed in a neutron star.

Title: Transverse Electrical Conductivity of a Relativistic Gas in
    an Intense Magnetic Field
Authors: Canuto, V.; Chiuderi, C.
Bibcode: 1970PhRvD...1.2219C
Altcode:
  The transverse electrical conductivity is computed for a system
  of degenerate relativistic electrons in a strong magnetic field
  H~10<SUP>10</SUP>-10<SUP>13</SUP> G. As suggested by pulsar models,
  such fields exist in nature in collapsed bodies, like neutron
  stars. The present computation is valid in the outer regions of the
  star where the scatterers are not degenerate, while the electrons
  are taken to be at zero temperature. The scattering mechanism
  is assumed to be the electron-ion Coulomb scattering. Numerical
  values of the transverse conductivity are given in the range
  10<SUP>9</SUP>&lt;=H&lt;=10<SUP>13</SUP> G, and a comparison is made
  with the longitudinal and zero-field conductivities. It is found that
  for densities 10<SUP>7</SUP>&lt;=ρ&lt;=5×10<SUP>7</SUP>,
  σ<SUB>II</SUB>~20σ<SUB>0</SUB> and
  σ<SUB>0</SUB>~3σ<SUB>⊥</SUB>. As the density increases, both
  σ<SUB>⊥</SUB> and σ<SUB>II</SUB> tend to σ<SUB>0</SUB>.

Title: Physical Sciences: New Source of Intense Magnetic Fields in
    Neutron Stars
Authors: Canuto, V.; Chiu, H. Y.; Chiuderi, C.
Bibcode: 1970Natur.225...47C
Altcode:
  RECENTLY there has been interest in the problem of intense magnetic
  fields (IMF) in gravitationally collapsed bodies<SUP>1-6</SUP>. In
  particular, the radio emission from neutron stars (pulsars) suggests
  strong magnetic fields of the order of 10<SUP>12</SUP> G (refs. 5
  and 7). According to the law of flux conservation, in a collapse
  process the magnetic fields strength increases as the square of the
  contracting factor a (&gt; 1). If the initial magnetic field is of the
  order of 10<SUP>3</SUP> G (the field in sunspots) before collapse, then
  assuming contraction from a star of one solar radius ~10<SUP>11</SUP>
  cm to that of a neutron star of 10<SUP>6</SUP> cm, a field strength
  of 10<SUP>13</SUP> G may be achieved. Magnetic fields in ordinary
  stars are usually attributed to non-equilibrium processes such as the
  existence of currents in the form of drifting charges, but we have
  recently shown that a new kind of quasi -equilibrium state exists,
  which possesses a uniform self-consistent magnetization<SUP>8</SUP>.

Title: New State of Ferromagnetism in Degenerate Electron Gas and
    Magnetic Fields in Collapsed Bodies
Authors: Lee, Hyung Joon; Canuto, Vittorio; Chiu, Hong-Yee; Chiuderi,
   Claudio
Bibcode: 1969PhRvL..23..390L
Altcode:
  A new state of "ferro" magnetism in a degenerate electron gas is found
  and shown to be stable. This magnetism is the sum of all microscopic
  magnetic moments associated with electrons in their respective Landau
  levels while the Landau levels of the system are in turn maintained
  by this macroscopic magnetization. The maximum field in the Landau
  orbital ferromagnetism state is 10<SUP>7</SUP> G for white-dwarf
  densities and 10<SUP>12</SUP> G for neutron-star densities.

Title: Solution of the Dirac equation in orthogonal electric and
    magnetic fields.
Authors: Canuto, V.; Chiuderi, C.
Bibcode: 1969NCimL...2..223C
Altcode:
  No abstract at ADS

