Problems and progress in flare fast particle diagnostics

Recent progress in the diagnosis of flare fast particles is critically discussed with the main emphasis on high resolution hard X-ray (HXR) data from RHESSI and coordinated data from other instruments. Spectacular new photon data findings are highlighted as are advances in theoretical aspects of their use as fast particle diagnostics, and some important comparisons made with interplanetary particle data. More specifically the following topics are addressed:

• (a)RHESSI data on HXR (electron) versus gamma-ray line (ion) source locations.
• (b)RHESSI hard X-ray source spatial structure in relation to theoretical models and loop density structure.
• (c)Energy budget of flare electrons and the Neupert effect.
• (d)Spectral deconvolution methods including blind target testing and results for RHESSI HXR spectra, including the reality and implications of dips inferred in electron spectra.
• (e)The relation between flare in situ and interplanetary particle data.

     

Experimental study of morphological and convective instabilities: The MEPHISTO space program

It is now well established that the morphological instability, i.e. the transition during solidification from a planar L/S interface to a cellular one, is strongly influenced by convection. The most recent theories on this topic, which are very advanced, suffer from the lack of experimental tests because uncontrolled convective effects cannot be avoid on the ground. Moreover the check of all the pertinent solidification parameters are not controlled in the same time or measured in real time. After a review of the main 1g experiments and their own limitations, we describe a new apparatus (MEPHISTO) which allows :

• •in-situ measurements of the main solidification parameters and in particular the undercooling at the solidification front in real time by a non perturbative method.
• •real time supervision of convective motions influence on crystal growth. First results obtained under 1g condition are presented :
  • ◦hydrodynamic scaling laws testing,
  • ◦instabilities detection,
  • ◦transient phenomena.

Main space results are then anticipated including the role of g-jitters.     

Space technologies for short-term earthquake warning

Recent theoretical and experimental studies explicitly demonstrated the ability of space technologies to identify and monitor the specific variations at near-earth space plasma, atmosphere and ground surface associated with approaching severe earthquakes (named as earthquake precursors) which appear several days (from 1 to 5) before the seismic shock over the seismically active areas. Several countries and private companies are in the stage of preparation (or already launched) the dedicated spacecrafts for monitoring of the earthquake precursors from space and for short-term earthquake prediction. The present paper intends to outline the optimal algorithm for creation of the space-borne system for the earthquake precursors monitoring and for short-term earthquake prediction. It takes into account the following:

• 1.Selection of the precursors in the terms of priority, considering their statistical and physical parameters.
• 2.Configuration of the spacecraft payload.
• 3.Configuration of the satellite constellation (orbit selection, satellite distribution, operation schedule).
• 4.Different options of the satellite systems (cheap microsatellite or comprehensive multisatellite constellation).

Taking into account that the most promising are the ionospheric precursors of earthquakes, the special attention is devoted to the radiophysical techniques of the ionosphere monitoring. The advantages and disadvantages of such technologies as vertical sounding, in-situ probes, ionosphere tomography, GPS TEC and GPS MET technologies are considered.     

Period activity relation for the W UMa-type systems

A large sample of times of minima of W UMa-type systems was analysed to study possible changes of their orbital periods. The main results are as follows :

• 1.every system changes period (the mean interval of period stability is about 11 years).
• 2.more active contact systems change periods in both signs (shortening and lengthening) with the same frequencies and similar values (about 10⁻⁶ day).

The characteristic time-scales and high symmetry of period changes of W UMa's do not confirm the prediction of the thermal-relaxation theory. The most promising explanation of these changes seems to be magnetic cycling activity as a cause of period changes for all the W UMa-type systems.     

Short wavelength ion-cyclotron waves upstream of the earth's bow shock

Ion beams reflected from the bow shock are shown to excite ioncyclotron instability in the solar wind. For the parameters relevant to the solarwind upstream of the terrestrial bow shock the growth

is found to be a significant fraction of the ion cyclotron frequency μ_i for K

_M ≳ 2. Here K is the wave vector and

_M is the proton gyro radius. The corresponding wave frequency ω_r is found to be from ∼ 0.5 to several times the ion gyrofrequency μ_i. Since the group velocities of these waves are small they can efficiently interact with the plasma in and near the generating region.     

A 3NM-64_He added to LARC for Solar Extreme Event studies during solar cycle 24

The Antarctic Laboratory for Cosmic Rays (LARC, acronym for Laboratorio Antartico per i Raggi Cosmici or Laboratorio Antártico para Rayos Cósmicos) operates on King George Island (South Shetlands). Since January 1991 a standard 6NM-64 detector has been recording continuous cosmic ray measurements and several Ground-Level Enhancements have been registered. Here we describe the different phases performed in Italy for the realization of a 3NM-64_³He detector, which started its measurements during the Italian XXII Antarctic Summer Campaign. Data recorded during solar activity cycle 24 will furnish an useful research tool for the next Solar Extreme Events.     

Meteorite magnetization and paleointensity

The five chemical classes of chondrite, i.e. E-, H-, L-, LL- and C-chondrite, and three major classes of achondrite, i.e. diogenite, eucrite plus howardite, and ureilite, are magnetically identified to respective separated domains on an I_s (α)/I_s versus I_s diagram, where I_s and I_s (α) denote respectively the saturation magnetization and the saturation magnetization of α-phase alone. Three major groups of iron meteorite, i.e. hexahedrite plus Ni-poor ataxite, octahedrite and Ni-rich ataxite, are magnetically identified to respective domains on an I_s (α)/I_s versus

→ α diagram, where

→ α denotes

→ α transition temperature of kamacite phase in the cooling process. The magnetic classification schemes well represent the chemical characteristics of each meteorite class. The paleointensity (F_p) of meteorites determined to date can be summarized as F_p=0.01 ～ 0.1 Oe for eucrites and ureilites, F_p^? 1 Oe for C-chondrites, and F_p^? 10 Oe for E-chondrites.