The prospects of using extreme relativistic laser-matter interactions for laboratoryastrophysics are discussed. Laser-driven process simulation of matterdynamics at ultra-high energy density is proposed for the studies of astrophysical compactobjects and the early universe.

Magnetic field generation in the Universe is still an open problem. Possible mechanismsinvolve the Weibel instability, due to anisotropic phase-space distributions, as well asthe Biermann battery, due to misaligned density and temperature gradients. Thesemechanisms can be reproduced in scaled laboratory experiments. In this contribution weestimate the relative importance of these two processes and explore the laser-energyrequirements for producing Weibel dominated shocks.

Cosmic rays are accelerated in astrophysical plasmas which collide at supersonic speedswhere shock waves are formed, and along with other instabilities, they compete for thedissipation and acceleration mechanisms. The diffusive acceleration mechanism plays aleading role in the explanation of very high energy cosmic rays observed. In thismechanism, particles are repeatedly gaining energy in multiple crossings of anastrophysical shock discontinuity, due to collisions with upstream and downstream magneticscattering centers, resulting in a power-law spectrum extending up to very high energies.Relativistic jets and their shocks in Active Galactic Nuclei (AGN) is a prominent sourcefor particle acceleration. Especially, relativistic single or multiple shocks have beentheorized and observed along the jets of AGN and are claimed to be responsible foraccelerating even the highest-energy cosmic rays observed. In this paper we will reportand discuss the cosmic ray acceleration efficiency and properties of single or multipleshocks in the limit of relativistic plasmas in AGN jet environments.

A two-dimensional numerical study of the expansion of a dense plasma through a morerarefied one is reported. The electrostatic ion-acoustic shock, which is generated duringthe expansion, accelerates the electrons of the rarefied plasma inducing a superthermalpopulation which reduces electron thermal anisotropy. The Weibel instability is thereforenot triggered and no self-generated magnetic fields are observed, in contrast withpublished theoretical results dealing with plasma expansion into vacuum.

Using powerful lasers, we are now able to produce in laboratory relevant regimes ofdensity, temperature and velocity to create a diagnosable exact scaled model of magneticcataclysmic variables accretion column. We present here preliminary results of a numericalmodeling of these astrophysical objects which will allow us to precise the experimentalsetup of future experiments.

CNES, ESA and NASA have invested in helioseismic and asteroseismic disciplines for 2decades with SoHO (1995–2015), COROT (2006–2013), KEPLER (2009–2014), PICARD (2010–2013)and SDO (2010–2015). These missions focus on the stellar internal dynamics and theirinfluence of neighboring planets. Progress along this path requires that the microscopicphysics is well under control, but several seismic probes indicate some discrepancieswhich justify new investigations of the energy transport in radiative zones of the Sun andmassive stars, despite strong efforts dedicated to reaction rates, screening, equation ofstate and opacity coefficients between 1990 and 2000. We describe here how the OPACconsortium tackles the complex problem of photon absorption by matter both theoreticallyand experimentally, by using high energy laser facilities. These studies might be alsouseful for other disciplines like fusion for energy and X-ray spectroscopy astronomy.

We discuss the role of Configuration Interaction (CI) and the influence of the number ofconfigurations taken into account in the calculations of nickel and iron spectralopacities provided by the OPAC international collaboration, including statisticalapproaches (SCO, CASSANDRA, STA), detailed accounting (OPAS, LEDCOP, OP, HULLAC-v9) orhybrid method (SCO-RCG). Opacity calculations are presented for a temperature T of 27.3 eVand a density of 3.4 mg/cm3, conditions relevant for pulsating stellarenvelopes.

Laboratory experiments demonstrate that current sheets evolving in magnetized plasmas cangive rise to both flare-type events and generation of energetic plasma jets.

We report laboratory measurements of the Zeeman response of lines in the 0-0 Wing-Fordband of the F-X system (λ ~ 1 μm) of FeH, measuredin magnetic fields 0.3 – 0.5 Tesla. New Landé factors are used to deduce the magneticfield in sunspots from Stokes V profiles recorded at the solar telescope THEMIS. Themagnetic field deduced from atomic lines (Ti, Fe) is slightly higher than that found fromFeH.

The influence of a magnetic field on the broadening of spectral lines and transitionarrays in complex spectra is investigated. The anomalous absorption or emission Zeemanpattern is a superposition of many profiles with different relative strengths, shifts,widths, asymmetries and sharpnesses. The σ and πprofiles can be described statistically, using the moments of the Zeeman components. Wepresent two statistical modellings: the first one provides a diagnostic of the magneticfield and the second one can be used to include the effect of a magnetic field onsimulated atomic spectra in an approximate way.

The optical spectra of L- and T-type dwarfs exhibit a continuum dominated by the farwings of the absorption profiles of the Na 3s-3p and K 4s-4p doublets perturbed bymolecular hydrogen and helium. We examine the K resonance line wing and core with aunified line profile theory and compare to laboratory experiments and observations of thecool brown dwarf ϵ Indi Ba,b.

Stark broadening theories and calculations have been extensively developed for about 50years. The theory can now be considered as mature for many applications, especially foraccurate spectroscopic diagnostics and modelling. This requires the knowledge of numerouscollisional line profiles, especially for very low abundant atoms and ions which are usedas probes for modern spectroscopic diagnostics in astrophysics. Nowadays, the access tosuch data via an on line database becomes essential. STARK-B (http://stark-b.obspm.fr) is a collaborative project between the AstronomicalObservatory of Belgrade and the Laboratoire d’Étude du Rayonnement et de la matière enAstrophysique (LERMA). It is a database of calculated widths and shifts of isolated linesof atoms and ions due to electron and ion collisions (impacts). It is devoted to modellingand spectroscopic diagnostics of stellar atmospheres and envelopes, laboratory plasmas,laser equipments and technological plasmas. Hence, the domain of temperatures anddensities covered by the tables is wide and depends on the ionization degree of theconsidered ion. The STARK-B database is a part of VAMDC (Virtual Atomic and Molecular DataCentre, http://www.vamdc.eu), which is an European Union funded collaborationbetween groups involved in the generation and use of atomic and molecular data. VAMDC aimsto build a secure, documented, flexible and interoperable e-science environment-basedinterface to existing atomic and molecular data.

Energy in the solar system is constantly being converted from one form to another. Oftenthese processes take the form of dramatic events such as solar eruptions or geomagneticstorms with important societal impacts. Understanding energy conversion and magneticstorms is one of the grand challenges facing science and poses a great cultural andscientific puzzle. We plan to use a new modelling approach based on combining state of theart supercomputers with state of the art numerical methods that allow us to capture thekey aspect in energy conversion: the interplay of small and large scales. At the core ofenergy conversion is the ability of macroscopic systems to store and process vast amountsof energy while at the same time requiring microscopic processes at the moment the energyis released. To describe and predict how energy can be stored for long periods and why itis then suddenly released, a complete description down to the level of tracking thetrajectory of single particles is needed.

We review the main results of our previous works, in which we have investigated thedevelopment of the Kelvin-Helmholtz (KH) instability in the transitional regime fromsub-magnetosonic to super-magnetosonic by varying the solar wind velocity, in conditionstypical of those observed at the Earth’s magnetopause flanks. In super-magnetosonicregimes, we show that the vortices produced by the development of the KH instability actas an obstacle in the plasma flow and may generate quasi-perpendicular magnetosonic shockstructures extending well outside the region of velocity shear.

Results are presented from studies of the process of plasma acceleration along thecurrent sheet width under different experimental conditions. The behavior of the neutralcomponent is included in the analysis.

The aim of this work is the analysis of the different transport regimes related to thepropagation in the solar wind of solar energetic particles (SEPs) generated by impulsiveevents like solar flares. A numerical implementation of a Lévy random walk for parallelparticle transport is developed, which allows obtaining superdiffusive transport. Thecomparison between the flows measured by satellites and fluxes extracted from thenumerical simulation, will contribute to a deeper understanding of the mechanismsunderlying the presence of superdiffusive regimes of SEP transport in interplanetarymedium.

It can be argued that all astrophysical jets, from lowly sub-stellar objects such asyoung brown dwarfs to massive black holes at the centre of AGN, are generated by the samebasic physical mechanism. While the nature of that mechanism is still debated, jets fromyoung stars may represent our best chance of deciphering it. There are several reasons forthis statement. First of all they are nearby, thus affording us not only high spatialresolution studies of the “central engine” but also time-resolved analysis of theirkinematics. Moreover as they radiate emission lines, spectroscopy can reveal radialvelocities, temperature, density, ion fraction, etc., along their flow. This wealth ofdata is a challenge to the theorist/computational simulator but also a highly effectivemeans of discriminating between models. In addition, the observations tightly constrainlaboratory experiments. Here, I briefly review what is known about conditions in jets fromyoung stars as a guide to experiments, their generation including their link withaccretion disks, and their evolution from the earliest proto-stellar to pre-main sequencephase.

We investigate the launching process of jets from accretion disks by means ofaxisymmetric MHD simulations. Here, we present results of numerical MHD simulationsinvestigating how magnetic diffusivity and numerical resolution may affect theejection-to-accretion fraction and the asymptotic outflow structure.

Outflows and jets are intimately related to the formation of stars, and play a centralrole in redistributing mass, energy and angular momentum within the core, disk and parentcloud. The interplay between magnetic field and rotation is widely thought to beresponsible for launching and collimating these outflows. Shear induced by differentialrotation along initially poloidal field lines results in an azimuthal component of themagnetic field being generated; the magnetic pressure gradient then accelerates theplasma, and inflates bipolar magnetic cavities within the circumstellar matter. However,the resulting winding of the magnetic field can be potentially disrupted bymagneto-hydrodynamic instabilities. To better understand the role of magnetic fields inshaping these ouflows, a series of experiments on pulsed-power z-pinch machines have beendeveloped. In this talk I will present results related to the formation of jets in youngstellar objects and in the laboratory, and draw a parallel between the two systems.