Laboratory Astrophysics with lasers Chantal Stehlé LERMA (Laboratoire d’Etudes de la Ma4ère et du Rayonnement en Astrophysique et Atmosphères) This work is partly supported by French state funds managed by the ANR within the InvesBssements d'Avenir programme under reference ANR-11-IDEX-0004-02. Plasma astrophysics see for instance Savin et al. « Lab astro white paper », 2010 Perimeter Methods • Microscopic physical • Experiments processes (opacity, EOS) • Theory, databases • • MulBscale, mulphysics Numerical simulaons • Links to observaons processes (e.g. magne4c reconnecon, shock waves, instabili4es …) Tools • Study of large scale scaled • Medium size lab. processes, (e.g. stellar jets) experiments • Large scale faciliBes (lasers and pinches ) • Super-compung ressources OUTLINE • IntroducBon • Stellar Opacity • EOS for gazeous planets • Scaling • Accreon & Ejecon processes in Young Stars • Conclusion Opacity for stellar interiors From Turck Chièze et al. ApSS 2010 4 Opacity An example of opacity : For a optically thick medium, Hydrogen( Stehlé et al 1993) • LTE is ~ valid -> near blackbody radiaon κν/ρ • The monochromac radiave flux Fν ! is proporBonal to the gradient of rad. Energy and to 1/κν (The radia4on tends to escape from regions where κν is low, ie between lines) hν • The frequency averaged flux <F> is linked to the Rosseland opacity κR. 1 3 dν dB (T) / dT 16 σ T dT 1 ∫ κ ν < F > = and = ν d dB (T) / dT 3 κ R dz κ R ∫ ν ν 5 CEPHEIDS: the enigma Strong periodic (P~ 1 – 50 days) Rela4on P-L : variaons of luminosity L, Teff, and distance calibrator radius. Enveloppe 2 The pulsaon (κ mechanism) log(κR in g/cm ) 2 • in the external part of the stellar envelope 1.5 • linked to an increase of the opacity 1 4 6 -7 -2 3 0.5 10 < T < 10 K (10 < ρ < 10 g/cm ) 0 Hence radiaon is blocked in the internal layers, -> heang -> expansion and beang Core 34 32 30 28 log(External Mass in g ) 2 In the 90’, no code was able Temperature in K, κ in cm /g for M* = 5 M8, Y=0.25, Z=0.08, to reproduce the pulsa6on. Teff= 6400 , 5900 and 5500 K (Bono et al 1999). 6 CEPHEIDS : theory and experiments A synergeEc approach combining : Later on, results from the 1. A revised theoreBcal calculaon Opacity Project -> confirmaEon of the opacity ( Baldnell et al. MNRAS 2005) (OPAL project, Iglesias et al. ApJ 1990) 2. A new calculaon of the stellar structure with the new opaciBes sets (MosKaliK P. et all, ApJ 1992) 3. An experimental measurement of the Fe opacity (Da Silva et al 1992) Principle of an opacity measurement T (hν) = exp (–kν ρ d) Spectrometer : Transmission Difficules • TAMPER ( CH) Avoid the saturaon of the Sample spectra TAMPER ( CH) • Small temperature gradients (uniformity) • LTE Radiave heang X ray backlighBng Revisited Cepheids opacies Exp. Exp. + new calculation ! -> importance of the transitions Δn = 0! (Da Silva et al. PRL 1992) (neglected in the previous opacities). OPAL Iglesias et al. ApJ 1990 Δn=0 -3 3 (3-3) Fe : 8 10 g/cm , 25 eV New opacies introduced in the cepheid model. -> A beler agreement between the observed and calculated pulsaon periods New opaciBes : was obtained 9 Differences for T > 105 K (bumps) (MosKaliK P. et al, ApJ 1992 ) Current work on massive stars: 10-30 eV , 10-3 g/cm3 … smulated by asteroseismology space missions COROT, KEPLER, … PLATO . Further experiments : e.g. on LULI 2000 going for Fe and Ni, in the condiBons of the enveloppes of these massive stars (Loisel et al. 2009, Blenski et al. 2011, Turck- Chièze et al. 2011) Taken from Loisel PhD thesis, 2011 Increasing work on theoreEcal calculaons !! From Turck Chièze et al. ApSS 2010 What about the sun ? Like other stars, the sun oscillates. The heliosismologic observaons (SOHO ) allows to compute the sound speed csound versus radius R. However: if one compares these csound “observed” values with the theoreBcal ones, using revised solar abundances (Asplund et al. ApJ 2005), Results with new opaci4es the disagreement for R /R¤ > 0.5, is larger than with the previous set of abundances (Grevesse & Sauval Sp.Sc.Rev. 1998) (Basu & An4a 2008 , Bahcal et al. 2005, Turck-Chièze et al. 2011, Piau & Couvidat 2011) Results with old opaci4es A « lack » of opacity … ??? Differences between sound velocity between the solar models and the helioseismic results (Bahcall et al 2005) 11 The queson of the solar opacity in the radiave zone ….. in the radiave zone ( below 0.71 R⊙ ) 106 < T ~ <15 106 K, 1 <ρ <150 g/cm3 This requires high energy installaons ! 21 -3 • Sandia ( Z ): Fe at T ~ 150 eV and Ne ~ 7 10 cm (Bailey et al. 2009) -> higher Fe opacity than predicted ! (Bailey et al , Nature 2015 ) 1.2 Opacity x 104 cm2 g-1 Comparison of Fe opacity : 6 0.8 Te = 2.11 10 K, 22 -3 Ne = 3.1 10 cm , 0.4 experimental in black (from Bailey et al., RSI 2015) 0 8 9 10 11 12 Å • NIF : projects for C, N, O at T > 200 eV and ρ > 0.2 g/cm3 (Keiter et al. 2013) Equaon of state for planets See also talk of K. Falk Taken from hp://katjafalk.blogspot.fr/2011/10/my-dphil- research-project.html EOS for gaseous planets & exoplanets P = P(ρ,T) (PV ≠ NkT at high pressure) Mandatory to understand log T (K) the forma4on, evolu4on and 5 H+ structure 4 H atomic of planets and exoplanets. 3 For gaseous planets, H + He (10%) solid -> EOS of Hydrogen and He plays 2 a crucial role Log P(bar) Jupiter, 1 Complex: from molecular Saturn 2 4 6 8 to metallic state From Guillot, Ann. Rev. Earth& Plan. Sc. 2005 around 1 Mbar, 5000 K Jupiter See also talk of K. Falk Interior : a non ideal plasma • From molecular liquid to metallic H • H-He phase separaon (T < 5000 K, P ~few Mbar) 165 -170 K 1Mbar Molecular H2 Inhomogeneous ? 1) An outer helium-poor envelope 8300 -6800 K (He abundance constrained by 2 Mbar spectroscopic measurements of the atmosphere, GALILEO) Metallic H 2) An inner envelope, assumed to coincide with a metallic H region 3) A central dense core 15000 -21000 K of unknown mass and composiBon Rock- ice 40 Mbar core 15 From T. Guillot, Science, 1999 Sll large uncertaines EOS + observaonal constraints -> computaon of the internal structure Mcore/Mplanet Uncertainty concerning the mass of the core : even soluBons with no solid core ( Mcore =0 ) do exist. -> impact on the formaon scenario. Saumon & Guillot 2004 : « Improved astrophysical data will not be sufficient, however it is important to reduce the uncertain4es surrounding the EOS of hydrogen in the 1 to 30 Mbar range ». Similar situaon for Saturn MZ/Mplanet (Helled and Guillot, ApJ 2013) Jupiter structure: core and mass of heavy 16 elements: soluBon fing the observaonal constraints for 5 H- EOS ( Saumon Guillot, ApJ 2004) EOS Experiments • Stac methods, e.g. diamond anvils (P < 1 Mbar, T < 10000 K) • Dynamic methods , e.g. lasers & pinches (P up to 100 Mbar, T up to 105 K) : generaon of a shock wave to compress the maer, determinaon of P, ρ, E, T. • A combinaEon of the two Derivaon of EOS based on Rankine Hugoniot equaons Pusher (u) 3 equaons linking the post shock u, P, (u0=0), P0, quanBBes (u, P, ρ, E) , the velocity ρ, Ε ρ0, E0 of the shock D to the pre-shock condiBons D 3 Taking ρ0 = 1 g/cm , D ~ u = 1 Km/s for P0 ~ 1 bar -> P ~ 100 Mbar 5 unknown parameters : u, P, ρ, E, D => 2 parameters to be measured . 17 Laser experiments on EOS Strong pressure generated by laser ablaon ablator Pusher which drives the pusher. u, T, ρ u0=0 , Pusher : a metal foil and an thin layer of ablator T0, ρ0 on the top of it (ablaon -> rocket launch) D Different diagnoscs, for instance : • VISAR for the shock velocity (D) (Celliers et al RSI, 2001) • OpBcal pyrometry (SOP) or the shock temperature (T) (Cauble et al., ApJS, 2000) • Transverse radiography (D and u) (Cauble et al., ApJS, 2000) • ReflecBvity measurement ( transiBon to metallic state ) (Knudsen et al., Sc. 2015) • X-ray Thomson scaering (ne, te, Ti, Z) (FalK et al. PRE, 2013) Difficules : • Uniformity and planarity of the shock -> (phase plate to smooth laser beam) • Staonarity • Control of the iniBal condiBons : no preheang 18 D2 EOS laser experiments In 2000, work on cryogenic D2 by Cauble et al. (ApJS 127, 267, 2000) at NOVA at the high pressure , high temperature, insolator – metal transmission NOVA drive beam Shock front 527 nm, 3 1014 W/cm2, few ns Interface Pusher : Al + layer of CH (ablator) Be window Time in ns BacklighBng Radiography 0 100 200 300 400 500 Distance in microns Pyrometry => T U , U 19 p s Design of the cryogenic cell to measure properBes of the EOS of Deuterium Extensive study, in theory and experiments 300 250 200 D / H 150 2 2 100 Pressure in GPa Pressure in GPa 50 10 100 1000 3 4 5 6 0 2 3 4 5 6 Compression ρ/ρ0 Compression ρ/ρ0 Calculated Hugoniots for D star4ng with the 2 Principal Hugoniot of D2 and H2 : experiments ini4al density of 0.717 g/cm3 (OMEGA ) and a selecon of theore4cal results (from Hicks et al.. PRB 2009) (from Loubeyre et al. PRB 2012) Too large uncertainBes in the measurements to constraint the various theoreBcal models 20 Similaries and Scaling Aircrao in a wind tunnel at ONERA 21 HH47 seen by HST Similaries (EsirKepov & Bulanov, 2012) or, how to make the bridge between astrophysics and experiments ? Absolute similarity : same equaons, same dimensionless quanBBes, and also scaled iniBal condiBons (rather difficult ) Approximate similarity : only basic parameters are reproduced (common situa4on) JETS - configuraon simulaon: global geometry + some physical processes - process simulaon: local physical processes in astrophysical condi4ons.