Benoit Commerçon, Marc Joos, Anaelle Maury, Jacques Masson

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1 Benoit Commerçon, Marc Joos, Anaelle Maury, Jacques Masson
Des Galaxies aux planètes : le milieu interstellaire Comment la simulation numérique aide à comprendre la formation des étoiles et des disques protoplanétaires Patrick Hennebelle pour le PCMI Dahbia Talbi, Jean-Hugues Fillion, Valentine Wakelam, Alexandre Faure, Franck Le Petit Benoit Commerçon, Marc Joos, Anaelle Maury, Jacques Masson Edouard Audit, Andréa Ciardi, Sébastien Fromang, Romain Teyssier, Gilles Chabrier, Philippe André

2 Qu’est-ce que le PCMI ? Quels sont ses objectifs ?
La formation des étoiles et des planètes L’émergence de la complexité Un écran à soustraire

3 Large scale structures
Interstellar Cycle Planets Dense Cores Accretion discs Hot Ionised Gas STARS Heavy Elements Kinetic energy Radiation Cosmic Rays Warm Ionised Gas Warm Neutral Gas Cold Neutral Gas Molecular Gas

4 ECOLE EVRY SHATZMAN 2012 ees2012.ens.fr

5 In the Interstellar Medium:
Radiation ≈ Thermal ≈ Kinetic ≈ Cosmic Rays ≈ Magnetic ≈1 eV cm-3 => Energy equipartition => Strong coupling between several physical processes => Difficult to simplify and isolate the problems => Slow progress

6 Performing global Simulations
Simulating whole galaxies Simulating parts of galaxies Bournaud et al. 2010 de Avillez & Breitschwerdt 2005 Performed with RAMSES PRACE+ERC project

7 Large scale structures
Interstellar Cycle Planets Dense Cores Accretion discs Hot Ionised Gas STARS Heavy Elements Kinetic energy Radiation Cosmic Rays Warm Ionised Gas Warm Neutral Gas Cold Neutral Gas Molecular Gas

8 The 2-phase model Wolfire et al. 95
Thermal equilibrium curve (Field et al. 69, Wolfire et al. 95) WNM CNM Unstable Wolfire et al. 95 Field 65: performs linear stability analysis of the radiatively cooling fluid equations. Obtains the isobaric criteria for instability:

9 Turbulence within a bistable fluid
(Koyama & Inutsuka 02,04, Kritsuk & Norman 02, Gazol et al. 02, Audit & Hennebelle 05, Heitsch et al. 05, 06, Vazquez-Semadeni et al. 06) -Forcing from the boundary -Statistical stationarity reached -complex 2-phase structure -cnm very fragmented -turbulence in CNM is maintained by interaction with WNM 20 pc 25002 Audit & Hennebelle 05

10 3D simulations 12003 Intermediate behaviour between 2-phase and polytropic flow

11 For the Formation of Structures
Importance of Cooling For the Formation of Structures Formation of a molecular cloud : -with Cooling -Isothermal Converging flow 50 pc

12 Gas-phase chemical modeling
A + B → C + D Model parameters : -Temperature (K) -Density (cm-3) -Elemental abundances UV, X-rays, cosmic-rays fields -Chemical networks KIDA Kinetic database for Astrochemistry Computation of the chemical abundances : dni/dt =  klj nlnj - ni  kij nj Production Destruction k : reaction rate coefficients A large community of French chemists and physicists, theoreticians and experimentalists are involved in the determination of accurate k (Bordeaux, Dijon, Montpellier, Paris, Rennes)

13 Astrochemical modelling
Kinetic Data Base (KIDA) HY=EY QCT, RRKM, TST ……. Measurment at low T and P k (T) CRESU

14 Large scale structures
Interstellar Cycle Planets Dense Cores Accretion discs Hot Ionised Gas STARS Heavy Elements Kinetic energy Radiation Cosmic Rays Warm Ionised Gas Warm Neutral Gas Cold Neutral Gas Molecular Gas

15 Hennebelle et al. (2008), Klessen & Hennebelle (2010)
Flow of WNM (density 1cc), velocity 20km/s each side, initial magnetic field 5G, gravity included Hennebelle et al. (2008), Klessen & Hennebelle (2010)

16 Internal clump velocity dispersion
(density > 2500 cm-3) saR0.5 Falgarone 2000 Compatible with Larson law =>is turbulence within GMC driven from outside ? Klessen & Hennebelle (2010)

17 Influence of supernovae explosions within molecular clouds
Iffrig & Hennebelle in prep 2012

18 Large scale structures
Interstellar Cycle Planets Dense Cores Accretion discs Hot Ionised Gas STARS Heavy Elements Kinetic energy Radiation Cosmic Rays Warm Ionised Gas Warm Neutral Gas Cold Neutral Gas Molecular Gas

19 The core mass function Alves et al. 2007 Konyves, André et al. 2010
(Motte et al. 1998, Testi & Sargent 1998, Alves et al. 2007, Johnstone et al , Enoch et al. 2008, Simpson et al. 2008) Alves et al. 2007 Konyves, André et al. 2010

20 Extending Press-Schecter (1974) approach to the supersonic turbulent case
Principles of Press-Schecter analysis Used in cosmology to predict the mass spectrum of DM haloes: =>very successful -consider a spectrum of density fluctuations (Gaussian in the cosmological case) characterized by its powerspectrum and smooth it at scale R -setup a criterion to decide which perturbations have to be considered (collapse time should be smaller than the age of the universe) -sum over the corresponding fluctuations In the case of Molecular clouds (Padoan et al. 1997, Hennebelle & Chabrier 2008, 2009, 2011, Hopkins 2011, 2012) -assume that the density PDF is log-normal -the power-spectrum of log r is close to Kolmogorov -consider a uniform density threshold -consider self-gravitating structures

21 Comparisons with numerical simulations
Hennebelle & Chabrier 2009 Comparison with numerical simulations from Jappsen et al with gravity Schmidt et al. 2010 Comparison with high resolution numerical simulations without gravity No free parameter

22 Large scale structures
Interstellar Cycle Planets Dense Cores Accretion discs Hot Ionised Gas STARS Heavy Elements Kinetic energy Radiation Cosmic Rays Warm Ionised Gas Warm Neutral Gas Cold Neutral Gas Molecular Gas

23 A collapse calculation (zoom onto the central part)
(Hennebelle & Fromang 2008, Commerçon et al. 2010, Joos et al. 2012) 1 solar mass slowly rotating core 300 AU XY hydro XY MHD =2 B, w XZhydro XZ MHD =2 B, w

24 Comparison of the PdBI maps with MHD simulations
Hydrodynamical simulations produce too much extended (+ multiple) structures if compared to the observations. MHD simulations ? Taurus Perseus Hennebelle & Fromang (2008) Hennebelle & Teyssier (2008) MHD simulations : produce PdB-A synthetic images with typical FWHM ~ 0.2’’ - 0.6’’ Similar to Class 0 PdB-A sources observed ! need B to produce compact, single PdB-A sources. Maury et al. 2010 White dashed : 3sigma level. Thick black : 5sigma level

25 Hincelin U. , Commerçon B. , Wakelam V. , Hersant F. , Guilloteau S
Hincelin U., Commerçon B., Wakelam V., Hersant F., Guilloteau S., Aikawa Y. en préparation Chimie 3D de l’effondrement des cœurs denses - formation des disques protoplanétaires Chimie gaz-grain NAUTILUS Hersant et al Hincelin et al. 2011 CO(gaz)/H x(UA) z(UA) y(UA) Effondrement 3D (RMHD) RAMSES Teyssier 2002 Fromang et al Commerçon et al. 2011 T(K) 30 100 300 50 -50 -100 log n(cm-3) 13 12 11 10 t=4.104ans Chimie 3D

26 Direct excitation of CO
Photodesorption UV d’un analogue de glace interstellaire : Première étude expérimentale de la dépendence en longueur d’onde. 5 Photodésorption de CO (15 K) molecule/photon δ Expérience Ultra-vide & utilisation du rayonnement synchrotron (SOLEIL) UV photon ( nm) CO desorption Absorption UV est Méthode de référence recommandé par le BIPM Incertitude se voit dans les mesures Direct excitation of CO CO Au, 18 K Fayolle et al. APJ 2011 Compréhension du mécanisme microphysique Taux de photodésorption dans différents champs de rayonnement

27 Bases de données théoriques pour le MIS
PDR Data Base (LUTH / MIS) Modèles de nuages interstellaires pour Herschel, IRAM, ALMA, VLT, HST, FUSE, ... Interprétation «ordre 0» ou préparation d’observations densité de colonne de centaines d’espèces chimiques intensités de raies, spectres structures des nuages Application : milieu diffus, régions de formation d’étoiles, milieu intergalactique, ... Starformat (LERMA / ENS) Simulations MHD du gaz interstellaire Formation des nuages, coeurs denses, ... Propriétés de la turbulence Propriétés des coeurs denses distribution masse, vitesse, ... Post-traitement fournissent observables Développement international

28 Conclusions La formation des étoiles et des planètes sont des processus intimement liés qui sont : -multi-échelles -multi-physiques impliquant la synergie entre : -observations -théories non-linéaires -simulations numériques -développement et maintien de codes -expériences de laboratoire -bases de données Des progrès importants ont été réalisés (IMF, SFR, fragmentation). ALMA ouvre de grandes perspectives.

29 Column density Magnetic field Density cut Temperature
Although the cloud appears as a single phase entity in projection, its structure is not very different from the CNM/WNM structure. Clumps are bounded by WNM which provides them a confining pressure. Density cut Temperature