Projet ANR-10-JCJC-0504 – DiskEvol : Formation et évolution des systèmes planétaires
Programme : JCJC : Sciences de l'information, de la matière et de l'ingénierie : Sciences de l’univers (JCJC SIMI 5)
Année de financement : 2010
Coordinateur du projet : Monsieur Christophe PINTE (CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE RHONE-ALPES SECTEUR ALPES)
Partenaires : Laboratoire d'Astrophysique de Grenoble
Montant : 150000.0 euros
Durée : 36 mois
Résumé : Formation et evolution des systemes planetaires .
.The main objective of DiskEvol is to bridge the gap between two research fields in the study of protoplanetary disks. The first focuses in the millimeter regime, particularly molecular emission lines, to derive the kinematics and abundances of the gas within the disk. The focus of the second is on the optical and infrared observations, which study in detail the dust component. The individual information from the dust and gas components is almost never used conjointly, hence limiting our ability to precisely understand the structure and evolution processes of disks. To overcome this limitation, it is necessary to model the gas and dust observations as coherently as possible in the framework of a single model. We have developed one of the most powerful radiative transfer codes: MCFOST, which can calculate both continuum and line transfer coherently. Through DiskEvol, we will build a team that will perform a systematic, simultaneous modelling of the dust and gas observations of disks using MCFOST, in particular the observations from the Herschel project GASPS, so as to characterise the physical and chemical conditions within disks, and from this assess, the main evolution processes of disks and from this assess, the main evolution processes of disks.	Two parallel and complementary approaches will be followed: 1) a statistical comparison of the observations of the whole GASPS sample with large grids of models and 2) a detailed fitting of a selected sample of sources with high-quality datasets combining line observations, SEDs and resolved continuum maps (scattered light images and/or (sub-)mm visibilities). This work will rely on numerical developments to couple the chemistry and radiative transfer codes available at IPAG : ProDiMo and MCFOST.
.The research program is organised in 3 main tasks :Task 1: Database of observations and models for the GASPS project The goal is to provide complementary data in the millimeter regions for the GASPS source and to make this data quickly available within the consortium. The second objective is to build tools that will allow detailed interpretation of these data sets. We will compute a grid of radiative transfer models with MCFOST (SEDs and line fluxes for the lines observed by GASPS) over a wide range of spectral types and disk parameters. The ultimate objective of this first task is to build a uniform and easy-to- access set of data (observations and models) that will be intensively used for interpretation. Task 2: Analysis of the GASPS results: a dust and gas inventory of disks We will interpret the observed signatures of both the dust and gas with respect to the aforementioned grid of models. The statistical comparison of the grid of models with the observational data sets will offer us the ability to interpret observational trends in terms of model parameters. We will search for the most direct signatures of disk evolution: inner hole size, gas mass and chemical state, dust growth and settling in order to estimate the timescales for evolution and set constraints on the processes at work.Task 3: A complete view of the dust structure and gas chemistry in disks To characterise the processes by which disks evolve, the statistical results of task 2 must be completed by model fitting of a selected sample of representative sources, which will serve as references for the global analysis. We will precisely analyse CO molecular maps of this selected sample of disks. This will allow us to constrain the kinematics and dynamics of the gas, to measure the gas scale height and temperature and compare them to the dust ones, as well as analyse water molecule lines to constrain the physical conditions of the molecular gas in the planet forming region of protoplanetary disks.
Résumé de la soumission : La majorité de nos connaissances sur les disques protoplanétaires provient d'études de la composante de poussière des disques (par exemple,distributions spectrales d'énergie (SED), images en lumière diffusée, cartes en émission thermique), alors que la poussière ne représente qu’unpourcent de la masse initiale d’un disque protoplanétaire. A l’opposé, la composante dominante en masse, le gaz, est beaucoup plus difficile àobserver. Combiner les informations sur la poussière et le gaz est particulièrement intéressant pour comprendre l’évolution des disques. Le télescopespatial Herschel, qui doit être lancé au mois d’avril cette année, va ouvrir une fenêtre de longueurs d’onde inexplorée, l’infrarouge lointain, et offriraccès à des observations du gaz dans les disques de haute qualité. J’ai été invité à participer au programme clef “GAS in Protoplanetary Systems”(GASPS) dans le cadre du temps ouvert. Ce programme va observer dans le continu (poussière) et dans les raies (gaz) de [CII], [OI] et de lamolécule d’eau, un échantillon non biaisé de 240 étoiles jeunes, couvrant une large gamme de masses stellaires et l’ensemble de la période deformation planétaire.Le projet DiskEvol va s’attaquer au problème complexe d’ajouter de façon cohérente les contraintes provenant du gaz, en particulier celles provenantdes observations d’Herschel, à nos études de la phase de poussière. L’interprétation des observations du gaz est compliquée à cause du nombreimportant de processus physiques en jeu: chimie, excitation et destruction des molécules, condensations sur les grains, par exemple. Mais ce typed’étude est particulièrement important car la dissipation du gaz, initialement abondant après la formation de l’étoile, limite le temps disponible pourformer des planètes géantes, contrôle la dynamique des corps planétaires de toute taille pendant leur formation et détermine l’architecture finale dusystème planétaire.Le programme va reposer sur 1) la préparation d’une base de données incluant observations et modèles pour le projet GASPS, au moyen d'observationscomplementaires pour GASPS dans le millimetrique et la génération de grilles de modèles de transfert de rayonnement (SEDs et flux dansles raies). Ce travail initial va permettre 2) une analyse détaillée résultats du programme GASPS grâce à une comparaison statistique desobservations avec les prédictions de la grille de modèles. Cette étude globale du large échantillon de disques observés par GASPS sera 2) étendueet complétée par des modélisations plus fines et détaillées de quelques sources représentatives. Nous allons obtenir une vue complète de lastructure de la poussière et de la chimie du gaz de ces sources, au moyen d’interprétations simultanées des observations dans le continu, de cartesrésolues dans les transitions moléculaires de faible niveau du CO, ainsi que des observations de suivi à haute résolution spectrale avec l’instrumentHIFI, à bord d’Herschel.DiskEvol va fournir un inventaire sans précédent du gaz et de la poussière dans les disques protoplanétaire, transformant notre compréhension del’évolution des disques en adressant des questions clefs sur les temps caractéristiques et mécanismes par lesquels la poussière et le gaz évoluentdans les disques. En outre, la valeur à long terme des résultats de DiskEvol revêt une importance exceptionnelle dans l’aire d’ALMA et de JWST.
Résultats : Progress has been on all aspects of the project and accordingly to
 the initial plan. 28 refereed publications have resulted from this work so far.
Task 1 : 
 - the anciallary data sets from IRAM have been reduced and published  (Mathews et al 2012).
 - A new collaboration on the analysis and publication of Herschel data on a sample of brown dwarfs (Harvey et al 2011, 2012) has been initiated.
 - A new program to detect edge-on disk with HST has been initiated, resulting  in 8 discoveries
 - The program to collect interferometric data with PIONIER has started as well as its analysis with complementary data, for instance from Herschel DIGIT.
Task 2 :
 - New modelling tools have been set up to compare the observational data with  models in a very efficient way (parallel genetic and MCMC algorithms which  have been tailored to the problem).
 - Study of the results of the DENT grid : establishing diagnostics for the gaz  in disks.
 - Modelling of the SEDs of the Taurus objects (Pinte et al, in prep.) and
 Upper Sco.
 - The analysis of the statististical results of GASPS has led to several
 publications : for Herbig Ae stars (Meeus et al 2012), the detection of water  in the disks in Taurus (Riviere et al 2012), the comparison of the emission  from disks and jets (Podio et al 2012), the detection of CH+ around HD 100546 (Thi et al 2011).
Task 3 :
 - Detailed modelling of the disks surounding  TW Hydra,  HD163296,
 HK Tau, T Cha, HD 100546, HD 181327, HD 172555/
 - Developping the tools to study the CO ro-vibrational lines  (HD135344 B,  Carmona et al 2013).
 - Studying the effect of the water chenistry and of the details of radiative transfer on water emission lines (Kamp et al 2013)
 - Interfacing the mcfost code with the LIDT code from CEA/Saclay (S. Charnoz)  and phantom code (D. Price, G. laibe)  to study the evolution of dust grains  in disks.
Perspectives : The studies developped in DIskEvol will become more influential with the advent of the ALMA interferometer and JWST space telescopes, that will complement Herschel observations at both longer and shorter wavelengths. ALMA is providing images and velocity maps at high spatial resolution (and not only integrated quantities as in the case of Herschel). It probes the density, temperature and abundance gradients non only in the external parts of disks but also closer to the star, at spatial scales of the order of 10 AU. Er are now at a point where we can predict, using the aforementioned RT / chemistry codes (MCFOST and ProDiMo), the emission maps (continuum and molecular lines), as they will be seen by ALMA, and to determine the spatial dependence of the physico-chemical conditions. JWST’s imaging and spectroscopy capabilities will complement Herschel observations at shorter wavelengths, and in particular will determine more precisely than Spitzer the constituents of the dust grains, it will observed the highly excited hot CO (ro-vibrational bands around 2.3 and 4.6 µm) in the central regions of the disks, and will study organic molecules that are important for life to develop.
In particular, the GASPS sources, for which we will have detailed models, are very likely to be priority targets for ALMA and JWST. We will use the results of the aforementioned tasks to make predictions regarding the observable consequences of gas and dust evolution, and planet formation. These aspects are key drivers for both instruments and our calculations will provide the best estimates, closest to reality, for signatures of evolution in disks.
Publications et brevets : Howard et al.,  2013,  ApJ,  776,  21
Mathews, Pinte, Duchene, Williams, and Menard,  2013,  A&A,  558,  A66
de Gregorio-Monsalvo et al.,  2013,  A&A,  557,  A133
Thi et al.,  2013,  A&A,  557,  A111
Canovas et al.,  2013,  A&A,  556,  A123
Riviere-Marichalar et al.,  2013,  A&A,  555,  A67
Dent et al.,  2013,  PASP,  125,  477
Olofsson et al.,  2013,  A&A,  552,  A4
Podio et al.,  2013,  ApJl,  766,  L5
Cieza et al.,  2013,  ApJ,  762,  100
Gonzalez, Pinte, Maddison, Menard, and Fouchet,  2012,  A&A,  547,  A58
Riviere-Marichalar et al.,  2012,  A&A,  546,  L8
Podio et al.,  2012,  A&A,  545,  A44
Harvey et al.,  2012,  ApJ,  755,  67
Meeus et al.,  2012,  A&A,  544,  A78
Lebreton et al.,  2012,  A&A,  539,  A17
Riviere-Marichalar et al.,  2012,  A&A,  538,  L3
Tilling et al.,  2012,  A&A,  538,  A20
Mathews et al.,  2012,  ApJ,  745,  23
Harvey et al.,  2012,  ApJl,  744,  L1
Cieza et al.,  2011,  ApJl,  741,  L25
Melis et al.,  2011,  ApJl,  739,  L7
Kamp et al.,  2011,  A&A,  532,  A85
Patience et al.,  2011,  A&A,  531,  L17
Tatulli et al.,  2011,  A&A,  531,  A1
Thi et al.,  2011,  A&A,  530,  L2
Olofsson et al.,  2011,  A&A,  528,  L6
McCabe et al.,  2011,  ApJ,  727,  90