Projet ANR-07-BLAN-0221 – Dusty Disks : Structure and Evolution of Protoplanetary Disks: a study of the first phases of planet formation
Programme : Blanc (BLANC) 2007
Année de financement : 2007
Coordinateur du projet : CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE RHONE-ALPES SECTEUR ALPES (CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE RHONE-ALPES SECTEUR ALPES)
Partenaires : Centre national de la recherche scientifique; Commissariat à l'énergie atomique et aux énergies alternatives; École normale supérieure de Lyon
Montant : 500000.0 euros
Date de début : 2007
Durée : 48 mois
Résumé : Circumstellar disks are modern day alchemists. They transform dust -  into astronomical gold: planets. Just how exactly remains a mystery -  and the immediate science goals of this proposal aim at answering a -  few of the critical questions astronomers are facing today: what is -  the structure of protoplanetray disks? -  -  Roughly speaking, during the few million years of lifetime of these -  disks, they undergo radical changes in their composition and -  structure. Initially surrounded by an optically thick disk of gas and -  dust supposedly of interstellar composition, processes such as -  photoevaporation, magnetospheric accretion, grain growth, and planet -  formation all act to remove mass (gas and small dust) from the disk as -  it evolves. The circumstellar disks become optically thin and -  eventually disperse entirely, leaving only dust disks produced by 2nd -  generation dust from protoplanetary collisions. As the disk evolves, -  large changes in the disk structure are expected to occur. Disk -  evolution through magnetospheric accretion and photoevaporation will -  move the inner edge of the disk to larger radii, creating disks with -  large inner disk holes. Additionally, one of the key theoretically -  predicted stages of planet formation is dust settling, causing dust -  disks to become geometrically thin. Both processes leave clear -  observational signatures in scattered light images and the spectral -  energy distribution (SED) of the disks, allowing multi-wavelength -  infrared surveys to investigate how far along the planet-formation -  process young stellar objects in the nearest star forming regions have -  gone. -  -  Immediate Scientific Goals:  -  -  Work Package 1 - Data acquisition andvmulti-technique / -  multi-wavelength models: The first step to identify the presence of -  planets in protoplanetray disks is to estimate the disk structure with -  confidence. That is done by using data sets that are as complete as -  possible accross the electromagnetic sprectrum to probe all parts of -  the disks. The present team has expertise ackowledged worldwide in all -  key aspects of the observations of disks. As a consequence we have -  several complete data sets at hands. The mid-IR data will be reduced -  rapidly by partner 3 at the beginning of the project. Similarly, -  near-infrared interferometry will be obtained rapidly with AMBER (by -  partner 1) early on. The next step is to model the data sets as -  coherently as possible, multi-wavelength and multi-technique -  simultaneously and within the framework of a single model. This has -  rarely been done before outside of our group, and certainly not on a -  large scale. We have recently validated a powerful radiative transfer -  code that allows to envisage such an ambitious programme on a large -  scale provided we have access to enough computational power, hence -  opening the path for a new wave of disk models better contrained than -  ever before! -  -  Work Package 2 - Analysis of the model results: These data sets and -  models will allow to address a first suite of scientific -  issues. Because the data sets cover a wide range in central stellar -  masses, the properties of protoplanetary disks will be compared as a -  function of stellar mass. Are they similar or different? Does it have -  an impact on the capacity to form planets? The data sets also cover a -  range in evolutionary status, from the Classical T Tauri phase to -  slightly older times where disks start to dissipate. In these disks we -  will search for the most direct signatures of disk and dust evolution: -  disk inner hole size, dust settling, radial migration, and dust growth -  in order to estimate the timescales for evolution and set contraints -  on the processes at work. In this programme we will push the current -  models further by incorporating radio images tracing larger grains in -  the analysis. We will also try to estimate the dust bulk optical -  properties (e.