BLANC - Blanc

Structure and Evolution of Protoplanetary Disks: a study of the first phases of planet formation – Dusty Disks

Submission summary

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.g., opacity, albedo) as well as scattering properties - (size distribution, phase function, and maybe shape of particle...

Project coordination

Francois MENARD (Organisme de recherche)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

COMMISSARIAT A L'ENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES - CENTRE D'ETUDES NUCLEAIRES SACLAY

Help of the ANR 500,000 euros
Beginning and duration of the scientific project: - 48 Months

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