Periodic Reporting for period 1 - Dust2Planets (From Dust to Planets: A Novel Approach to Constrain Dust Growth and the Planet Forming Zone in Disks)
Reporting period: 2022-09-01 to 2025-02-28
Exoplanets are frequent around Solar-like stars, as shown by Large Surveys. More than 7000 are known today... They are formed by the growth of dust and accumulation of
gas contained in protoplanetary disks surrounding young stars. To form planets, the classic Core-Accretion scenario is the main framework
today, but it appears to be too slow given the short lifetimes of disks. Theoretical additions to the Core-Accretion scenario exist to speed it up. They
all hypothesize that disks contain a massive, dense, and flat layer of pebbles in the midplane. The validation of these scenarios will be
impossible as long as the disk properties remain uncertain. The first objective of this project is to provide the first direct observational
constraints (mass, vertical extent, radius) for this midplane pebble layer. Specifically, an original imaging programme for Edge-On
disks will be combined with dedicated hydrodynamical models of vertical dust settling, taking into account dust evolution and dust-
gas dynamics. The second objective is to identify the shape of dust in young disks and pin down their growth
mechanisms. This major advance is also crucial because the structure/shape of dust governs the dust-gas dynamics (via collision and drag cross-
sections) as well as the scattering properties needed to compare imaging data and models. To meet this goal, we will extract the scattering properties
(phase function, polarisation) from high resolution images and use a unique micro-wave analogy experiment. Complex analog particles
will be fabricated, measured in the lab, and compared with data to ultimately reveal the structure of dust in disks. All these results, combined in
the final objective, will lead to a major leap towards a deep understanding of dust growth and early planet assembly in protoplanetary
disks. Dust2Planets has the potential to overcome two long-standing obstacles in early planetesimal assembly: how dust overcomes the
radial-drift and fragmentation barriers to form planetesimals.
gas contained in protoplanetary disks surrounding young stars. To form planets, the classic Core-Accretion scenario is the main framework
today, but it appears to be too slow given the short lifetimes of disks. Theoretical additions to the Core-Accretion scenario exist to speed it up. They
all hypothesize that disks contain a massive, dense, and flat layer of pebbles in the midplane. The validation of these scenarios will be
impossible as long as the disk properties remain uncertain. The first objective of this project is to provide the first direct observational
constraints (mass, vertical extent, radius) for this midplane pebble layer. Specifically, an original imaging programme for Edge-On
disks will be combined with dedicated hydrodynamical models of vertical dust settling, taking into account dust evolution and dust-
gas dynamics. The second objective is to identify the shape of dust in young disks and pin down their growth
mechanisms. This major advance is also crucial because the structure/shape of dust governs the dust-gas dynamics (via collision and drag cross-
sections) as well as the scattering properties needed to compare imaging data and models. To meet this goal, we will extract the scattering properties
(phase function, polarisation) from high resolution images and use a unique micro-wave analogy experiment. Complex analog particles
will be fabricated, measured in the lab, and compared with data to ultimately reveal the structure of dust in disks. All these results, combined in
the final objective, will lead to a major leap towards a deep understanding of dust growth and early planet assembly in protoplanetary
disks. Dust2Planets has the potential to overcome two long-standing obstacles in early planetesimal assembly: how dust overcomes the
radial-drift and fragmentation barriers to form planetesimals.
Objective 1: Analysis and Modelling of Data
- Task 1.1.1: Reduction and Analysis of ALMA Data for Ringed-Disks
The data modeling part of this task is complete, and analysis is ongoing. The main result of this task is the confirmation that millimeter-sized grains in ringed disks are concentrated in a flat midplane layer. This finding supports earlier suggestions made through our analysis of HL Tau data in 2018, marking an early success for the Dust2Planets project.
Task 1.1.2: Reduction and Combined Analysis of ALMA, HST, and JWST Data for Edge-On Disks
This task involves the analysis of data from the James Webb Space Telescope (JWST), ALMA, and the Hubble Space Telescope (HST). The PI was awarded two JWST programs in Cycles 1 and 2. Data from Cycle 1, covering four targets, have been analyzed and published, with the results appearing in four papers. Analysis of Cycle 2 data (covering 11 targets) is ongoing.
In addition, the edge-on disk PDS 453 was recently modeled as well, using data from HST, SPHERE, and spectroscopic observations to quantify water ice content in the disk.
Task 1.2: Hydrodynamical Models and Predictions
This task has just begun. Although this represents a slight delay, the results are expected well before the end of the project, with no anticipated impact on the overall scientific output. This task focuses on creating hydrodynamic models to predict the evolution (growth, destruction,dynamics) of dust in protoplanetary disks, an important step for understanding disk dynamics and early planet formation.
Objective 2: Analog Fabrication and Diffusion Measurements
Task 2.1: Fabrication of Analogues and Microwave Measurements
Fabrication and measurent of several 3D-printed analogs of dust particles using microwave measurements is underway. In 2024, the anechoic chamber was completely refurbished. This improvement, which was not initially planned, has significantly enhanced the performance of the instrumental set-up. Measurements have just resumed , at the time of writing. While the set-up was being upgraded, several analogs of different shapes were fabricated (ice coated fractals, random gaussian spheres, ...). As part of the collaboration, new materials for 3D printing were also developed that are better matched to the expected refractive indices of astronomical dust material (silicates, carbonaceous coumpounds).
Task 2.2: Scattering Phase Function and Polarization for Young Disks
A new extraction software was developed from scratch to extract scattering phase functions in total intensity and linear polarization from astronomical disk images. The software, which is now available publicly on GitHub, allows for the fast and efficient analysis of scattering properties, with the addition of proper error handling and a user-friendly interface. We will now focus on analyzing the scattering phase functions from more than 25 individual disks using data from the SPHERE science archive, with a focus on young disks.
Most Significant Achievements
JWST Time Allocation and Papers
Securing JWST time as a principal investigator was a significant achievement in itself. The four scientific papers published from the data of JWST Cycle 1 represent substantial advances in understanding vertical dust settling in protoplanetary disks.
Development of Scattering Phase Function Extraction Software
The creation of a software tool by Maxime Roumesy to extract scattering phase functions from raw images is a key achievement. This tool allows for quick, accurate analysis and is now available for use by the wider scientific community.
Multi-Wavelength Approach to Disk Studies
The project has focused on multi-wavelength studies of dust in disks, covering optical, infrared, and thermal emissions. This combination of different data types has already provided insights into disk structure. However, the analysis of gas content, especially in edge-on disks, promises to enhance this understanding. The project has prepared a large ALMA program to study molecular gas lines in nine edge-on disks, with data already secured for the first phase.
ALMA Large Program Selection
A major achievement is the recent allocation of an ALMA large program that we lead. The proposal was ranked first among all submitted proposals in Cycle 11. This program will allow for the measurement of molecular gas lines in nine edge-on disks, providing critical data for understanding disk temperature and density stratifications. This initiative is expected to significantly enhance the overall understanding of vertical settling in disks.
- Task 1.1.1: Reduction and Analysis of ALMA Data for Ringed-Disks
The data modeling part of this task is complete, and analysis is ongoing. The main result of this task is the confirmation that millimeter-sized grains in ringed disks are concentrated in a flat midplane layer. This finding supports earlier suggestions made through our analysis of HL Tau data in 2018, marking an early success for the Dust2Planets project.
Task 1.1.2: Reduction and Combined Analysis of ALMA, HST, and JWST Data for Edge-On Disks
This task involves the analysis of data from the James Webb Space Telescope (JWST), ALMA, and the Hubble Space Telescope (HST). The PI was awarded two JWST programs in Cycles 1 and 2. Data from Cycle 1, covering four targets, have been analyzed and published, with the results appearing in four papers. Analysis of Cycle 2 data (covering 11 targets) is ongoing.
In addition, the edge-on disk PDS 453 was recently modeled as well, using data from HST, SPHERE, and spectroscopic observations to quantify water ice content in the disk.
Task 1.2: Hydrodynamical Models and Predictions
This task has just begun. Although this represents a slight delay, the results are expected well before the end of the project, with no anticipated impact on the overall scientific output. This task focuses on creating hydrodynamic models to predict the evolution (growth, destruction,dynamics) of dust in protoplanetary disks, an important step for understanding disk dynamics and early planet formation.
Objective 2: Analog Fabrication and Diffusion Measurements
Task 2.1: Fabrication of Analogues and Microwave Measurements
Fabrication and measurent of several 3D-printed analogs of dust particles using microwave measurements is underway. In 2024, the anechoic chamber was completely refurbished. This improvement, which was not initially planned, has significantly enhanced the performance of the instrumental set-up. Measurements have just resumed , at the time of writing. While the set-up was being upgraded, several analogs of different shapes were fabricated (ice coated fractals, random gaussian spheres, ...). As part of the collaboration, new materials for 3D printing were also developed that are better matched to the expected refractive indices of astronomical dust material (silicates, carbonaceous coumpounds).
Task 2.2: Scattering Phase Function and Polarization for Young Disks
A new extraction software was developed from scratch to extract scattering phase functions in total intensity and linear polarization from astronomical disk images. The software, which is now available publicly on GitHub, allows for the fast and efficient analysis of scattering properties, with the addition of proper error handling and a user-friendly interface. We will now focus on analyzing the scattering phase functions from more than 25 individual disks using data from the SPHERE science archive, with a focus on young disks.
Most Significant Achievements
JWST Time Allocation and Papers
Securing JWST time as a principal investigator was a significant achievement in itself. The four scientific papers published from the data of JWST Cycle 1 represent substantial advances in understanding vertical dust settling in protoplanetary disks.
Development of Scattering Phase Function Extraction Software
The creation of a software tool by Maxime Roumesy to extract scattering phase functions from raw images is a key achievement. This tool allows for quick, accurate analysis and is now available for use by the wider scientific community.
Multi-Wavelength Approach to Disk Studies
The project has focused on multi-wavelength studies of dust in disks, covering optical, infrared, and thermal emissions. This combination of different data types has already provided insights into disk structure. However, the analysis of gas content, especially in edge-on disks, promises to enhance this understanding. The project has prepared a large ALMA program to study molecular gas lines in nine edge-on disks, with data already secured for the first phase.
ALMA Large Program Selection
A major achievement is the recent allocation of an ALMA large program that we lead. The proposal was ranked first among all submitted proposals in Cycle 11. This program will allow for the measurement of molecular gas lines in nine edge-on disks, providing critical data for understanding disk temperature and density stratifications. This initiative is expected to significantly enhance the overall understanding of vertical settling in disks.
The results from the combined analysis of JWST, HST, ALMA data provide the best constraints to date about the amplitude of vertical settling. This field of research is quickly expending folliwing our first results. Recall that vertical settling is necessary to increase the concentration of dust in the disk midplane, itself necessary to ensure rapid and efficient planet formation. Understanding these mechanims is the ultimate goal of Project D2P (From Dust 2 Planets). The project, and the corresponding results, are clear leading the field.