Exploring the pristine conditions for transforming interstellar dust into planetesimals

Projektinformationen

PEBBLES

ID Finanzhilfevereinbarung: 101098309

DOI

10.3030/101098309

EK-Unterschriftsdatum 14 Juli 2023

Startdatum 1 August 2023

Enddatum 31 Juli 2028

Finanziert unter

• European Research Council (ERC)

Gesamtkosten

€ 2 444 587,50

EU-Beitrag

€ 2 444 587,50

Koordiniert durch

AGENCIA ESTATAL CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS
Spain

Periodic Reporting for period 1 - PEBBLES (Exploring the pristine conditions for transforming interstellar dust into planetesimals)

Berichtszeitraum: 2023-08-01 bis 2026-01-31

Zusammenfassung vom Kontext und den Gesamtzielen des Projekts

The formation and properties of exoplanetary systems is a fascinating question, which has been at the heart of our quest to define mankind and the conditions for life to develop in a broader context.

Recent astronomical observations have deeply modified our paradigm of planet formation, as they suggest the so-called "proto-planetary" disks surrounding T-Tauri stars may actually already host planets. Moreover, we have obtained some of the first observational clues that the dust particles contained in the pristine disk-forming reservoirs that are the embedded protostars may already have significantly evolved from the submicrometer dust populating the interstellar medium. These results suggest that dust evolves significantly already during the first 0.5 Myrs of the star formation process, and highlight the prime importance of understanding the properties and evolution of dust in young protostars.

The PEBBLES project aims at developing a thorough methodology to characterize the properties of dust in embedded protostars, where we know the star and its disk are forming concomitantly. Using an innovative methodology combining cutting edge observational datasets, dust models and numerical models, we aim to transform our understanding of:
1) The nature of the dust incorporated in the youngest disks, a key for models of disk evolution towards planetary systems
2) The processes at work for dust evolution in young protostars, from envelopes to disk scales
3) The efficiency of magnetic fields to couple to the star/disk forming material, and set the disk properties

By shedding light on early dust evolution, PEBBLES will not only address one of the oldest and most challenging question regarding the initial conditions for planet formation in disks around solar-type stars, but also provide new insight to the conditions reigning and their impact on physical processes during the main accretion stage, during which stars acquire most of their properties.

Arbeit, die ab Beginn des Projekts bis zum Ende des durch den Bericht erfassten Berichtszeitraums geleistet wurde, und die wichtigsten bis dahin erzielten Ergebnisse

The PEBBLES project has focused on obtaining observations and develop models to characterize the properties of dust grains in yourg embedded protostars, at the epoch disks are forming and evolving towards planet-forming disks.
Regarding models, we have successfully developed both a dynamical model to follow dust solid particles evolution (aggregation into larger particles) during the collapse of protostellar dense cores, and structural models to predict the optical properties of aggregate dust grains predicted by the dynamical models.
These two efforts are original and novel research, as no such models had been developed prior to PEBBLES. They show that the the complex structure of dust grains, which shape and sizes evolve greatly during the disk assembly stages, needs to be taken into account when interpreting astronomical observations of the dense environments where stars and planets form.

Several observing programs to trace the thermal dust emission at submillimeter and milleter wavelengths have been carried out in 2024-2025, allowing to trace the evolution of dust properties from the dense ISM to the birthplaces of protoplanetary disks. They are either published, or about to be published. Following up on the early results, multi-wavelength observations are now being analyzed to constrin simultaneously the dust temperature and its emissivity, a key to lift degenracies.

A large program using the IRAM/NOEMA observatory has been kicked off, with first observations carried out in the Winter of 2024, allowing for the first time to probe the dust polarized emission at 3mm, at scales 100 au. While the scientific analysis is ongoing, it shows already several unexpected results, suggesting that further investigations about the early dust evolution and dust alignment mechanisms, must be carried out.

Fortschritte, die über den aktuellen Stand der Technik hinausgehen und voraussichtliche potenzielle Auswirkungen (einschließlich der bis dato erzielten sozioökonomischen Auswirkungen und weiter gefassten gesellschaftlichen Auswirkungen des Projekts)

The first results out of PEBBLES are extremely promising as they suggest that our vision of dust properties evolve significantly during the first stages of disk formation, and that detailed modeling of multi-wavelength astronomical datasets allows to put significant constraints on the dust sizes and composition. Such results are completely novel in their nature and methodology, promising to probe for the for the first time dust evolution not only in disk conditions but also in in protostellar environments. While the paradigm of the astronomical community studying planet-formation is currently shifting towards considering planetary bodies may be assembled much earlier than previously thought, the impact of PEBBLES could be transformational. The full fruition of this scientific exploration will only be attained when both millimeter and infrared observationsl datasets will be modeled with a unifying physically-motivated dust model: this is the goal of the PEBBLES team for the remaining of the project.