Horizon Europe -
ERC Consolidator Grant
"Early phases of planetary birth sites:
environmental context and
interstellar inheritance"
The aim of this ambitious research project is to produce the most realistic computer simulations of the assembly of gaseous protoplanetary accretion discs, and to under- stand which of their traits are inherited from and / or affected by their direct interstellar context.
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Project overview
Planet formation is not merely ubiquitous, but figuratively speaking happens within the blink of an eye. Surveys such as D-SHARP (using the ALMA telescope array) show growing evidence for feature-rich young disks. This implies that we should shift our focus towards early stages of circum-stellar discs, that is, systems at the point of transition from Class I to Class II, which moreover mandates to abandon the assumption of the disk as a quiescent entity detached from its surroundings.
At the earliest stages, we really should include the wider context of the systems, such as for instance their protostellar envelopes. Moreover, environmental context becomes key. Actively star-forming stellar associations can disrupt and affect the very processes were are interested in.
The bottom line is that we need to significant expand our previous models in terms of physical realism. Most prominently, we now include the gas self-gravity, and study how this alters the role played by magnetic fields.
Highlight: Exact self-gravity kernel for 2D
Direct gravitational instability is one of the two central theories trying to explain the formation of gas giant planets. Provided that cooling is sufficiently fast, it describes how an initially massive gaseous disk can fragment into clumps. A fundamental challenge of the theory is that the resulting clumps tend to be too massive — that is, more akin to a Brown dwarf than a Jupiter-mass planet.
Simplified “2D flat” simulations of protoplanetary disks that incorporate self-gravity must introduce a softening prescription of the gravitational potential to account for the vertical distribution of the gas. Our previous work showed that this prescription underestimates the short- and intermediate-range interaction of self-gravitating gas by up to 100% — thereby inhibiting gravitational collapse and specifically fragmentation. Consequently, the initial mass of objects formed through this channel could be overestimated, since the gravitational potential behaves as if it were shielded.
Gravitational collapse inside a vortex: The figure illustrates the dust accumulation in a two-dimensional simulation of a gravitationally unstable gas vortex. Using the novel kernel, gravitational collapse of dust, followed by a gas envelope capture, inside a vortex becomes possible.
In our research, we focus on an analytical model for computing faithfully and accurately (i.e., up to 0.3%) self-gravity in 2D simulations. Employing a direct vertical integration of the 3D forces permits to compute a 2D kernel that goes beyond the oversimplified “Plummer” potential and, moreover, is adaptive to local conditions.
related publications
- “Self-gravity in thin-disc simulations of protoplanetary discs: The smoothing length rectified and generalised to bi-fluids”
Rendon Restrepo, S., Barge, P. (2023), A&A 675, A96
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This work was co-funded by the European Union |
Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them.