February 19, 2026 | 11:00am - 12:00pm
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02/19/2026 11:00
02/19/2026 12:00
Institute for Advanced Study Astrophysics Seminar
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Topic: Rethinking about gravitational instability as a planet formation scenario
Speakers: Cristiano Longarini, University of Cambridge
More: https://www.ias.edu/sns/events/institute-advanced-study-astrophysics-seminar-141
The ubiquity of substructures in protoplanetary discs has opened
debate regarding the alignment of planet formation timescales with
protostellar disc evolution. Under the hypothesis of the planetary
interpretation, a robust conclusion is that a substantial part of the
planet formation process must overlap with the time when protostellar
discs are likely to be young and, possibly, gravitationally unstable.
Historically, gravitational instability has been proposed as a pathway
for planetary formation. However, it lost favour due to the higher
likelihood of forming stellar companions rather than planets.
Nevertheless, recently, this scenario has gained new interest, when
the synergy between gravitational instability and dust dynamics is
considered.
In this talk, I will discuss the interplay between dust dynamics and
gravitational instability. Gravitational instability is responsible
for the formation of a large scale spiral structure, that efficiently
traps dust. There, the dust concentration can be so high that it
becomes unstable, possibly collapsing into Earth-mass objects. We
analytically characterise this behaviour, and we confirm it through
numerical simulations, showing that planetary cores at large radii can
be efficiently formed in young protostellar discs.
Bloomberg Lecture Hall
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