TW Hya: An old protoplanetary disc revived by its planet

Sergei Nayakshin, Takashi Tsukagoshi, Cassandra Hall, Allona Vazan, Ravit Helled, Jack Humphries, Farzana Meru, Patrick Neunteufel, Olja Panic

Research output: Contribution to journalArticlepeer-review


Dark rings with bright rims are the indirect signposts of planets embedded in protoplanetary discs. In a recent first, an azimuthally elongated AU-scale blob, possibly a planet, was resolved with ALMA in TW Hya. The blob is at the edge of a cliff-like rollover in the dust disc rather than inside a dark ring. Here we build time-dependent models of TW Hya disc. We find that the classical paradigm cannot account for the morphology of the disc and the blob. We propose that ALMA-discovered blob hides a Neptune mass planet losing gas and dust. We show that radial drift of mm-sized dust particles naturally explains why the blob is located on the edge of the dust disc. Dust particles leaving the planet perform a characteristic U-turn relative to it, producing an azimuthally elongated blob-like emission feature. This scenario also explains why a 10 Myr old disc is so bright in dust continuum. Two scenarios for the dust-losing planet are presented. In the first, a dusty pre-runaway gas envelope of a ∼ 40 M Core Accretion planet is disrupted, e.g. as a result of a catastrophic encounter. In the second, a massive dusty pre-collapse gas giant planet formed by Gravitational Instability is disrupted by the energy released in its massive core. Future modelling may discriminate between these scenarios and allow us to study planet formation in an entirely new way – by analysing the flows of dust and gas recently belonging to planets, informing us about the structure of pre-disruption planetary envelopes.

Original languageEnglish
Pages (from-to)285-304
Number of pages20
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - 1 Jun 2020
Externally publishedYes

Bibliographical note

Funding Information:
The authors thank John Ilee for useful discussions and suggestions. SN acknowledges support from STFC grants ST/N000757/1 and ST/M006948/1 to the University of Leicester. This work made use of the DiRAC Data Intensive service at Leicester, operated by the University of Leicester IT Services, which forms part of the STFC DiRAC HPC Facility ( The equipment was funded by BEIS capital funding via STFC capital grants ST/K000373/1 and ST/R002363/1 and STFC DiRAC Operations grant ST/R001014/1. DiRAC is part of the National e-Infrastructure. CH is a Winton Fellow and this work has been supported by Winton Philanthropies, The David and Claudia Harding Foundation. FM acknowledges support from the Royal Society Dorothy Hodgkin Fellowship.

Publisher Copyright:
© 2020 The Author(s).


  • Planets and satellites: Formation
  • Protoplanetary discs


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