SPIRAL WAVES TRIGGERED by SHADOWS in TRANSITION DISKS

Matías Montesinos, Sebastian Perez, Simon Casassus, Sebastian Marino, Jorge Cuadra, Valentin Christiaens

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45 Citations (Scopus)

Abstract

Circumstellar asymmetries such as central warps have recently been shown to cast shadows on outer disks. We investigate the hydrodynamical consequences of such variable illumination on the outer regions of a transition disk, and the development of spiral arms. Using 2D simulations, we follow the evolution of a gaseous disk passively heated by the central star, under the periodic forcing of shadows with an opening angle of ∼28°. With a lower pressure under the shadows, each crossing results in a variable azimuthal acceleration, which in time develops into spiral density waves. Their pitch angles evolve from Π ∼ 15°-22° at the onset, to ∼11°-14°, over ∼65 au to 150 au. Self-gravity enhances the density contrast of the spiral waves, as also reported previously for spirals launched by planets. Our control simulations with unshadowed irradiation do not develop structures, except for a different form of spiral waves seen at later times only in the gravitationally unstable control case. Scattered light predictions in the H-band show that such illumination spirals should be observable. We suggest that spiral arms in the case-study transition disk HD 142527 could be explained as a result of shadowing from the tilted inner disk.

Original languageEnglish
Article numberL8
Number of pages6
JournalThe Astrophysical Journal Letters
Volume823
Issue number1
DOIs
Publication statusPublished - 20 May 2016
Externally publishedYes

Keywords

  • accretion, accretion disks
  • hydrodynamics
  • methods: numerical
  • planets and satellites: dynamical evolution and stability
  • protoplanetary disks

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