2017/11/09 by Attila Juhasz, Á. Juhász, Giovanni P. Rosotti +1
Chemistry · Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Molecular Spectroscopy and Structure #Optics #Physics #Planet #Radiative transfer #Spiral (railway) #Spiral galaxy #Stars #Stellar, planetary, and galactic studies #Stratification (seeds) #Thermal #astro-ph.EP
paper · pdf · doi:10.1093/mnrasl/slx182
5 pages, 4 figures, accepted for publication in MNRAS
arxiv created 2017/11/09 · openalex publication_date 2017/11/13 · arxiv updated 2017/12/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract Spiral arms have been observed in nearly a dozen protoplanetary discs in near-infrared scattered light and recently also in the submillimetre continuum. While one of the most compelling explanations is that they are driven by planetary or stellar companions, in all but one cases such companions have not yet been detected and there is even ambiguity on whether the planet should be located inside or outside the spirals. Here, we use 3D hydrodynamic simulations to study the morphology of spiral density waves launched by embedded planets taking into account the vertical temperature gradient, a natural consequence of stellar irradiation. Our simulations show that the pitch angle of the spirals in thermally stratified discs is the lowest in the disc mid-plane and increases towards the disc surface. We combine the hydrodynamic simulations with 3D radiative transfer calculations to predict that the pitch angle of planetary spirals observed in the near-infrared is higher than in the submillimetre. We also find that in both cases the spirals converge towards the planet. This provides a new powerful observational method to determine if the perturbing planet is inside or outside the spirals, as well as map the thermal stratification of the disc.