Three Radial Gaps in the Disk of TW Hydrae Imaged with SPHERE
Résumé
We present scattered light images of the TW Hya disk performed with the Spectro‐Polarimetric High‐contrast Exoplanet REsearch instrument in Polarimetric Differential Imaging mode at 0.63, 0.79, 1.24, and 1.62 mu m. We also present H2/H3‐band angular differential imaging (ADI) observations. Three distinct radial depressions in the polarized intensity distribution are seen, around approximate to 85, approximate to 21, and less than or similar to 6 au.(21) The overall intensity distribution has a high degree of azimuthal symmetry; the disk is somewhat brighter than average toward the south and darker toward the north‐west. The ADI observations yielded no signifiant detection of point sources in the disk. Our observations have a linear spatial resolution of 1‐2 au, similar to that of recent ALMA dust continuum observations. The submicron‐ sized dust grains that dominate the light scattering in the disk surface are strongly coupled to the gas. We created a radiative transfer disk model with self‐consistent temperature and vertical structure iteration and including grain size‐dependent dust settling. This method may provide independent constraints on the gas distribution at higher spatial resolution than is feasible with ALMA gas line observations. We find that the gas surface density in the ``gaps'' is reduced by approximate to 50% to approximate to 80% relative to an unperturbed model. Should embedded planets be responsible for carving the gaps then their masses are at most a few 10M(circle plus). The observed gaps are wider, with shallower flanks, than expected for planet‐disk interaction with such low‐mass planets. If forming planetary bodies have undergone collapse and are in the ``detached phase,'' then they may be directly observable with future facilities such as the Mid‐Infrared E‐ELT Imager and Spectrograph at the E‐ELT.
Domaines
Astrophysique [astro-ph]| Origine | Fichiers produits par l'(les) auteur(s) |
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