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6th of October 2016
Cavities, gaps and rings: signposts to planets
by Sarah Maddison (Swinburne University)
Cavities, gaps and rings in dusty disks around young stars are signposts of planets. We used both the ATCA and the ALMA radio telescopes to image the disk around the young star HD 97048. The top row shows the ALMA 0.85 mm (left panel) and 2.8 mm (central panel) and the ATCA 8.8 mm (right panel) observations. The bottom row shows three different image reconstructions of the ALMA 0.85 mm observation, which enhance the resolution to show the detail of the structure in the dusty disk around this young star. We find an inner cavity in the ALMA 0.85 mm image that extends to about 45 au (which is just over the distance Pluto is from our Sun) and also find a gap/ring in the outer disk. The cavity is not seen in the ATCA image because the young star emits radiation at these longer wavelengths. The beam shown in orange in the bottom left of each panel is the effective resolution of each image. Simple modelling of the multi-wavelength dataset suggests that a planet 0.7 times the mass of Jupiter could gravitationally clear the inner cavity seen in the 0.85 mm image. Detailed structures in transition disks like that seen in HD 97048 are likely common and ALMA now allows us to view these structures in detail. The combination of ALMA observations with the long wavelengths offered by ATCA allows us to fully understand the physics of these star+disk+planet systems. Image adapted from van der Plas et al. (2016).

Reference: Gerrit van der Plas, Chris Wright, Francois Menard, Simon Casassus, Canovas, Christophe Pinte, Sarah Maddison, Koen Maaskant, Henning Avenhaus, Lucas Cieza, Laura Perez and Catarina Ubach, 2016, Astronomy & Astrophysics, in press (Astro-ph/1609-02488)

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