2016/05/01 by Takashi Tsukagoshi, Hideko Nomura, Takayuki Muto +7 · 1 voice
Physics and Astronomy · #astro-ph.SR
paper · pdf · doi:10.3847/2041-8205/829/2/l35
arxiv published 2016/05/01 · arxiv created 2016/09/01 · arxiv updated 2016/09/01
We report ∼3 au resolution imaging observations of the protoplanetary disk around TW Hya at 145 and 233 GHz with the Atacama Large Millimeter/Submillimeter Array. Our observations revealed two deep gaps (∼25--50 %) at 22 and 37~au and shallower gaps (a few %) at 6, 28, and 44~au, as recently reported by Andrews et al. (2016). The central hole with a radius of ∼3~au was also marginally resolved. The most remarkable finding is that the spectral index α(R) between bands 4 and 6 peaks at the 22~au gap. The derived power-law index of the dust opacity β(R) is ∼1.7 at the 22~au gap and decreases toward the disk center to ∼0. The most prominent gap at 22~au could be caused by the gravitational interaction between the disk and an unseen planet with a mass of \lesssim1.5 MNeptune although other origins may be possible. The planet-induced gap is supported by the fact that β(R) is enhanced at the 22~au gap, indicating a deficit of ∼mm-sized grains within the gap due to dust filtration by a planet.