Multiple (forming) planets at Sz 91?

Subject: Multiple (forming) planets at Sz 91? 18th March 2015, 5:00 am

Quote :: We present ALMA (Cycle 0) band-6 and band-3 observations of the transition disk Sz 91. The disk inclination and position angle are determined to be i = 49.5◦ ±3.5 and PA = 18.2±3.5◦ andthe dusty and gaseous disk are detected up to ∼220 au and ∼ 400 au from the star, respectively. Most importantly, our continuum observations indicate that the cavity size in the mm-sized dust distribution must be ∼ 97 au in radius, the largest cavity observed around a T Tauri star. Our data clearly confirms the presence of 12CO (2-1) well inside the dust cavity. Based on these observational constrains we developed a disk model that simultaneously accounts for the 12CO and continuum observations (i.e., gaseous and dusty disk). According to our model, most of themillimeter emission comes from a ring located between 97 and 140 au. We also find that the dust cavity is divided into an innermost region largely depleted of dust particles ranging from the dust sublimation radius up to 85 au, and a second, moderately dust-depleted region, extendingfrom 85 to 97 au. The extremely large size of the dust cavity, the presence of gas and small dust particles within the cavity and the accretion rate of Sz 91 are consistent with the formation of multiple (giant) planets.