Hayashi-et-al-2

Images of disks around 19 protostars, including 4 binary systems observed with the ALMA. For 1 binary system, disks around the primary and secondary are presented independently (2nd line rightmost and 3rd line leftmost). Disks are presented in the order of their evolutionary sequence (the one in the upper-left corner is the youngest while the one at the lower-right corner is the oldest). The two oldest disks show faint ring-gap structures. A scale bar of 20 au (1 au corresponds to the distance between the Earth and the Sun, which is 150 million kilometer) is shown for each disk image. Credit: ALMA (ESO/NAOJ/NRAO), N. Ohashi et al.