Centimeter-sized Grains in the Compact Dust Ring around Very-low-mass Star CIDA 1

We examined the grain size in the dust ring encircling the 0.19 M☉ T Tauri star CIDA 1 using the Karl G. Jansky Very Large Array at multiple centimeter wavelengths, with a spatial resolution of 0farcs2–0farcs9. We detected distinct partial-ring structures at these wavelengths around CIDA 1. Based on spatial distributions and spectral indices, we determined that these centimeter emissions originated from dust, rather than free–free or synchrotron emissions. To estimate the maximum grain size (${a}_{\max }$) within the ring, we compared the observed spectral energy distribution (SED) with SEDs calculated for different ${a}_{\max }$ values using radiative transfer calculations. Our findings indicate an ${a}_{\max }$ value of approximately 2.5 cm in the ring, assuming that the dust opacity can be approximated by the DSHARP models. These results suggest that grain growth took place within the CIDA 1 ring, potentially facilitating more efficient planet formation through pebble accretion scenarios involving centimeter-sized pebbles.