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~$M_{\text{sun}}$ T Tauri star CIDA 1 using the Karl G. Jansky Very Large Array (JVLA) at multiple centimeter wavelengths, with a spatial resolution of 0${}^{\mathrm{\prime }\mathrm{\prime }}$2–0${}^{\mathrm{\prime }\mathrm{\prime }}$9. We detected distinct partial-ring structures at these wavelengths around CIDA~1. Based on spatial distributions and spectral indexes, we determined that these centimeter emissions originated from dust, rather than free-free or synchrotron emissions. To estimate the maximum grain size ($a_{\mathrm{m}\mathrm{a}\mathrm{x}}$) within the ring, we compared the observed spectral energy distribution (SED) with SEDs calculated for different $a_{\mathrm{m}\mathrm{a}\mathrm{x}}$ values using radiative transfer calculations. Our findings indicate an $a_{\mathrm{m}\mathrm{a}\mathrm{x}}$ value of approximately 2.5~cm in the ring, assuming 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.