From Disks to Comets: A Multi-frequency Study of Dust from Ophiuchus Molecular Cloud to the Oort Cloud

Planet formation, both in our Solar System and in extrasolar systems, is strongly influenced by the initial conditions of protoplanetary disks (PPDs)—including their mass, size, surface density, and temperature profile. Their subsequent evolution is governed by processes such as radial drift, vertical mixing, and grain growth. A major challenge in this context is understanding how dust grains grow into millimeter- to centimeter-sized particles. Such large grains, found in comets, serve as local analogs to solids in young disks and offer insights into early grain growth. Yet, such particles, which also dominate the total coma mass, remain largely unexplored. Large particles also contribute to the grain size distribution, a key factor in estimating dust mass in PPDs. Accurate dust mass estimates are essential to evaluate the potential to form planetesimals, rocky planets, and giant planet cores, but current estimates are highly uncertain and insufficient to explain the observed high incidence of massive exoplanets. These challenges—uncertainties in PPD dust masses and limited characterization of large particles—can be addressed through multi-frequency analysis of dust in both PPDs and comets. I will present the statistical results on dust surface density, maximum grain size, and temperature profiles for PPDs in the Ophiuchus molecular cloud observed with ALMA, emphasizing differences between single- and multi-frequency dust mass estimates. In parallel, I will present ALMA dust continuum observations of two long-period comets, C/2023 A3 (2024.1.01166.S, PI: Chavan, P) and C/2017 K2, alongside key results of their composition from mid-infrared spectroscopy with VLT/VISIR (113.26LA, PI: Chavan, P).