CAMPOS

II. The onset of protostellar disk substructures and planet formation

¹ Department of Astronomy, Yale University, New Haven, CT 06511, USA
² Department of Astronomy, The University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712-1205, USA
³ Max Planck Institute for Extraterrestrial Physics, Gießenbachstraße 1, 85748 Garching bei München, Germany
⁴ Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Chile
⁵ Department of Physics, Middlebury College, Middlebury, VT 05753, USA
⁶ Los Alamos National Laboratory, Santa Fe, NM 87545, USA
⁷ National Science Foundation-Simons AI Institute for Cosmic Origins, The University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712-1205, USA

^★ Corresponding author: chenghan.hsieh@utexas.edu

Received: 15 April 2025
Accepted: 24 June 2025

Abstract

The 1.3 mm CAMPOS survey has resolved 90 protostellar disks with ~15 au resolution across the Ophiuchus, Corona Australis, and Chamaeleon star-forming regions. To address the fundamental question of when planet formation begins, we combined the CAMPOS sample with literature observations of Class 0-II disks (bolometric temperature, T_bol ≤ 1900 K), all mapped at 1.3 mm with resolutions ranging from 4 to 33 au. To investigate substructure detection rates as a function of bolometric temperature, we restricted the sample to disks observed at a wavelength of 1.3 mm, with inclinations below 75° and linear resolutions ≤20 au, and resolved with at least four resolution elements (θ_disk/θ_res ≥ 4). We also considered the effects of extinction correction and the inclusion of Herschel Space Telescope data on the bolometric temperature measurements to constrain the lower and upper limits of bolometric temperature for each source. We find that by T_bol ~ 200-400 K, substructure detection rates increase sharply to ~60%, corresponding to an approximate age of 0.2–0.4 Myr. No substructures are detected in Class 0 disks. The ratio of disk-averaged brightness temperature to predicted dust temperature shows a trend of increasing values toward the youngest Class 0 disks, suggesting higher optical depths in these early stages. Our statistical analysis confirms that substructures similar to the ones in Class II disks are already common by the Class I stage, and the emergence of these structures at T_bol ~ 200-400 K could represent only an upper limit. Classifying disks with substructures into those with and without large central cavities, we find both populations coexisting across evolutionary stages, suggesting that they are not necessarily evolutionarily linked. Suppose protostellar disk substructures do follow an evolutionary sequence. In that case, our results imply that disk substructures evolve very rapidly and thus can be present in all Class I/II stages and/or that they can be triggered at different times.