The Characterization of the Dust Content in the Ring Around Sz 91: Indications of Planetesimal Formation?

Karina Maucó, Carlos Carrasco-González, Matthias R. Schreiber, Anibal Sierra, Johan Olofsson, Amelia Bayo, Claudio Caceres, Hector Canovas, Aina Palau

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


One of the most important questions in the field of planet formation is how millimeter- and centimeter-sized dust particles overcome radial drift and fragmentation barriers to form kilometer-sized planetesimals. ALMA observations of protoplanetary disks, in particular transition disks or disks with clear signs of substructures, can provide new constraints on theories of grain growth and planetesimal formation, and therefore represent one possibility for progress on this issue. We here present ALMA band 4 (2.1 mm) observations of the transition disk system Sz 91, and combine them with previously obtained band 6 (1.3 mm) and band 7 (0.9 mm) observations. Sz 91, with its well-defined millimeter ring, more extended gas disk, and evidence of smaller dust particles close to the star, constitutes a clear case of dust filtering and the accumulation of millimeter-sized particles in a gas pressure bump. We compute the spectral index (nearly constant at ~3.34), optical depth (marginally optically thick), and maximum grain size (~0.61 mm) in the dust ring from the multi-wavelength ALMA observations, and compare the results with recently published simulations of grain growth in disk substructures. Our observational results are in strong agreement with the predictions of models for grain growth in dust rings that include fragmentation and planetesimal formation through streaming instability.

Original languageEnglish
Article number128
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 10 Dec 2021

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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