The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. V. A Characterization of Protostellar Multiplicity

John J. Tobin, Stella S.R. Offner, Kaitlin M. Kratter, S. Thomas Megeath, Patrick D. Sheehan, Leslie W. Looney, Ana Karla Diaz-Rodriguez, Mayra Osorio, Guillem Anglada, Sarah I. Sadavoy, Elise Furlan, Dominique Segura-Cox, Nicole Karnath, Merel L.R. Van 'T Hoff, Ewine F. Van Dishoeck, Zhi Yun Li, Rajeeb Sharma, Amelia M. Stutz, Łukasz Tychoniec

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


We characterize protostellar multiplicity in 20 Current address: Niels Bohr Institute, University of Copenhagen, Øster Voldgade 5a7, DK-1350, Copenhagen K, Denmark. the Orion molecular clouds using Atacama Large Millimeter/submillimeter Array 0.87 mm and Very Large Array 9 mm continuum surveys toward 328 protostars. These observations are sensitive to projected spatial separations as small as ∼20 au, and we consider source separations up to 104 au as potential companions. The overall multiplicity fraction (MF) and companion fraction (CF) for the Orion protostars are 0.30 ± 0.03 and 0.44 ± 0.03, respectively, considering separations from 20 to 104 au. The MFs and CFs are corrected for potential contamination by unassociated young stars using a probabilistic scheme based on the surface density of young stars around each protostar. The companion separation distribution as a whole is double peaked and inconsistent with the separation distribution of solar-type field stars, while the separation distribution of Flat Spectrum protostars is consistent solar-type field stars. The multiplicity statistics and companion separation distributions of the Perseus star-forming region are consistent with those of Orion. Based on the observed peaks in the Class 0 separations at ∼100 au and ∼103 au, we argue that multiples with separations <500 au are likely produced by both disk fragmentation and turbulent fragmentation with migration, and those at ?3103 au result primarily from turbulent fragmentation. We also find that MFs/CFs may rise from Class 0 to Flat Spectrum protostars between 100 and 103 au in regions of high young stellar object density. This finding may be evidence for the migration of companions from >103 au to <103 au, and that some companions between 103 and 104 au must be (or become) unbound.

Original languageEnglish (US)
Article number39
JournalAstrophysical Journal
Issue number1
StatePublished - Jan 1 2022

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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