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Published June 10, 2025 | Version Published
Journal Article Open

The SOFIA Massive (SOMA) Star Formation Survey. V. Clustered Protostars

Creators

  • 1. ROR icon University of Virginia
  • 2. ROR icon Instituto de Astrofísica de Andalucía
  • 3. ROR icon Chalmers University of Technology
  • 4. ROR icon Arcetri Astrophysical Observatory
  • 5. ROR icon Shanghai Jiao Tong University
  • 6. ROR icon National Radio Astronomy Observatory
  • 7. ROR icon RIKEN
  • 8. ROR icon Search for Extraterrestrial Intelligence
  • 9. ROR icon European Southern Observatory
  • 10. Rosseland Centre for Solar Physics, Institute of Theoretical Astrophysics, Sem Salands vei 13, 0371 Oslo, Norway
  • 11. ROR icon California Institute of Technology
  • 12. ROR icon National Astronomical Observatory of Japan
  • 13. Institute of Science Tokyo
  • 14. ROR icon University of Cologne

Abstract

We present ∼8–40 μm SOFIA-FORCAST images of seven regions of "clustered" star formation as part of the SOFIA Massive Star Formation Survey. We identify a total of 34 protostar candidates and build their spectral energy distributions (SEDs). We fit these SEDs with a grid of radiative transfer models based on the turbulent core accretion (TCA) theory to derive key protostellar properties, including initial core mass, Mc, clump environment mass surface density, Σcl, and current protostellar mass, m*. We also carry out empirical graybody (GB) estimation of Σcl, which allows a case of restricted SED fitting within the TCA model grid. We also release version 2.0 of the open-source Python package sedcreator, which is designed to automate the aperture photometry and SED building and fitting process for sources in clustered environments, where flux contamination from close neighbors typically complicates the process. Using these updated methods, SED fitting yields values of Mc ∼ 30–200 M⊙, Σcl,SED ∼ 0.1–3 g cm−2, and m* ∼ 4–50 M⊙. The GB fitting yields smaller values of Σcl,GB ≲ 1 g cm−2. From these results, we do not find evidence for a critical Σcl needed to form massive (≳8 M⊙) stars. However, we do find tentative evidence for a dearth of the most massive (m* ≳ 30 M⊙) protostars in the clustered regions, suggesting a potential impact of environment on the stellar initial mass function.

Copyright and License

© 2025. The Author(s). Published by the American Astronomical Society.

Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

R.F. acknowledges support from the grants Juan de la Cierva FJC2021-046802-I, PID2020-114461GB-I00, and PID2023-146295NB-I00, and from the Severo Ochoa grant CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033 and by "European Union NextGenerationEU/PRTR". J.C.T. acknowledges support from USRA-SOFIA grant 09_0085, NSF grants AST-2009674 and AST-2206450, ERC Advanced grant 788829 (MSTAR), and the CCA Sabbatical Visiting Researcher program. G.C. acknowledges support from the ESO Fellowship Program and funding from the Swedish Research Council (VR grant; Project: 2021-05589).

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Additional details

Related works

Is new version of
Discussion Paper: arXiv:2412.11792 (arXiv)

Funding

Ministerio de Ciencia e Innovación
FJC2021-046802-I
Ministerio de Ciencia e Innovación
PID2020-114461GB-I00
Ministerio de Ciencia e Innovación
PID2023-146295NB-I00
Fundación Carmen y Severo Ochoa
10.13039/501100011033
Universities Space Research Association
09_0085
National Science Foundation
AST-2009674
National Science Foundation
AST-2206450
European Research Council
788829
Simons Foundation
Center for Computational Astrophysics -
European Southern Observatory
Vetenskapsrådet
2021-05589

Dates

Accepted
2025-02-21
Available
2025-06-03
Published

Caltech Custom Metadata

Caltech groups
Division of Physics, Mathematics and Astronomy (PMA)
Publication Status
Published