FAUST

Astronomy and Astrophysics, vol. 711, pp. A117

Abstract

Aims . To advance our understanding of dust properties in class 0/I young stellar objects, it is essential to resolve and characterize their structures at multiple wavelengths and investigate how both grain growth and environmental factors shape their spectral properties. Methods . We present 0.″5 angular resolution ALMA observations of the GSS 30 complex at 1.2–3.0 mm, collected as part of the FAUST large programme, with a linear resolution of 69 au. We analysed the dust continuum emission and performed model fitting to constrain the dust mass and the disk structure. Results . For IRS3, the spectral index increases radially from 2.0 at the centre to 2.5 at the disk edge. In contrast, it decreases from 2.0 to as low as 1.6–1.8 along the outflow direction. An asymmetric distribution shows α as low as 1.6 to the northeastern blueshifted lobe, possibly due to cold outer envelope dust obscuring warmer inner regions. Spectral energy distribution fitting indicates maximum dust grain sizes of tens of microns and a dust mass of 650–1510 M ⊕ . IRS1 is connected with an extended structure to the north-east. It may be an outflow–disk complex or a trailing structure associated with a circumbinary disk, although we cannot rule out the possibility that it could also be a gas streamer accreting onto IRS1. At the centre of IRS1, the spectral index is < 0.8, which is consistent with marginally optically thick free-free emission. IRS2 exhibits brightness variations over 420 seconds of observation, with a multi-epoch comparison suggesting a flare lasting tens of minutes, indicating magnetic activity in the central star. Conclusions . This study presents a detailed millimetre multi-wavelength analysis of the GSS 30 IRS3 and IRS1 systems, highlighting the crucial role of environmental factors – specifically dust obscuration and the connecting streamer structures – in shaping the observed morphology of these early-stage disks. We also find that the IRS2 exhibits millimetre variability, which may originate from magnetic flares at the surface of the protostar.

Authors 58

1. Qiancheng Yang

   Xiamen University

   Affiliation as printed

   Department of Astronomy, Xiamen University

2. Hauyu Baobab Liu

   National Taiwan Normal University · National Sun Yat-sen University

   Affiliation as printed

   Center of Astronomy and Gravitation, National Taiwan Normal University

   Department of Physics, National Sun Yat-Sen University

3. Siyi Feng

   Xiamen University

   Affiliation as printed

   Department of Astronomy, Xiamen University

4. C. J. Chandler

   National Radio Astronomy Observatory

   Affiliation as printed

   National Radio Astronomy Observatory

5. F. Fontani

   Centre National de la Recherche Scientifique · Université Paris Sciences et Lettres · Arcetri Astrophysical Observatory · Observatoire de Paris · Max Planck Institute for Extraterrestrial Physics · Laboratoire d'Étude de l'Univers et des Phénomènes Extrêmes · National Institute for Astrophysics

   Affiliation as printed

   Istituto Nazionale di Astrofisica (INAF), Osservatorio Astrofisico di Arcetri

   LUX, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités

   Max-Planck-Institut für extraterrestrische Physik (MPE)

6. Nami Sakai

   RIKEN

   Affiliation as printed

   RIKEN Cluster for Pioneering Research

7. Yoko Oya

   Kyoto University · Yukawa Institute for Theoretical Physics

   Affiliation as printed

   Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto University

8. T. Hanawa

   Chiba University

   Affiliation as printed

   Center for Frontier Science, Chiba University

9. C. Codella

   Centre National de la Recherche Scientifique · Arcetri Astrophysical Observatory · Institut de Planétologie et d'Astrophysique de Grenoble · National Institute for Astrophysics · Université Grenoble Alpes

   Affiliation as printed

   Istituto Nazionale di Astrofisica (INAF), Osservatorio Astrofisico di Arcetri

   Univ. Grenoble Alpes, CNRS, IPAG

10. Cecilia Ceccarelli

    Centre National de la Recherche Scientifique · Institut de Planétologie et d'Astrophysique de Grenoble · Université Grenoble Alpes

    Affiliation as printed

    Univ. Grenoble Alpes, CNRS, IPAG

11. Izaskun Jiménez-Serra

    Centro de Astrobiología

    Affiliation as printed

    Centro de Astrobiología (CAB), INTA-CSIC

12. Luca Cacciapuoti

    European Southern Observatory · European Southern Observatory

    Affiliation as printed

    European Southern Observatory

13. E. Bianchi

    Arcetri Astrophysical Observatory · National Institute for Astrophysics

    Affiliation as printed

    Istituto Nazionale di Astrofisica (INAF), Osservatorio Astrofisico di Arcetri

14. Mathilde Bouvier Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory, Leiden University

15. M. De Simone

    European Southern Observatory · Arcetri Astrophysical Observatory · European Southern Observatory · National Institute for Astrophysics

    Affiliation as printed

    European Southern Observatory

    Istituto Nazionale di Astrofisica (INAF), Osservatorio Astrofisico di Arcetri

16. A. Isella

    Rice University

    Affiliation as printed

    Department of Physics and Astronomy, Rice University

17. D Johnstone

    Herzberg Institute of Astrophysics · University of Victoria

    Affiliation as printed

    Department of Physics and Astronomy, University of Victoria

    NRC Herzberg Astronomy and Astrophysics

18. L. Loinard

    Harvard University · Universidad Nacional Autónoma de México

    Affiliation as printed

    Black Hole Initiative at Harvard University

    David Rockefeller Center for Latin American Studies, Harvard University

    Instituto de Radioastronomía y Astrofísica , Universidad Nacional Autónoma de México

19. G. Sabatini

    Arcetri Astrophysical Observatory · National Institute for Astrophysics

    Affiliation as printed

    Istituto Nazionale di Astrofisica (INAF), Osservatorio Astrofisico di Arcetri

20. Yancy L. Shirley
    Affiliation as printed

    Steward Observatory

21. Y. Aikawa

    The University of Tokyo

    Affiliation as printed

    Department of Astronomy, The University of Tokyo

22. María José Maureira

    Max Planck Society · Max Planck Institute for Extraterrestrial Physics

    Affiliation as printed

    Center for Astrochemical Studies, Max-Planck-Institut für extrater-restrische Physik (MPE)

23. P. Caselli

    Max Planck Society · Max Planck Institute for Extraterrestrial Physics

    Affiliation as printed

    Center for Astrochemical Studies, Max-Planck-Institut für extrater-restrische Physik (MPE)

24. F. Ménard

    Centre National de la Recherche Scientifique · Institut de Planétologie et d'Astrophysique de Grenoble · Université Grenoble Alpes

    Affiliation as printed

    Univ. Grenoble Alpes, CNRS, IPAG

25. N. Balucani

    University of Perugia

    Affiliation as printed

    Department of Chemistry, Biology, and Biotechnology, The University of Perugia

26. E. Caux

    Centre National de la Recherche Scientifique · Université Toulouse III - Paul Sabatier · Institut de Recherche en Astrophysique et Planétologie · Université de Toulouse

    Affiliation as printed

    IRAP, Univ. de Toulouse, CNRS, CNES, UPS

27. S. B. Charnley
    Affiliation as printed

    Astrochemistry Laboratory

28. Nicolás Cuello

    Centre National de la Recherche Scientifique · Institut de Planétologie et d'Astrophysique de Grenoble · Université Grenoble Alpes

    Affiliation as printed

    Univ. Grenoble Alpes, CNRS, IPAG

29. F. Dulieu

    Centre National de la Recherche Scientifique · Université Paris Sciences et Lettres · Observatoire de Paris · Sorbonne Université · Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères · CY Cergy Paris Université

    Affiliation as printed

    CY Cergy Paris Université, Sorbonne Université, Observatoire de Paris, PSL University, CNRS, LERMA

30. L. Evans

    University of Leeds

    Affiliation as printed

    School of Physics and Astronomy, University of Leeds

31. D. Fedele

    Arcetri Astrophysical Observatory · National Institute for Astrophysics

    Affiliation as printed

    Istituto Nazionale di Astrofisica (INAF), Osservatorio Astrofisico di Arcetri

32. T. Hama

    The University of Tokyo

    Affiliation as printed

    Department of Basic Science, The University of Tokyo

    Komaba Institute for Science, The University of Tokyo

33. Eric Herbst

    University of Virginia

    Affiliation as printed

    Department of Chemistry, University of Virginia

34. T. Hirota

    The Graduate University for Advanced Studies, SOKENDAI · National Astronomical Observatory of Japan

    Affiliation as printed

    National Astronomical Observatory of Japan

    SOKENDAI (The Graduate University for Advanced Studies)

35. Bertrand Lefloch

    Centre National de la Recherche Scientifique · Université de Bordeaux · Laboratoire d'Astrophysique de Bordeaux

    Affiliation as printed

    Université de Bordeaux – CNRS Laboratoire d’Astrophysique de Bordeaux

36. A. Lopez-Sepulcre

    Centre National de la Recherche Scientifique · Institut de Radioastronomie Millimétrique · Institut de Planétologie et d'Astrophysique de Grenoble · Université Grenoble Alpes

    Affiliation as printed

    Institut de Radioastronomie Millimétrique

    Univ. Grenoble Alpes, CNRS, IPAG

37. Luke T. Maud

    European Southern Observatory · European Southern Observatory

    Affiliation as printed

    European Southern Observatory

38. Anna Miotello

    European Southern Observatory · European Southern Observatory

    Affiliation as printed

    European Southern Observatory

39. G. Moellenbrock

    National Radio Astronomy Observatory

    Affiliation as printed

    National Radio Astronomy Observatory

40. H. Nomura

    The Graduate University for Advanced Studies, SOKENDAI · National Astronomical Observatory of Japan

    Affiliation as printed

    National Astronomical Observatory of Japan

    SOKENDAI (The Graduate University for Advanced Studies)

41. Y. Oba

    Hokkaido University

    Affiliation as printed

    Institute of Low Temperature Science, Hokkaido University

42. S. Ohashi

    RIKEN · National Astronomical Observatory of Japan

    Affiliation as printed

    National Astronomical Observatory of Japan

    RIKEN Cluster for Pioneering Research

43. Y. Okoda

    Herzberg Institute of Astrophysics · RIKEN

    Affiliation as printed

    NRC Herzberg Astronomy and Astrophysics

    RIKEN Cluster for Pioneering Research

44. J. Sebastian Pineda

    Max Planck Society · Max Planck Institute for Extraterrestrial Physics

    Affiliation as printed

    Center for Astrochemical Studies, Max-Planck-Institut für extrater-restrische Physik (MPE)

45. L. Podio

    Arcetri Astrophysical Observatory · National Institute for Astrophysics

    Affiliation as printed

    Istituto Nazionale di Astrofisica (INAF), Osservatorio Astrofisico di Arcetri

46. A. Rimola

    Universitat Autònoma de Barcelona

    Affiliation as printed

    Departament de Química, Universitat Autònoma de Barcelona

47. T. Sakai

    University of Electro-Communications

    Affiliation as printed

    Graduate School of Informatics and Engineering, The University of Electro-Communications

48. D. M. Segura-Cox

    The University of Texas at Austin

    Affiliation as printed

    Department of Astronomy, The University of Texas at Austin

49. Brian Svoboda

    National Radio Astronomy Observatory

    Affiliation as printed

    National Radio Astronomy Observatory

50. L. Testi

    Arcetri Astrophysical Observatory · National Institute for Astrophysics · University of Bologna

    Affiliation as printed

    Alma Mater Studiorum – Università di Bologna, Dipartimento di Fisica e Astronomia “Augusto Righi”

    Istituto Nazionale di Astrofisica (INAF), Osservatorio Astrofisico di Arcetri

51. C. Vastel

    Centre National de la Recherche Scientifique · Université Toulouse III - Paul Sabatier · Institut de Recherche en Astrophysique et Planétologie · Université de Toulouse

    Affiliation as printed

    IRAP, Univ. de Toulouse, CNRS, CNES, UPS

52. S. Viti Aachen Leiden Observatory

    Leiden University · University of Bonn · Leiden Observatory

    Affiliation as printed

    Leiden Observatory, Leiden University

    Transdisciplinary Research Area (TRA) ‘Matter’/Argelander-Institut für Astronomie, University of Bonn

53. N. Watanabe

    Universitat Autònoma de Barcelona

    Affiliation as printed

    Departament de Química, Universitat Autònoma de Barcelona

54. Y. Watanabe

    Shibaura Institute of Technology

    Affiliation as printed

    Materials Science and Engineering, College of Engineering, Shibaura Institute of Technology

55. Y. Zhang

    Shanghai Jiao Tong University

    Affiliation as printed

    Department of Astronomy, Shanghai Jiao Tong University

56. Z.-E. Zhang

    RIKEN

    Affiliation as printed

    Star and Planet Formation Laboratory, RIKEN Cluster for Pioneering Research

57. F. O. Alves

    Institut de Radioastronomie Millimétrique

    Affiliation as printed

    Institut de Radioastronomie Millimétrique

58. S. Yamamoto

    The Graduate University for Advanced Studies, SOKENDAI

    Affiliation as printed

    SOKENDAI (The Graduate University for Advanced Studies)