FAUST

Springer Link (Chiba Institute of Technology)

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 56

1. Qiancheng Yang

   Xiamen University

   Affiliation as printed

   Department of Astronomy , Xiamen University , Zengcuoan West Road , Xiamen , 361005

2. Hauyu Baobab Liu

   National Taiwan Normal University · National Sun Yat-sen University

   Affiliation as printed

   Center of Astronomy and Gravitation , National Taiwan Normal Uni- versity , Taipei 116

   Department of Physics , National Sun Yat-Sen University , No. 70 , Lien-Hai Road , Kaohsiung City 80424

3. Siyi Feng

   Xiamen University

   Affiliation as printed

   Department of Astronomy , Xiamen University , Zengcuoan West Road , Xiamen , 361005

4. C. J. Chandler

   National Radio Astronomy Observatory

   Affiliation as printed

   National Radio Astronomy Observatory , PO Box O , Socorro , NM 87801 , USA

5. F. Fontani
6. Nami Sakai

   RIKEN

   Affiliation as printed

   RIKEN Cluster for Pioneering Research , 2-1 , Hirosawa , Wako-shi , Saitama 351-0198 , Japan

7. Y. Oya

   Kyoto University · Yukawa Institute for Theoretical Physics

   Affiliation as printed

   Center for Gravitational Physics , Yukawa Institute for Theoretical Physics , Kyoto University , Oiwake-cho , Kitashirakawa , Sakyo-ku , Kyoto-shi , Kyoto-fu 606-8502 , Japan

8. T. Hanawa

   Chiba University

   Affiliation as printed

   Center for Frontier Science , Chiba University , 1-33 Yayoi-cho , Inage-ku , Chiba 263-8522 , Japan

9. C. Codella

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

   Affiliation as printed

   Istituto Nazionale di Astrofisica (INAF) , Osservatorio Astrofisico di Arcetri , Largo E. Fermi 5 , 50125 Firenze , Italy

   Univ. Grenoble Alpes , CNRS , IPAG , 38000 Grenoble , France

10. Cecilia Ceccarelli

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

    Affiliation as printed

    Univ. Grenoble Alpes , CNRS , IPAG , 38000 Grenoble , France

11. Izaskun Jiménez-Serra

    Consejo Superior de Investigaciones Científicas · Centro de Astrobiología

    Affiliation as printed

    Centro de Astrobiología (CAB) , INTA-CSIC , Ctra. de Torrejón a Ajalvir , km 4 , 28850 , Torrejón de Ardoz , Spain

12. Luca Cacciapuoti

    European Southern Observatory · European Southern Observatory

    Affiliation as printed

    European Southern Observatory , Alonso de Cordova 3107 , Vitacura , Region

13. E. Bianchi

    Arcetri Astrophysical Observatory · National Institute for Astrophysics

    Affiliation as printed

    Istituto Nazionale di Astrofisica (INAF) , Osservatorio Astrofisico di Arcetri , Largo E. Fermi 5 , 50125 Firenze , Italy

14. Mathilde Bouvier Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Lei- den, The Netherlands

15. M. de Simone

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

    Affiliation as printed

    European Southern Observatory , Karl-Schwarzschild Str. 2 , 85748 Garching bei München , Germany

    Istituto Nazionale di Astrofisica (INAF) , Osservatorio Astrofisico di Arcetri , Largo E. Fermi 5 , 50125 Firenze , Italy

16. A. Isella

    Rice University

    Affiliation as printed

    Department of Physics and Astronomy , Rice University , 6100 Main Street , MS-108 , Houston , TX 77005 , USA

17. D Johnstone

    Herzberg Institute of Astrophysics · University of Victoria

    Affiliation as printed

    Department of Physics and Astronomy , University of Victoria , Vic- toria , BC V8P 5C2 , Canada

    NRC Herzberg Astronomy and Astrophysics , 5071 West Saanich Road , Victoria , BC , V9E 2E7 , Canada

18. L. Loinard
19. G. Sabatini

    Arcetri Astrophysical Observatory · National Institute for Astrophysics

    Affiliation as printed

    Istituto Nazionale di Astrofisica (INAF) , Osservatorio Astrofisico di Arcetri , Largo E. Fermi 5 , 50125 Firenze , Italy

20. Yancy L. Shirley

    University of Arizona

    Affiliation as printed

    Steward Observatory , 933 N Cherry Ave. , Tucson , AZ 85721 , USA

21. Y. Aikawa

    The University of Tokyo

    Affiliation as printed

    Department of Astronomy , The University of Tokyo , 7-3-1 Hongo , Bunkyo-ku , Tokyo 113-0033 , Japan

22. María José Maureira

    Max Planck Institute for Extraterrestrial Physics

    Affiliation as printed

    Center for Astrochemical Studies , Max-Planck-Institut für extrater- restrische Physik (MPE) , Gieβenbachstr. 1 , 85741 Garching , Ger - many

23. P. Caselli

    Max Planck Institute for Extraterrestrial Physics

    Affiliation as printed

    Center for Astrochemical Studies , Max-Planck-Institut für extrater- restrische Physik (MPE) , Gieβenbachstr. 1 , 85741 Garching , Ger - many

24. F. Ménard

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

    Affiliation as printed

    Univ. Grenoble Alpes , CNRS , IPAG , 38000 Grenoble , France

25. N. Balucani

    University of Perugia

    Affiliation as printed

    Department of Chemistry, Biology, and Biotechnology , The Univer- sity of Perugia , Via Elce di Sotto 8 , 06123 Perugia , Italy

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 , Toulouse , France

27. S. B. Charnley

    Goddard Space Flight Center

    Affiliation as printed

    Astrochemistry Laboratory , Code 691 , NASA Goddard Space Flight Center , 8800 Greenbelt Road , Greenbelt , MD 20771 , USA

28. Nicolás Cuello

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

    Affiliation as printed

    Univ. Grenoble Alpes , CNRS , IPAG , 38000 Grenoble , France

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 , 95000 , Cergy , France

30. D. Fedele

    Arcetri Astrophysical Observatory · National Institute for Astrophysics

    Affiliation as printed

    Istituto Nazionale di Astrofisica (INAF) , Osservatorio Astrofisico di Arcetri , Largo E. Fermi 5 , 50125 Firenze , Italy

31. T. Hama

    The University of Tokyo

    Affiliation as printed

    Department of Basic Science , The University of Tokyo , 3-8-1 Komaba , Meguro , Tokyo 153-8902 , Japan

    Komaba Institute for Science , The University of Tokyo , 3-8-1 Komaba , Meguro , Tokyo 153-8902 , Japan

32. Eric Herbst

    University of Virginia

    Affiliation as printed

    Department of Chemistry , University of Virginia , McCormick Road , PO Box 400319 , Charlottesville , VA 22904 , USA

33. T. Hirota

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

    Affiliation as printed

    National Astronomical Observatory of Japan , 2-12 Hoshigaoka , Mizusawa , Oshu , Iwate 023-0861 , Japan

    SOKENDAI (The Graduate University for Advanced Studies) , 2-21- 1 Osawa , Mitaka , Tokyo 181-8588 , Japan

34. Bertrand Lefloch

    Universitat Autònoma de Barcelona · Centre National de la Recherche Scientifique · University of Bonn · Université de Bordeaux · University of Electro-Communications · Hokkaido University · Laboratoire d'Astrophysique de Bordeaux · National Astronomical Observatory of Japan · The University of Texas at Austin · University of Bologna

    Affiliation as printed

    Université de Bordeaux -CNRS Laboratoire d'Astrophysique de Bordeaux, 33600 Pessac, France 36 Institut de Radioastronomie Millimétrique, 38406 Saint-Martin d'Hères, France 37 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mi- taka, Tokyo 181-8588, Japan 38 Institute of Low Temperature Science, Hokkaido University, N19W8, Kita-ku, Sapporo, Hokkaido 060-0819, Japan 39 Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain 40 Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan 41 Department of Astronomy, The University of Texas at Austin, 2515 Speedway, Austin, Texas 78712, USA 42 Alma Mater Studiorum -Università di Bologna, Dipartimento di Fisica e Astronomia "Augusto Righi", Via Gobetti 93/2, I-40129, Bologna, Italy 43 Transdisciplinary Research Area (TRA) 'Matter'/Argelander- Institut für Astronomie, University of Bonn 44 Materials Science and Engineering, College of Engineering, S

35. A. Lopez-Sepulcre

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

    Affiliation as printed

    Univ. Grenoble Alpes , CNRS , IPAG , 38000 Grenoble , France

36. Luke T. Maud

    European Southern Observatory

    Affiliation as printed

    European Southern Observatory , Karl-Schwarzschild Str. 2 , 85748 Garching bei München , Germany

37. Anna Miotello

    European Southern Observatory

    Affiliation as printed

    European Southern Observatory , Karl-Schwarzschild Str. 2 , 85748 Garching bei München , Germany

38. G. Moellenbrock

    National Radio Astronomy Observatory

    Affiliation as printed

    National Radio Astronomy Observatory , PO Box O , Socorro , NM 87801 , USA

39. H. Nomura

    The Graduate University for Advanced Studies, SOKENDAI

    Affiliation as printed

    SOKENDAI (The Graduate University for Advanced Studies) , 2-21- 1 Osawa , Mitaka , Tokyo 181-8588 , Japan

40. Y. Oba
    Affiliation as printed

    Metropolitana de Santiago , Chile

41. S. Ohashi

    RIKEN

    Affiliation as printed

    RIKEN Cluster for Pioneering Research , 2-1 , Hirosawa , Wako-shi , Saitama 351-0198 , Japan

42. Y. Okoda

    Herzberg Institute of Astrophysics · RIKEN

    Affiliation as printed

    NRC Herzberg Astronomy and Astrophysics , 5071 West Saanich Road , Victoria , BC , V9E 2E7 , Canada

    RIKEN Cluster for Pioneering Research , 2-1 , Hirosawa , Wako-shi , Saitama 351-0198 , Japan

43. J. E. Pineda

    Max Planck Institute for Extraterrestrial Physics

    Affiliation as printed

    Center for Astrochemical Studies , Max-Planck-Institut für extrater- restrische Physik (MPE) , Gieβenbachstr. 1 , 85741 Garching , Ger - many

44. L. Podio

    Arcetri Astrophysical Observatory · National Institute for Astrophysics

    Affiliation as printed

    Istituto Nazionale di Astrofisica (INAF) , Osservatorio Astrofisico di Arcetri , Largo E. Fermi 5 , 50125 Firenze , Italy

45. A. Rimola
    Affiliation as printed

    Metropolitana de Santiago , Chile

46. T. Sakai
    Affiliation as printed

    Metropolitana de Santiago , Chile

47. D. M. Segura-Cox
    Affiliation as printed

    Metropolitana de Santiago , Chile

48. Brian Svoboda

    National Radio Astronomy Observatory

    Affiliation as printed

    National Radio Astronomy Observatory , PO Box O , Socorro , NM 87801 , USA

49. L. Testi

    Arcetri Astrophysical Observatory · National Institute for Astrophysics

    Affiliation as printed

    Istituto Nazionale di Astrofisica (INAF) , Osservatorio Astrofisico di Arcetri , Largo E. Fermi 5 , 50125 Firenze , Italy

50. 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 , Toulouse , France

51. S. Viti Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Lei- den, The Netherlands

52. N. Watanabe
    Affiliation as printed

    Metropolitana de Santiago , Chile

53. Y. Watanabe
    Affiliation as printed

    Metropolitana de Santiago , Chile

54. Z.-E. Zhang
    Affiliation as printed

    Metropolitana de Santiago , Chile

55. F. O. Alves
    Affiliation as printed

    Metropolitana de Santiago , Chile

56. S. Yamamoto
    Affiliation as printed

    Metropolitana de Santiago , Chile