PROJECT-J: The Shocking H 2 Outflow from HH 46

The Astrophysical Journal, vol. 995, pp. 199

Abstract

Abstract We analyze the H 2 emission observed in the HH 46 Class I system as part of PROtostellar JEts Cradle Tested with JWST (PROJECT-J), to investigate the origin and excitation of the warm molecular outflow. We used NIRSpec and MIRI spectral maps (1.6–27.9 μ m) to trace the structure and physical conditions of the outflow. By fitting the H 2 rotational diagrams with a multitemperature gas model, we derived key physical parameters, including temperature, extinction, column densities, and the ortho-to-para ratio. This information is combined with a detailed kinematical analysis and comparison with irradiated shock models. We find no evidence of H 2 temperature or velocity stratification from the axis to the edge of the outflow, as would be expected in MHD disk-wind models and as observed in other outflows. Instead, the observations suggest that the H 2 emission arises from shock interactions of jet bow shocks and/or wide-angle winds with the ambient medium and cavity walls. NIRSpec emission and velocity maps reveal expanding molecular shells, likely driven by the less luminous source in the binary system. We infer an accretion rate of ≲10 −9 M ⊙ yr −1 for the secondary source, approximately one order of magnitude lower than that of the primary. The H 2 emission is consistent with excitation by low-velocity (∼10 km s −1 ) J-type shocks, irradiated by an external UV field that may originate from strong dissociative shocks driven by the atomic jet. Future JWST observations will further constrain the evolution of the expanding shell and the mechanisms driving the outflow.

Authors 16

1. M. G. Navarro corresponding

   Astronomical Observatory of Rome · National Institute for Astrophysics

   Affiliation as printed

   INAF — Osservatorio Astronomico di Roma, Via di Frascati 33, 00078 Monte Porzio Catone, Italy

2. Brunella Nisini corresponding

   Astronomical Observatory of Rome · National Institute for Astrophysics

   Affiliation as printed

   INAF — Osservatorio Astronomico di Roma, Via di Frascati 33, 00078 Monte Porzio Catone, Italy

3. Teresa Giannini corresponding

   Astronomical Observatory of Rome · National Institute for Astrophysics

   Affiliation as printed

   INAF — Osservatorio Astronomico di Roma, Via di Frascati 33, 00078 Monte Porzio Catone, Italy

4. Patrick J Kavanagh corresponding

   National University of Ireland, Maynooth

   Affiliation as printed

   Department of Physics, Maynooth University, Maynooth, Co. Kildare, Ireland

5. A. Caratti o Garatti corresponding

   Astronomical Observatory of Capodimonte

   Affiliation as printed

   INAF—Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Napoli, Italy

6. S. Antoniucci corresponding

   Astronomical Observatory of Rome · National Institute for Astrophysics

   Affiliation as printed

   INAF — Osservatorio Astronomico di Roma, Via di Frascati 33, 00078 Monte Porzio Catone, Italy

7. Héctor G. Arce corresponding

   Yale University

   Affiliation as printed

   Department of Astronomy, Yale University, New Haven, CT 06511, USA

8. F. Bacciotti corresponding

   Arcetri Astrophysical Observatory · National Institute for Astrophysics

   Affiliation as printed

   INAF — Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy

9. S. Cabrit corresponding

   Centre National de la Recherche Scientifique · Observatoire de Paris · Sorbonne Université · Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères · Institut de Planétologie et d'Astrophysique de Grenoble · Université Grenoble Alpes

   Affiliation as printed

   IPAG, Observatoire de Grenoble, Université Grenoble-Alpes, France

   LERMA, Observatoire de Paris-PSL, Sorbonne Université, CNRS, F-75014 Paris, France

10. Deirdre Coffey corresponding

    University College Dublin

    Affiliation as printed

    University College Dublin, School of Physics, Belfield, Dublin 4, Ireland

11. Catherine Dougados corresponding

    Institut de Planétologie et d'Astrophysique de Grenoble · Université Grenoble Alpes

    Affiliation as printed

    IPAG, Observatoire de Grenoble, Université Grenoble-Alpes, France

12. J. Eislöffel corresponding

    Thüringer Landessternwarte Tautenburg

    Affiliation as printed

    Thüringer Landessternwarte, Sternwarte 5, D-07778 Tautenburg, Germany

13. Patrick M. Hartigan corresponding

    Rice University

    Affiliation as printed

    Physics and Astronomy Department, Rice University, 6100 S. Main, Houston, TX 77005-1892, USA

14. L. Podio corresponding

    Arcetri Astrophysical Observatory · National Institute for Astrophysics

    Affiliation as printed

    INAF — Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy

15. Ewine F. van Dishoeck corresponding Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory, Leiden University, PO Box 9513, NL 2300, RA Leiden, The Netherlands

16. Emma T. Whelan corresponding

    National University of Ireland, Maynooth

    Affiliation as printed

    Department of Physics, Maynooth University, Maynooth, Co. Kildare, Ireland