JOYS: Disentangling the warm and cold material in the high-mass IRAS 23385+6053 cluster

¹ Max Planck Institute for Extraterrestrial Physics, Gießenbachstraße 1, 85749 Garching bei München, Germany
e-mail: gieser@mpe.mpg.de
² Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
³ Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
⁴ European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
⁵ Department of Experimental Physics, Maynooth University-National University of Ireland Maynooth, Maynooth, Co Kildare, Ireland
⁶ INAF-Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Napoli, Italy
⁷ Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, D02 XF86 Dublin, Ireland
⁸ UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
⁹ Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden
¹⁰ Laboratory for Astrophysics, Leiden Observatory, Leiden University, PO Box 9513, NL 2300 RA Leiden, The Netherlands
¹¹ Centro de Astrobiologia (CAB, CSIC-INTA), Carretera de Ajalvir, 8850 Torrejon de Ardoz, Madrid, Spain
¹² Department of Astrophysics, University of Vienna, Türkenschanzstr. 17, 1180 Vienna, Austria
¹³ ETH Zürich, Institute for Particle Physics and Astrophysics, Wolfgang-Pauli-Str. 27, 8093 Zürich, Switzerland
¹⁴ Université Paris-Saclay, Université de Paris, CEA, CNRS, AIM, 91191 Gif-sur-Yvette, France
¹⁵ Department of Astronomy, Oskar Klein Centre, Stockholm University, 106 91 Stockholm, Sweden
¹⁶ Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, Bus-2410, 3000 Leuven, Belgium

Received: 31 May 2023
Accepted: 18 September 2023

Abstract

Context. High-mass star formation occurs in a clustered mode where fragmentation is observed from an early stage onward. Young protostars can now be studied in great detail with the recently launched James Webb Space Telescope (JWST).

Aims. We study and compare the warm (>100 K) and cold (<100 K) material toward the high-mass star-forming region (HMSFR) IRAS 23385+6053 (IRAS 23385 hereafter) combining high-angular-resolution observations in the mid-infrared (MIR) with the JWST Observations of Young protoStars (JOYS) project and with the NOrthern Extended Millimeter Array (NOEMA) at millimeter (mm) wavelengths at angular resolutions of ≈0.″2–1.″0.

Methods. We investigated the spatial morphology of atomic and molecular species using line-integrated intensity maps. We estimated the temperature and column density of different gas components using H₂ transitions (warm and hot component) and a series of CH₃CN transitions as well as 3 mm continuum emission (cold component).

Results. Toward the central dense core of IRAS 23385, the material consists of relatively cold gas and dust (≈50 K), while multiple outflows create heated and/or shocked H₂ and show enhanced temperatures (≈400 K) along the outflow structures. An energetic outflow with enhanced emission knots of [Fe II] and [Ni II] suggests J-type shocks, while two other outflows have enhanced emission of only H₂ and [S I] caused by C-type shocks. The latter two outflows are also more prominent in molecular line emission at mm wavelengths (e.g., SiO, SO, H₂CO, and CH₃OH). Data of even higher angular resolution are needed to unambiguously identify the outflow-driving sources given the clustered nature of IRAS 23385. While most of the forbidden fine structure transitions are blueshifted, [Ne II] and [Ne III] peak at the source velocity toward the MIR source A/mmA2 suggesting that the emission is originating from closer to the protostar.

Conclusions. The warm and cold gas traced by MIR and mm observations, respectively, are strongly linked in IRAS 23385. The outflows traced by MIR H₂ lines have molecular counterparts in the mm regime. Despite the presence of multiple powerful outflows that cause dense and hot shocks, a cold dense envelope still allows star formation to further proceed. To study and fully understand the spatially resolved MIR properties, a representative sample of low- and high-mass protostars has to be probed using JWST.