Water in star-forming regions - Physics and chemistry from clouds to disks as probed by Herschel spectroscopy

Sep 17, 2026

Water is a key molecule in the physics and chemistry of star and planet formation, yet it is difficult to observe from Earth. Using Herschel Space Observatory data, the WISH program combines far-infrared observations of water and related species to map excitation conditions and water abundances across environments. The analysis couples source physical structure with chemical networks and non-LTE radiative transfer to compare models and observations.

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Abstract

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Aims

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Water in star-forming regions: Physics and chemistry from clouds to disks as probed by Herschel spectroscopy Downloaded from: [https://research.chalmers.se](https://research.chalmers.se), 2026-09-17 15:07 UTC Citation for the original published paper (version of record): van Dishoeck, E., Kristensen, L., Mottram, J. et al (2021). Water in star-forming regions: Physics and chemistry from clouds to disks as probed by Herschel spectroscopy. Astronomy and Astrophysics, 648. [http://dx.doi.org/10.1051/0004-6361/202039084](http://dx.doi.org/10.1051/0004-6361/202039084) N. B. When citing this work, cite the original published paper. research.chalmers.se offers the possibility of retrieving research publications produced at Chalmers University of Technology. It covers all kind of research output: articles, dissertations, conference papers, reports etc. since 2004. research.chalmers.se is administrated and maintained by Chalmers Library (article starts on next page) A&A 648, A24 (2021) [https://doi.org/10.1051/0004-6361/202039084](https://doi.org/10.1051/0004-6361/202039084)[ ](https://doi.org/10.1051/0004-6361/202039084)© ESO 2021 &~~t~~ronomy~~t~~rop~~h~~ys~~i~~cs Water in star-forming regions: physics and chemistry from clouds to disks as probed by Herschel spectroscopy E. F. van Dishoeck 1 , 2 , L. E. Kristensen3 , J. C. Mottram4 , A. O. Benz5 , E. A. Bergin6 , P. Caselli2 , F. Herpin7 , M. R. Hogerheijde 1 , 21 , D. Johnstone8 , 9 , R. Liseau 10 , B. Nisini 11 , M. Tafalla 12 , F. F. S. van der Tak 13 , 14 , F. Wyrowski 15 , A. Baudry7 , M. Benedettini 16 , P. Bjerkeli 10 , G. A. Blake 17 , J. Braine7 , S. Bruderer2 , 5 , S. Cabrit 18 , J. Cernicharo 19 , Y. Choi 13 , 20 , A. Coutens7 , Th. de Graauw 1 , 13 , C. Dominik21 , D. Fedele22 , M. Fich23 , A. Fuente 12 , K. Furuya24 , J. R. Goicoechea 19 , D. Harsono 1 , F. P. Helmich 13 , 14 , G. J. Herczeg25 , T. Jacq7 , A. Karska26 , M. Kaufman27 , E. Keto28 , T. Lamberts29 , B. Larsson30 , S. Leurini 15 , 31 , D. C. Lis32 , G. Melnick28 , D. Neufeld33 , L. Pagani 18 , M. Persson 10 , R. Shipman 13 , V. Taquet22 , T. A. van Kempen34 , C. Walsh35 , S. F. Wampﬂer36 , U. Yıldız32 , and the WISH team (Afﬁliations can be found after the references) Received 1 August 2020 / Accepted 14 December 2020 ABSTRACT Context. Water is a key molecule in the physics and chemistry of star and planet formation, but it is difﬁcult to observe from Earth. The Herschel Space Observatory provided unprecedented sensitivity as well as spatial and spectral resolution to study water. The Water In Star-forming regions with Herschel (WISH) key program was designed to observe water in a wide range of environments and provide a legacy data set to address its physics and chemistry. Aims. The aim of WISH is to determine which physical components are traced by the gas-phase water lines observed with Herschel and to quantify the excitation conditions and water abundances in each of these components. This then provides insight into how and where the bulk of the water is formed in space and how it is transported from clouds to disks, and ultimately comets and planets. Methods. Data and results from WISH are summarized together with those from related open time programs. WISH targeted 􀀘 80 sources along the two axes of luminosity and evolutionary stage: from low-to high-mass protostars (luminosities from <1 to > 105 L􀀌 ) and from pre-stellar cores to protoplanetary disks. Lines of H2 O and its isotopologs, HDO, OH, CO, and [O I], were observed with the HIFI and PACS instruments, complemented by other chemically-related molecules that are probes of ultraviolet, X-ray, or grain chemistry. The analysis consists of coupling the physical structure of the sources with simple chemical networks and using non-LTE radiative transfer calculations to directly compare models and observations. Results. Most of the far-infrared water emission observed with Herschel in star-forming regions origina

FAQs

What is the WISH program designed to determine?

WISH aims to identify which physical components are traced by gas-phase water lines observed with Herschel and to quantify excitation conditions and water abundances in each component.

Which instruments and molecular lines were used in the study?

Water and related species such as H2O, HDO, OH, CO, and [O I] were observed with HIFI and PACS, complemented by other molecules probing ultraviolet, X-ray, or grain chemistry.

What do the results indicate about the origin of far-infrared water emission?

Most far-infrared water emission comes from warm outflowing and shocked gas at high density and temperature, heated by kinetic energy dissipation, with compact emission and multiple velocity components.

Sep 17, 2026

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