Infrared
Fine-Structure Lines Workshop 2025

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The Department of Physics at Winona State University (WSU) is happy to announce a workshop on infrared fine-structure lines. This 4-day conference will take place June 10 - 13, 2025 in the Science Laboratory Center at WSU in Winona, Minnesota, USA. 

The meeting will cover all topics related to the use of the infrared fine-structure lines as probes of the interstellar medium and properties of galaxies. This will include observational results as well as theoretical models and simulations. We aim to assemble a small (~50 - 60 participants) yet diverse group of astronomers including observers, theoreticians, and instrumentalists whose interests span from the earliest epochs to the present day, and galactic ecosystems to our own Milky Way.  

The infrared fine-structure lines (e.g. [CII] 158 µm, [OIII] 88 µm, [OI] 63 µm, [NeII] 12.8 µm, etc.) are powerful probes of the physical conditions of the various ionized, atomic, and molecular phases of the interstellar medium (ISM) in which they arise. They are usually optically thin, weakly affected by extinction due to dust, and important coolants of gas in which they arise. These properties, along with the lines being quite bright, make the IR fine-structure lines important tools in studying the physics of gas and its connection to star formation and AGN both in our own galaxy as well as others from the present day to the earliest epochs of the universe.  

In 2015, a Far-IR Fine-Structure Line Workshop was held at the Haus der Astronomie and Max Planck Institute for Astronomy in Heidelberg, Germany. That workshop, motivated by results at that time from Herschel, ALMA, NOEMA, etc., sought to fully realize the potential of the IR fine-structure lines. Eight years later, our understanding of the lines has significantly improved while the facility landscape is quite different.  JWST is now flying, providing unappareled access to the mid-IR fine-structure lines, while ground-based facilities like ALMA routinely detect the far-IR lines at the earliest epochs. However, we are nearly a decade past the end of Herschel’s mission and SOFIA has been recently decommissioned. Efforts are underway to develop the next generation of space-based far-IR observatory, but for the foreseeable future balloon missions will provide the only access to this important astrophysical window.  

Considering this new reality for infrared astronomy, the 2025 IR Fine-Structure Line Workshop will:  

• Bring together key figures in the observation and modeling of IR fine-structure lines to review our understanding of these emission lines and progress over that last eight years.   

• Identify the key gaps in our understanding of the lines and our ability to use the lines as probes of galaxy properties.   

• Identify the work to be done in the next 5 to 10 years to fill those gaps.   

• Identify how we will do this work given the current facilities landscape, including what precursor work needs to be done to support future space-based missions.   

• Identify synergies outside infrared (optical, radio, etc.) to best leverage the unique capabilities of the IR fine-structure lines.