Mass loss and circumstellar environments of supernovae

Determine the mechanisms driving mass loss in massive stars, characterize the elemental abundance and ionization of supernova circumstellar media, establish the diversity of ultraviolet supernova spectra, quantify the contribution of ultraviolet emission to the shock-power budget of circumstellar-interacting supernovae, and determine the interstellar-medium properties of supernova host environments.

Background

Early ultraviolet spectroscopy of circumstellar-interacting supernovae can reveal narrow emission and absorption lines produced by the progenitor wind. These features encode the density, ionization, composition, and mass-loss history of the circumstellar medium shortly before explosion.

The paper notes that high-resolution early-time UV observations are largely unavailable because of limitations in sensitivity, cadence, and target-of-opportunity access. A future UV spectrograph could resolve these features and connect progenitor mass loss to supernova diversity and shock energetics.

References

High-resolution, UV spectroscopy of SNe with instruments that have higher sensitivity than HST will enable fundamental questions to be answered about the origins and properties of CSM-interacting SNe: What mechanisms drive mass-loss in massive stars? What is the elemental abundance and ionization of CSM in SNe? What is the UV spectral line diversity of SNe? How does UV emission contribute to the shock power budget of SNe interacting with CSM? What are the ISM properties of SN host environments?

— The future of high-resolution UV spectroscopy: Science with a UV Échelle spectrograph on the Habitable Worlds Observatory, or a dedicated mission  (2609.09329 - Cia et al., 8 Sep 2026) in Section 4, subsection “Supernovae,” under “The Future of Supernova UV Spectroscopy”

However, due to the lack of spectroscopic observations shortly after explosion, this scenario cannot be directly confirmed from the spectra.

— SN 2025aedz: A typical short-plateau type IIP supernova with rapid post-peak decline  (2609.29139 - Wang et al., 24 Sep 2026) in Section 6, subsection “Progenitor and formation channel”

A major open problem from observations of SNe is elucidating the evolution of massive stars in their final years-to-centuries, characterized by erratic variability and episodic mass loss, while quantifying the impact of binary companions and/or the host environment on these phenomena.

— Extragalactic Multi-Band Exploration of Red Supergiants (EMBERS): Pipeline, Source Classification, and Bolometric Properties of 101,219 Red Supergiants from James Webb Space Telescope Imaging  (2609.19344 - Suresh et al., 16 Sep 2026) in Section 1, Introduction

The physical mechanism(s) behind the elevated terminal mass loss and fraction of RSGs undergoing such mass loss is not well understood.

— Extragalactic Multi-Band Exploration of Red Supergiants (EMBERS): Pipeline, Source Classification, and Bolometric Properties of 101,219 Red Supergiants from James Webb Space Telescope Imaging  (2609.19344 - Suresh et al., 16 Sep 2026) in Section 6.4, “Identifying Potential Supernovae Progenitors Before Explosion”

Despite its importance, the physical mechanism driving mass-loss in RSGs remains poorly understood \citep[for a review, see e.g.][]{Decin}.

— Wolf-Rayet formation through L/M-dependent superwinds  (2610.01953 - McKeown et al., 1 Oct 2026) in Section 1, Introduction