Transients and Stellar Activity as Revealed by Ultraviolet Diagnostic Tracers
Abstract
Ultraviolet (UV) observations offer unique insights into transient and variable astrophysical phenomena, from the Sun and nearby stars to supernovae and star-forming galaxies. Here, we summarise and review the diagnostic power of the UV spectrum for probing the physical conditions, dynamics and energetics of these events. We trace the historical development of UV astronomy from early satellite missions to the current landscape shaped by the Hubble Space Telescope, the GALaxy Evolution eXplorer, the Neil Gehrels Swift Observatory and AstroSat/UVIT. Particular emphasis is placed on resonance lines such as Mg II h and k, C II, Si IV, C IV and N V, which probe the (solar and) stellar chromosphere and transition region, revealing magnetic heating, shocks and mass loss across stellar types. We examine UV diagnostics of stellar flares, pre-main-sequence activity and rotation--activity correlations, linking them to exoplanetary irradiation and habitability. We then explore the UV view of supernova shock breakout and early-time emission, as well as the far-UV mapping of young stellar populations and hierarchical star formation in the Magellanic Clouds. Together, these aspects illustrate how the UV connects small-scale plasma processes to galactic-scale star formation. Despite remarkable progress, UV transient astronomy remains limited by instrument availability and cadence. Forthcoming missions promise to transform this field by capturing the rapid, luminous phenomena that define the dynamic Universe.
Related
- Exploring stellar evolution with Luminous Red Novae and Interacting Gap Transients
- Tidal disruption of stellar binaries as a pathway to exotic transients
- Tidal disruption of stellar binaries as a pathway to exotic transients
- First Pre-peak Ultraviolet Spectrum of a Tidal Disruption Event: A Fast Outflow Revealed Prior to Maximum Light in TDE2025aarm
- Extreme Stellar Death and Galaxy Feedback at z = 2: A Rest-frame Ultraviolet Characterization of the Strongly Lensed Superluminous Supernova 2025wny
BibTeX
@misc{grijs2026transients,
title = {{Transients and Stellar Activity as Revealed by Ultraviolet Diagnostic Tracers}},
author = {Richard de Grijs and Martin A. Barstow and Deepak Chahal and Fabio Favata and Xiaoting Fu and Ana I. Gómez de Castro and Sipra Hota and Firoza Sutaria},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.19313},
eprint = {2610.19313},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.19313},
}
RIS
TY - UNPB
TI - Transients and Stellar Activity as Revealed by Ultraviolet Diagnostic Tracers
AU - Richard de Grijs
AU - Martin A. Barstow
AU - Deepak Chahal
AU - Fabio Favata
AU - Xiaoting Fu
AU - Ana I. Gómez de Castro
AU - Sipra Hota
AU - Firoza Sutaria
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2610.19313
UR - https://arxiv.org/abs/2610.19313
AB - Ultraviolet (UV) observations offer unique insights into transient and variable astrophysical phenomena, from the Sun and nearby stars to supernovae and star-forming galaxies. Here, we summarise and review the diagnostic power of the UV spectrum for probing the physical conditions, dynamics and energetics of these events. We trace the historical development of UV astronomy from early satellite missions to the current landscape shaped by the Hubble Space Telescope, the GALaxy Evolution eXplorer, the Neil Gehrels Swift Observatory and AstroSat/UVIT. Particular emphasis is placed on resonance lines such as Mg II h and k, C II, Si IV, C IV and N V, which probe the (solar and) stellar chromosphere and transition region, revealing magnetic heating, shocks and mass loss across stellar types. We examine UV diagnostics of stellar flares, pre-main-sequence activity and rotation--activity correlations, linking them to exoplanetary irradiation and habitability. We then explore the UV view of supernova shock breakout and early-time emission, as well as the far-UV mapping of young stellar populations and hierarchical star formation in the Magellanic Clouds. Together, these aspects illustrate how the UV connects small-scale plasma processes to galactic-scale star formation. Despite remarkable progress, UV transient astronomy remains limited by instrument availability and cadence. Forthcoming missions promise to transform this field by capturing the rapid, luminous phenomena that define the dynamic Universe.
ER -