Ultraviolet Properties of Stellar Populations in Galaxies
Summary
The ultraviolet (UV) spectrum of a galaxy serves as a sensitive probe of its stellar content, revealing both the presence of young, massive stars and the signatures of rare evolutionary stages within older populations. Far-ultraviolet (FUV) emission, originating at wavelengths shorter than ~200 nm, traces hot, short-lived O and B stars as well as extreme horizontal branch stars in quiescent systems. Near-ultraviolet (NUV) light, from ~200–300 nm, captures a blend of hot evolved stars and the youngest main-sequence populations. In early-type galaxies a pronounced UV upturn arises from a minority of hot, helium-enriched horizontal branch stars, while residual star formation in both isolated and group environments imprints itself as ring-like or clumpy UV structures at galaxy peripheries. The overall spectral energy distribution (SED) from FUV through the infrared encodes a galaxy’s star formation history, chemical enrichment and dust content, and underpins quantitative estimates of star formation rates (SFRs). Ultraviolet diagnostics are now central to studies of cosmic star formation, galaxy quenching and the mapping of stellar populations across morphological types, offering a global perspective on galaxy evolution and the role of environment in regulating both quiescence and episodic rejuvenation.
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Ultraviolet Properties of Stellar Populations in Galaxies publication trend
The graph below shows the total number of articles in ultraviolet properties of stellar populations in galaxies across all publications each year (not limited to Nature Index journals).
Technical terms
Far-ultraviolet (FUV): Electromagnetic radiation at wavelengths shorter than approximately 200 nm, sensitive to hot massive and evolved stars.
Near-ultraviolet (NUV): Radiation in the 200–300 nm range, tracing both young main-sequence stars and hot evolved populations.
Spectral energy distribution (SED): The flux of a galaxy as a function of wavelength, encoding its star formation history, metallicity and dust content.
Horizontal branch: A phase of stellar evolution characterised by core helium burning, some stars of which become hot enough to emit strongly in the UV.
UV upturn: An unexpected rise in a galaxy’s UV flux at short wavelengths, typically seen in old, metal-rich systems due to hot subpopulations.
Sérsic index: A parameter describing the radial profile of a galaxy’s surface brightness; lower values indicate more extended, disk-like light distributions.
Star formation rate (SFR): The mass of gas converted into stars per unit time, often estimated from UV or Hα luminosity.
References
- Probing the Stellar Populations and Star Formation History of Early-type Galaxies at 0. The Astrophysical Journal (2024).
- Dorado and its member galaxies. Astronomy & Astrophysics (2022).
- Insights into the Evolution of Five Isolated Galaxies. The Astrophysical Journal (2022).
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