What characterizes the stellar population and resulting hue of Elliptical galaxies?

Dominated by older, redder stars, giving a generally yellowish-red hue

Elliptical galaxies represent systems that have largely ceased significant star production, often as a result of past major mergers that consumed or expelled their raw materials. Because star formation requires cold gas and dust, and these components are scarce in ellipticals, the population remaining is skewed heavily toward aged stars. These older stars are generally less massive, cooler, and emit light predominantly in the redder wavelengths of the spectrum. This collective light output results in the observed characteristic uniform, overall yellowish-red coloration when these galaxies are viewed.