Why do elliptical galaxies appear predominantly red or yellow in astronomical observations?
Answer
They are dominated by older, lower-mass stars that have been present for a long time
The reddish and yellowish hue of elliptical galaxies is a direct result of their stellar population. These galaxies lack the necessary gas and dust to fuel the creation of new, hot, blue stars. Consequently, the light we perceive is emitted by long-lived, lower-mass stars that have existed for eons, indicating that the star-formation process has essentially ceased within these systems.
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