elliptical galaxy
Quick Summary
Elliptical galaxies are a type of galaxy characterized by their generally elliptical shape and lack of apparent internal structure or spiral arms. They exhibit complete rotational symmetry, appearing as figures of revolution with two equal principal axes and a third, smaller axis presumed to be the axis of rotation.12
The surface brightness of elliptical galaxies decreases monotonically outward from the center. These galaxies do not contain interstellar dust or bright, young stars (spectral types O and B), but they may have low-density gas in their nuclear regions. Their light primarily comes from old stars, particularly evolved red giants, giving them a red color.2
Elliptical galaxies are classified by their apparent shape using the designation En, where n is an integer indicating their flatness. An E0 galaxy appears perfectly circular, while an E7 is significantly flatter.2
Ask Britannica AI about this topic
Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.
