Elliptical galaxies. I

Elliptical galaxies are spheroidal stellar systems with smooth luminosity profiles which contain old, metal rich stars. They have a large range in sizes. Usually, rotation is unimportant in ellipticals, unlike for spirals. They often contain low density, very hot gas that emits X-rays. The properties of this hot gas, and also the stellar dynamics, suggest that also in ellipticals most of the mass is in dark matter.