Elliptical galaxies can be spherical to flat.
The edges of elliptical galaxies become more and more sparse
until they merge right into space. Elliptical galaxies are mostly
made up of old stars, which come in huge ranges of size, mass and
brightness. The interstellar
medium of elliptical galaxies is complex. It contains gas
which is dotted with clouds of hydrogen, which may be as hot as
180 million degrees Fahrenheit.
Elliptical galaxies are designated by type E. They are
sub-categorized from there by the numbers 0 through 7, depending
on how spherical or football shaped the galaxy is. For example,
an E0 would be a spherical shaped elliptical galaxy, while an E7
would be an elliptical galaxy that looks like an elongated
football. An E4 would be an elliptical galaxy with a shape
somewhere in-between a sphere and a football.
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