Question

help please


Compare and contrast elliptical and spiral galaxies.

Answer 1

@TheOcean
@Xmoses1

Answer 2

Spiral galaxy is a special kind of galaxy as described by Hubble in his work. It consists of a flat, rotating disk containing Stars, gas and dust and a central concentration of stars known as bulge. These are surrounded much fainter halo of stars many of which reside in globular clusters. They are named for the Spiral structures that extend from the center to the disk. The spiral arms are ongoing sites of formation of stars and are brighter than the surrounding disk because of young hot OB stars that inhabit them. Together with Irregular galaxies they make about 60% of Local Universe. E.g.- NGC1300, UGC12158.

Elliptical galaxy is a galaxy having an approximately ellipsoidal shape and a smooth nearly featureless brightness profile. They range in shape from nearly spherical to highly flat and in size from hundreds millions to over one trillion stars. Most Elliptical galaxy are composed of older, low mass stars, with a sparse interstellar medium and minimal star formation actvity. They are surrounded by a large number of globular clusters. They are believed to make up approximately 10-15% of the galaxies in our local Universe. E.g.- MACSG-1423, Maffei 1 .

~Yahoo.