The galaxy color–magnitude diagram shows the relationship between absolute magnitude, luminosity, and mass of galaxies. A preliminary description of the three areas of this diagram was made in 2003 by Eric F. Bell et al. from the COMBO-17 survey that clarified the bimodal distribution of red and blue galaxies as seen in analysis of Sloan Digital Sky Survey data and even in de Vaucouleurs' 1961 analyses of galaxy morphology Noticed in this diagram are three main features: the red sequence, the green valley, and the blue cloud. The red sequence includes most red galaxies which are generally elliptical galaxies. The blue cloud includes most blue galaxies which are generally spirals. In between the two distributions is an underpopulated space known as the green valley which includes a number of red spirals. Unlike the comparable Hertzsprung–Russell diagram for stars, galaxy properties are not necessarily completely determined by their location on the color–magnitude diagram. The diagram also shows considerable evolution through time. The red sequence earlier in evolution of the universe was more constant in color across magnitudes and the blue cloud was not as uniformly distributed but showed sequence progression.
Famous quotes containing the words galaxy and/or diagram:
“for it is not so much to know the self
as to know it as it is known
by galaxy and cedar cone,
as if birth had never found it
and death could never end it:”
—Archie Randolph Ammons (b. 1926)
“If a fish is the movement of water embodied, given shape, then cat is a diagram and pattern of subtle air.”
—Doris Lessing (b. 1919)