June 15, 2010
The odd galaxy NGC 4725 is thought to have only one spiral arm as opposed to the standard two or more arms. Astronomers refer to NGC 4725 as a ringed barred spiral galaxy because a prominent ring of stars encircles a bar of stars at its center (the bar is seen here as a horizontal ridge with faint red features). In contrast, our Milky Way galaxy sports multiple arms and a proportionally smaller bar and ring. In this false-color Spitzer picture, the galaxy's arm is highlighted in red, while its center and outlying halo are blue. Red represents warm dust clouds illuminated by newborn stars, while blue indicates older, cooler stellar populations. The red spokes seen projecting outward from the arm are clumps of stellar matter that may have been pushed together by instable magnetic fields. NGC 4725 is located 41 million light-years away in the constellation Coma Berenices.