Stellar populations of spiral galaxy bulges We are studying the formation sequence of spiral galaxies using the ages of their stars to determine whether the bulges or disks formed first. In the background of this page is the small-bulged spiral galaxy NGC 1637. These galaxies existed when the Universe was only half or a third of its current age. All of the pictures on this page are images from the Hubble Space Telescope. They are galaxies in a cluster seen at a time halfway back to the Big Bang.
Galaxies are big.
Details like spiral arms, bars, and ring shapes have never been seen before at such huge distances. Check out Chapters 4 and 5 of my dissertation , and look for forthcoming preprints here. Check out the published version . Here's a false-color image of the cluster core. The profiles rest heavily on the Berkeley Globular Cluster Survey of King and Djorgovski.