Looking far into space is looking back in time. Staff astronomer emeritus Alan Dressler began his career at Carnegie some years ago as a Carnegie Fellow. Today, he and colleagues use Magellan and the Hubble Space Telescope to study galaxy evolution—how galaxy structures and shapes change, the pace and character of star birth, and how large galaxies form from earlier, smaller systems.

Dressler is also intricately involved in instrumentation. He led the effort for the Inamori Magellan Areal Spectrogrph (IMACS), a wide-field imager and multi-object spectrograph which became operational in 2003 on the Baade telescope at Carnegie’s Las Campanas Observatory. Spectrographs take light collected by a telescope and disperse it into a spectrum of wavelengths, which reveals elements of celestial objects.

Dressler was also coprincipal in a project known as “the Morphs,” which focused on the evolution of spiral galaxies over the last 7 billion years. The group found that star formation was more common in galaxies 5 billion years ago than it is today, and that much of this star formation occurred in starbursts, in contrast to the more steady star formation seen today.

With colleagues, Dressler continues working on a new collaboration among others, called the IMACS Cluster Building Survey, which follows the evolution in stellar population and structure, of a large sample of galaxies in the outskirts of distant galaxy clusters. The survey provides spectra of some 2200 galaxies.

Dressler received his B.A. in Physics from the University of California, Berkeley and his Ph.D. in Astronomy from the University of California, Santa Cruz. He was then awarded a Carnegie fellowship, then a Las Campanas fellowship, before becoming a staff astronomer in 1981.