CfA OIR Division Lunch Talks

April 22, 1999 Pratt Conference Room, Perkin G-04, 12:30 pm

Dust in Elliptical Galaxies

Dr. Michael Wise, MIT


Contrary to historical viewpoints, it is clear from optical and infrared observations that elliptical galaxies contain substantial amounts of dust. A recent survey of HST data on ellipticals from Cycle 1-3 indicate that 60%-80% of all ellipticals exhibit central dust features. However, estimates for the amount of dust based on such optically visible structures account for only 1%-10% of the total amount of dust detected by IRAS. The remainder of the dust seen by IRAS may be present either in a smooth, diffuse component or at larger radii. Dust in the cores of ellipticals can have a dramatic impact on the observed properties of these systems and their interpretation. In effect, all broad-band observations of elliptical galaxy cores may be age-metallicity-dust degenerate. Such distributions could complicate our understanding of the dynamical evolution of the central regions of these objects. In this talk, I will discuss the results of some recent theoretical models of dusty elliptical galaxies and illustrate the effects such dust populations can have on their observed broad-band properties. I'll show some examples based on HST observations and discuss the prospects for unraveling this triple degeneracy.