Friday, 13 February, 1998 at 3pm

Joseph Jensen - Gemini

"Infrared Surface Brightness Fluctuations and the Extragalactic Distance Scale"

ABSTRACT: "Infrared surface brightness fluctuations (SBFs) can be used to measure distances to ~7000 km/s and to probe unresolved stellar populations in early-type galaxies. I will describe our work to calibrate the IR SBFs and measure distances to the Hydra and Coma clusters. Our measurement of the Hubble constant H0=87+/-11 km/s/Mpc is consistent with optical SBF studies. We compare our data for 18 ellipticals in the Local Group, Virgo, Fornax, and Eridanus clusters to simple stellar population models and find a signficant spread in the ages of the galaxies in our sample."

NOTE: THIS IS THE FIRST JOINT GEMINI/JAC SEMINAR!