August 11 2016 Meeting

At our August 11th meeting, Michael Packer will give a talk on Globular Clusters...

Observing the Galactic History of Globular Clusters

Abstract: The 160 spherical oceans of stars we call globular clusters (GC's) are the oldest objects orbiting our Miky Way and are progressively reveling a cornucopia  of information concerning our galactic history story. In the early 1900's while mapping GC positions relative to our solar system we learned the "You Are Here" story: that Earth lies in the plain of the Milky Way 26,000 light-years from the galactic core. Now early in the 2000's the growing field of galactic archaeology is showing us that a high fraction of GC's were not born in situ but were accreted from dwarf galaxy collisions. Consequently, cataloging precise GC's properties (star metallicities and ages) with dwarf galaxy star metallicities and ages is giving us a thorough record and timeline of how our galaxy evolved. Some GC's are in fact the core remnants of dwarf galaxies our Milk Way has gravitationally shredded. Globular clusters need aperture, good seeing and dark skies to resolve detail. But once observed under these conditions, GC's reveal an exquisitely rich sea of red giant and fuel spent stars that do not take us back to the Big Bang but rather show us the age of time in its extreme. Michael's talk will cover the general properties GC's and which ones to observe/image for detail. The talk will also show GC formation with some N-particle animation and the role GCs play in the new field of galactic archaeology

Michael is an amateur astronomer of 25 years and lighting engineer designing optics for indoor and outdoor luminaires. He has a Masters of Physics from San Francisco State University and researched efficient lighting at Lawrence Berkeley National Laboratory.