Oct 3

"The Nature of Interstellar Hydrocarbons: PAHs, HAC, and Fullerene"
Gregory C. Sloan, Cornell University

The discovery of the unidentified infrared (UIR) emission features in 1973 opened a long-unsettled debate. What is the carrier of the UIR features? Currently, agreement is widespread that they arise from polycyclic aromatic hydrocarbons (PAHs), and for good reasons. However, interstellar hydrocarbon grains may have a different composition when they are outside of the harsh radiative fields where UIR emission is usually observed. Shifts in the spectral structure of PAH-like spectra in cooler environments can be explained by an increase in the ratio of aliphatic/aromatic bonds. Aliphatic bonds are more fragile and the first to be destroyed as hydrocarbon grains are photo-processed. Their presence in cooler environments is consistent with the structure of hydrogenated amorphous carbon (HAC), which remains the leading alternative to the PAH model. Each model appears to be valid within the appropriate domain. Finally, fullerenes appear to be the last gasp of interstellar hydrocarbons before they are completely destroyed.

Nov 28

"The Status of the GMT and a Discussion of the Operations Concept White Paper and Early Science Options"
Anita Cochran, University of Texas at Austin

I will detail the current status of the GMT. In addition, I will conduct a discussion of the Scientific Advisory Committee's (of which I am a member) White Paper on Operations Concept. I will distribute this white paper at the start of the week and interested people should read it. There are lots of ideas how the telescope should run and I need user feedback. In addition, the telescope will start doing science with only 2 instruments and 4 mirrors and no AO. I will lead a discussion of the "killer science" that can be done in this mode. Come with ideas.