"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
"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.