2011-09-16

speckle imaging; what is a galaxy?

I spent the morning with Fergus working on fitting a dumb model to Ben Oppenheimer's (AMNH) coronographic imaging of possibly-planet-hosting stars. Oppenheimer's instrument is not just a coronograph but an integral field spectrograph, so there is a huge amount of information in the wavelength-dependence of the residual light from the primary star. Fergus and I worked on building a simple model of it, hoping to increase the sensitivity to faint planets.

At lunch, Beth Willman (Haverford, long-term visitor at NYU) made the case that part of the definition of a galaxy (yes, believe it or not, people are currently arguing about how to define a galaxy; see, eg, Willman 1) ought to involve the chemical abundances of the stars. This is a beautiful, simple, and convincing idea.

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