Astrophysics Luncheon Seminar
Resolving Stars and their Environments with Optical Interferometry
Presented by Paul Nunez
Jet Propulsion Laboratory, California Institute of Technology
Monday, February 23, 2015
12:00 noon in 169-336
Optical long-baseline interferometry now allows to view stars as extended objects, and also to probe the complex circumstellar environments near the habitable zone. We are using the Center for High Angular Resolution Astronomy (CHARA) to study hot dust within a fraction of an AU of stellar photospheres, which will further our understanding of exo-planet formation and detectability. The "cornerstone" of optical interferometry is the acquisition of interference fringes between two separate apertures, which contain information about the surface brightness distribution of stars. While much can be learned from the analysis of fringes, in order to obtain model-independent images, it is desirable to coherently combine light from tens to hundreds of telescopes. I will describe a couple of alternatives for doing interferometry with a large number of telescopes: one such proposal is known as the Hypertelescope: essentially a diluted optical version of the Arecibo telescope, and currently under development in a high Alpine valley. In addition, I will discuss the interpretation of interferometry in terms of correlations between different space-time points of the wave-front. By exploiting higher orders of correlation we can measure classical interferometric observables while being insensitive to atmospheric turbulence and optical imperfections. I will discuss efforts to perform Intensity (as opposed to Amplitude) interferometry with large arrays of telescopes.