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The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII): The Infrared at High Angular Resolution
Wednesday, May 22, 2019 - 3:30pm PDT
Infrared observations have provided critical information for understanding the processes by which stars form. Much of this understanding is derived from observations of low-mass protostars forming in relative isolation, and yet the majority of stars in our galaxies have formed in dense clusters. Unfortunately, while a panoply of different facilities have been used to explore these clusters, there remains a critical gap in the observations — spatially-resolved spectroscopy. The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) is designed to fill this gap. Using a double-Fourier technique, the 8-meter interferometric baseline of BETTII enables differentiation of sources with subarcsecond separations, while the instrument simultaneously serves as a Fourier Transform Spectrometer to obtain low-resolution (R<100) spectra of these sources. Data from BETTII will sample the peak of the Spectral Energy Distribution of closely-spaced protostars in clusters, helping us understand their coevolution and providing a test for theories of clustered star formation. At the same time, BETTII is a technical pathfinder, demonstrating the system-level operation of a “free-flying” interferometer. While the next generation of large space telescopes hold significant promise, many significant scientific questions require higher angular resolution than possible with these facilities or with any feasible space-based single-aperture telescope. To open this new discovery space, space-based interferometers will be needed; BETTII marks a significant step down the path towards these powerful new observatories.