Stars visible to the naked eye typically have angular diameters on the order of one milliarcsecond (mas), while a handful of red supergiants extend for a few tens of mas. Revealing details across and outside stellar surfaces, such as starspots ortransiting exoplanets, requires imaging with resolution measured in tens of micro-arcseconds (mas). The Rayleigh criterion requires kilometer-scale interferometric baselines to achieve this level of angular resolution in the visible waveband. Astronomical imaging with multi-kilometer interferometry has previously been achieved only by radio/sub-mm interferometers such as VLA, ALMA, VLBA, and the Event Horizon Telescope (EHT).
Recent advances in optical telescope design, photodetector efficiency, and high-speed electronic data recording and synchronization have created a new observational capability to achieve unprecedented angular resolution for several thousand bright (m< 6) and hot (O/B/A) stars through a modern implementation of Stellar Intensity Interferometry (SII). During the next decade, arrays of opticaltelescopes will perform SII over multi-kilometer baselines, allowing visible band imaging with an angular resolution better than 40 m arc-sec.
In this talk, I will describe science investigations that will be enabled by m arc-sec astronomical imaging in the visible. This observational capability can provide new insight in a broad range of astrophysical topics including stellar structure and evolution, improvements in exoplanet mass estimation, and the direct imaging of fast stellar rotators and high-mass binary systems. We describe recent advances in the development of the technique, including recent ~500 m arc-sec measurements of stellar diameters performed by the VERITAS-SII observatory in Spring 2019. The talk also describes the expected optical imaging resolution of VERITAS-SII and the future kilometer-baseline CTA IACT Observatory (Canary Islands, Spain and Paranal,Chile). We conclude with potential capabilities of future Very Large Intensity Interferometer (VLII), which could employ a reconfigurable array of optical telescopes deployed in multi-kilometer baselines. VLII would allow field of view and angular resolution to be reconfigured to meet the requirements for specific astronomical targets, analogous to VLA and ALMA.
For more information on the colloquium series of lectures, visit the following link: https://physics.osu.edu/physics-colloquium-schedule
