A Leap in Sensitivity for CHARA/CLASSIC Optical Interferometry for Astronomy

Georgia State University Research Foundation, Inc., Atlanta GA

Investigators

Abstract

Optical interferometry uses an array of smaller telescopes connected together to achieve the angular resolution of telescopes many hundreds of meters across. Such interferometers have the resolution of extremely large telescopes but have the sensitivity of small telescopes. They can see stars in exquisite detail but can so far only see relatively bright stars. The main goal of this project is to improve the sensitivity of one of these interferometers called the Center for High Angular Resolution Astronomy (CHARA) Array, which is located at Mount Wilson Observatory. Renovations to the camera, optical glass, and data recording will enable studying stars 10 times fainter than currently possible. Such improved sensitivity will enable investigations that may inform whether life may exist elsewhere in the universe, and open up new areas of research. This program will also include new facilities in the CHARA visitor center, which hosts 15,000 visitors each year, and a collaboration with the American Museum of Natural History to display current science bulletins at the CHARA visitor center. The CHARA Array longest baseline yields angular diameter measurements as small as 0.7 mas in K band improving to 0.2 mas at R. CHARA can resolve stellar disks all along the main sequence from O- to M-types, whereas there will be no main sequence stars resolvable by the next generation of single aperture telescopes. The most significant problem in ground based interferometry is sensitivity. This program will increase the limit of the CLASSIC/CLIMB beam combiner by 2 magnitudes in the near infrared. This will be achieved by replacing the 20-year-old PICNIC detector with a modern SELEX MOVPE SAPHIRA based detection system. This upgrade will also include spectral resolution in both H and K bands, simultaneous observation in both bands, and a polarization split. With enhanced sensitivity it will be possible to survey a much broader range of stellar diameters and temperatures, the disks around young stars, winds from massive stars, interacting and detached binary stars, transient events, as well as open up new opportunities for guest observers through the community access program funded by NSF/MSIP. More sensitivity will also vastly expand the ability to observe the cores of Active Galactic Nuclei (AGN). The CHARA could directly confirm or deny a binary structure in an AGN core for the first time. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.