This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)
Studying the surface details of stars like our sun has been very limited because of their small angular sizes due to their great distances. Astronomers know that sunspots (or starspots) are common, but little detail is known except for the sun itself. Is our sun like other stars? Are we living in an unusual time in the sun's life or is it typical of that of other stars? Can we expect and even predict changes to the sun's surface that may affect our weather and climate? To try to answer these questions, astronomers must increase the resolution of telescopes to see fine details on the surfaces of other stars. Dr. Matthew Muterspaugh of Tennessee State University has designed a new optical camera that will improve the resolution of an interferometer, a special kind of telescope that is made up of several small telescopes spread apart over distances in excess of 100 meters. His camera will be put on the Navy Prototype Optical Interferometer located near Flagstaff, Arizona and it will improve the Interferometer's ability to see fine detail by a factor of 10. This will enable astronomers, for the first time, to see the details on the surfaces of other stars like our sun Dr. Muterspaugh's work is funded by NSF's Major Research Instrumentation program through the Division of Astronomical Sciences.
VISION--the Visible Imaging System for Interferometric Observations at NPOI--is a powerful new camera for precision measurements with spatial resolution 200X sharper than what is possible with the Hubble Space Telescope. This high resolution imaging device will be a powerful tool supporting space situational awareness and defining an astrometric grid for autonomous guidance systems. It will be a versatile tool for high resolution astronomical imaging, allowing stars to be imaged directly with several resolution elements (pixels) across their structures. VISION improves the quality and reliability of observable data products from NPOI, by a factor of ~10, greatly increasing the science capabilities of this NRL-USNO facility. This factor arises from an improved ability to calibrate data. VISION's improved mechanical stability, use of spatial fringe modulation, incorporation of spatial filtering, and photometric taps enables data calibration at a level better than 1%. The VISION hardware has been successully deployed to and intergrated with the NPOI facility. Starlight fringes have been obtained with 4 telescopes simultaneously, indicating the successful phasing of the telescope array and the controls required for science operations. The improved reliability and versatility of the new system has been demonstrated, including the improved ability to isolate spectral features. The intellectual merit of the proposed activity is in the science of stellar astrophysics and development of advanced imaging technologies. The VISION hardware is completed and performance levels have been verified for enabling the direct imaging of the surfaces of stars, teaching us about the structures and shapes. Its demonstrated versatility indicates it can be used for a wide range of multi-purpose high resolution imaging studies. Broader impacts of the research include training 5 undergraduate students from diverse backgrounds in scientific research, optical instrumentation, and control system development. A postdoctoral scholar had a leading role in the instrument's development, training a new scientist in coordinating a team effort. VISION will have an impact beyond the science realm, with its demonstrated versatility indicating it is also useful for space situational awareness applications of interest to the military.
