All of the research supported by this grant either developed or used the techniques of multi-telescope optical interferometry.  This is a method where several telescopes operate in synchronism, achieving the resolving power of a much-larger telescope.  Most of the work was carried out at the CHARA telescope array on Mt. Wilson, north of Los Angeles.  CHARA is a project of Georgia State University's Center for High Angular Resolution Astronomy and is an optical/interferometric array of six telescopes. There, the telescope spacing of 300 meters achieves resolution approximately 100 times better than the Hubble Space Telescope.  The method currently works only for bright stars, and so the applications are for the study of stellar physics as revealed in some of the most familiar targets, such as the stars Betelgeuse and Aldebaran.  As in most of astronomy, multiple techniques are needed for in-depth study, and the programs undertaken in this research also employed the large 10-meter telescope at the Keck Observatory; adaptive optics imaging at the large European telescope, the Very Large Telescope (VLT); optical imaging from the Hubble; and microwave imaging from IRAM, a radio telescope observatory in France.  These programs were directed toward the study of stars in the late stages of evolution, at a time when enormous expansion of the atmosphere and increasingly violent convection and pulsation lead to the ejection of clouds of gas and dust, and the formation of shells and spectacular nebulae.

Some of the grant resources were used to support advances in instrumentation related to high-resolution imaging.  The prototype Fibered Imager for Single Telescope (FIRST) was built in the laboratory and first operated successfully at Lick Observatory. An experimental method for obtaining simultaneous very high spectral resolution and very high spatial resolution was implemented at the CHARA Array and operated over a period of two years, proving the technique but establishing that systematic use will require more sensitive detectors, which are now under development. They are expected to be available in approximately two years.

The method of adaptive optics, allowing a telescope to remove the disturbing optical effects of the atmosphere, is increasingly used on the world's most powerful telescopes. Optical interferometery can benefit from adaptive optics even more effectively than most other instruments. Providing adaptive optics for the CHARA Array will be a major upgrade in capability and sensitivity.  Following several years of planning and prototyping, partially supported by this grant, the CHARA Array adaptive optics program is underway.  Phase I, implementation of infrastructure changes and faint star trackers, is nearing completion.  Phase II, the acquisition of special flexible mirrors for control of the telescope image, is beginning now and is expected to be completed in two years.

This grant was the principal investigator’s primary source of research support for five years and was partial support for three students to participate in the research. These students were able to obtain experience at observatories and gather research materials and results used in their theses. The grant supported scientist and student travel, hardware purchases, and publication costs. Nineteen publications in scientific journals were enabled in whole or in part by this support.

Last Modified: 10/28/2015
Modified by: David R. Silva