Examining the Evolution of Inner Circumstellar Disks
The Keck interferometer is the most powerful instrument currently available in the Navigator Program and is an important precursor to both SIM and TPF. With the unprecedented angular resolution and faint source sensitivity provided by the Keck interferometer, it is possible to study the circumstellar environments of young stars at spatial scales as small as 0.1-0.4 AU and to begin to address a key scientific goal of the Navigator Program: understanding the formation and evolution of planetary systems. For a project working with researchers at Caltech and the Michelson Science Center, I propose to observe a sample of young stars at a variety of stages including FUor-type objects with more active disks and weak-lined T Tauri stars and older stars with weaker disks. With the proposed interferomeric data, I will characterize the presence and distribution of circumstellar material in the inner disk as a function of age and will compare these direct measurements of the inner disks with theoretical models of disks and with the properties inferred from previous unresolved photometric observations.
Jenny is currently a Professor at Arizona State University.
Exploring the Physical and Chemical Environment of Planet Formation
Understanding the formation of planetary systems remains one of astronomy's most rewarding challenges. It represents a significant component of the search for our own cosmic origins, as well as the possibility of life on other worlds. Consequently, it figures prominently in the recommendations of the most recent NRC Decadal Survey for astronomy and astrophysics. Planet formation is tied to the evolution of gas and dust in disks around young stars. Thus, a comprehensive understanding of the physics and chemistry of young circumstellar disks is essential to a complete picture of star and planet formation, yet basic questions about this process remain unanswered. The proposed research program combines many of the advancements and accomplishments of the last few years and will build on previous work (see publication list) using high-resolution near infrared spectroscopy to peer into the inner 50 AU of disks around young stars. This program will address fundamental questions regarding circumstellar disk evolution and its potential for planet formation including: 1. Does the evolution of gas in the inner disk follow the evolution of dust? 2. Is there any evidence of gas/dust stratification in the disk? 3. What is the CO/H2, ratio in the inner disk around young stars? 4. What is the atmospheric composition and lifetime of known exoplanets?
Sean is currently a Professor at Clemson University.
Investigating Early-Type Stars with the Navy Prototype Optical Interferometer
With the recent successful demonstration of the 6-way beam combination, and the soon to be implemented long delay-line extension, the Navy Prototype Optical Interferometer (NPOI) is opening a window of opportunity to study early-type main-sequence stars in ways not possible before. This is because the typically large distances to stars hotter than the Sun require interferometric observations with baselines longer than previously available to resolve their small apparent diameters. I propose to use the NPOI's reconfigurable array, with baselines of up to 437 m, to investigate the circumstellar disks of Be stars and measure the angular diameters of hot main-sequence stars. These observations, which will achieve angular resolution at the sub-milli-arcsecond level, will also be capable of detecting deviations from circular symmetry in rapidly rotating stars. The results of this observational study will have direct influence on the current state-of-the-art models of stellar photospheres and interiors, as well as on our understanding of the formation and variability mechanisms in the circumstellar environments of Be stars.
Christopher is currently a Professor at Central Michigan University.
The NASA Exoplanet Science Institute is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program.
