Studying the Architecture and Dynamics of nearby Habitable Zones through Observations of Exozodiacal Dust
Dr. Steve Ertel
University of Arizona
Exozodiacal dust is warm and hot dust in the inner regions of planetary systems, including the Habitable Zone (HZ). This dust presents both a scientific opportunity for present-day studies of nearby HZs and a potential programmatic obstacle for future exo-Earth imaging missions. Programmatically, scattered light from significant amounts of HZ dust and clumpy disk structures create photon noise and confusion, which need to be taken into account for the design of an exo-Earth imaging mission. Scientifically, the dust is the component of a star's HZ environment that is the most readily detectable through direct methods (as compared to indirect methods such as planetary transit or radial velocity measurements). Observations of the dust can be used to trace the presence and dynamics of its parent bodies (comets, asteroids). This allows us to study the environment in which rocky, habitable zone planets exist and to gauge their potential for actually being habitable as compared to, e.g., barren or water worlds. Exozodiacal dust is best observed in thermal emission due to the better contrast relative to the star, but the dust-to-star flux ratio is still too small to detect the dust’s excess emission photometrically. It thus needs to be spatially resolved to disentangle its emission from the star’s, and the small angular scales involved (1au at 10pc corresponds to 0.1arcsec) require the use of precision interferometry. I will review the current state of exozodiacal dust observations performed with a range of infrared interferometers with particular focus on the recent results from the Large Binocular Telescope Interferometer. I will present our current knowledge of the dust and its implications for exo-Earth imaging, discussing both obstacles and opportunities. I will then discuss the road ahead and the challenges we are facing to study exozodiacal dust in the coming decade both as precursor science and as preparatory science for a future large space observatory attempting to image exo-Earths.
Hosted by Dr. Spalding
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