Student-Faculty Programs Office
Summer 2017 Announcements of Opportunity

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Project:  Inhomogeneous cloud coverage and its effect on characterizing exoplanets
Disciplines:  Astronomy/Astrophysics, Planetary Science
Mentor:  Renyu Hu, (JPL), Renyu.Hu@jpl.nasa.gov, Phone: (818) 354-6090
Background:  In 2016 NASA has approved and started the formulation of Wide-Field Infrared Survey Telescope (WFIRST). Equipped with a high-performance coronagraph and adaptive optic systems, WFIRST is expected to measure reflected light from giant exoplanets of nearby stars in the visible and near-infrared wavelengths. The spectra to be obtained by the WFIRST coronagraph are dominated by reflection of clouds in the planets atmosphere, and modulated by absorption of methane and water above the clouds (e.g., Cahoy et al. 2010; Hu 2014). One of the science goals of WFIRST is to measure the cloud properties and the abundances of methane and water in the atmospheres of imaged exoplanets.
Description:  The student will simulate reflection spectra of giant exoplanets at varied star-planet separations. Existing models of reflection spectra assume homogeneous cloud coverage on the planet, and the focus of the project is to explore the effect of inhomogeneous cloud coverage. First, the student will use a well-documented atmospheric chemistry and radiative transfer model (e.g., Hu 2014) to simulate the spectra of varied cloud properties. This will entail modeling the high-cloud region (like the zones in Jupiters atmosphere) and the low-cloud region (like the belts), and obtaining the disk-integrated spectra of a gaseous exoplanet. The student will need to modify certain subroutines of an exisitng code in C. Second, the student will compare the spectra, and fold in realistic noise expectation of a future space telescope, to determine the extent to which unknown cloud coverage will affect our ability to characterize the exoplanet via reflection. The student will then search for the ways to measure the cloud coverage, or the relative contrast between the zones and the belts, potentially by observing at multiple orbital phases. The results of this project are expected to be publishable.
References:  Renyu Hu (2014), Ammonia, Water Clouds and Methane Abundances of Giant Exoplanets and Opportunities for Super-Earth Exoplanets, Report of a quick study of science return from direct-imaging exoplanet missions, commissioned by the NASA Exoplanet Exploration Program on behalf of the WFIRST/AFTA Science Definition Team and the Exo-S and Exo-C Science and Technology Definition Teams (arXiv:1412.7582);
Kerri Cahoy, Mark S. Marley, Jonathan J. Fortney (2010), Exoplanet albedo spectra and colors as a function of planet phase, separation, and metallicity, ApJ, 724, 189.
Student Requirements:  The student should have completed colleague-level courses in physics and mathematics. Experience in MATLAB and the C programming language is desired. Knowledge of astronomy or planetary science is not required.
Location / Safety:  Project building and/or room locations: . Student will need special safety training: No.
Programs:  This AO can be done under the following programs:

  Program    Available To
       SURF    both Caltech and non-Caltech students 

Click on a program name for program info and application requirements.


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Problems with or questions about submitting an AO?  Call Jen Manglos of the Student-Faculty Programs Office at (626) 395-2885.
 
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