Observing Transiting Exoplanets: Removing Systematic Errors To Constrain Atmospheric Chemistry And Dynamics
AuthorZellem, Robert Thomas
AdvisorGriffith, Caitlin A.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractThe >1500 confirmed exoplanets span a wide range of planetary masses (~1 M_Earth – 20 M_Jupiter), radii (~0.3 R_Earth – 2 R_Jupiter), semi-major axes (~0.005 – 100 AU), orbital periods (~0.3 – 1 x 10⁵ days), and host star spectral types. The effects of a widely-varying parameter space on a planetary atmosphere's chemistry and dynamics can be determined through transiting exoplanet observations. An exoplanet's atmospheric signal, either in absorption or emission, is on the order of ~0.1% which is dwarfed by telescope-specific systematic error sources up to ~60%. This thesis explores some of the major sources of error and their removal from space- and ground-based observations, specifically Spitzer/IRAC single-object photometry, IRTF/SpeX and Palomar/TripleSpec low-resolution single-slit near-infrared spectroscopy, and Kuiper/Mont4k multi-object photometry. The errors include pointing-induced uncertainties, airmass variations, seeing-induced signal loss, telescope jitter, and system variability. They are treated with detector efficiency pixel-mapping, normalization routines, a principal component analysis, binning with the geometric mean in Fourier-space, characterization by a comparison star, repeatability, and stellar monitoring to get within a few times of the photon noise limit. As a result, these observations provide strong measurements of an exoplanet's dynamical day-to-night heat transport, constrain its CH₄ abundance, investigate emission mechanisms, and develop an observing strategy with smaller telescopes. The reduction methods presented here can also be applied to other existing and future platforms to identify and remove systematic errors. Until such sources of uncertainty are characterized with bright systems with large planetary signals for platforms such as the James Webb Space Telescope, for example, one cannot resolve smaller objects with more subtle spectral features, as expected of exo-Earths.
Degree ProgramGraduate College