Understanding the liveliness and volatility of debris disks: from the microscopic properties to causal mechanisms.

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dc.contributor.author Draper, Zachary Harrison
dc.date.accessioned 2018-08-30T16:06:02Z
dc.date.available 2018-08-30T16:06:02Z
dc.date.copyright 2018 en_US
dc.date.issued 2018-08-30
dc.identifier.uri http://hdl.handle.net/1828/9986
dc.description.abstract Debris disks are a fundamental component of exoplanetary systems. Understanding their relationship with host stars and neighboring planets can help contextualize the evolution of exoplanetary systems. In order to further that goal, this thesis addresses some extreme outlier examples of debris disk systems. First, the highly asymmetric debris disk around HD 111520 is resolved and analyzed at multiple wavelengths to create a self-consistent model of the disk thermal emission and scattered light. The best-fit model is proposed to be an asymmetric disk from a recent collision of large, icy bodies on one side of the disk. In contrast, most debris disks are thought to be in a steady collisional cascade and this disk model could represent a relatively rare event in the creation of debris disks. Secondly, an optical spectroscopic survey of stars is conducted on stars where far-infrared observations exist to detect the presence of debris disks. Specifically, AF-type stars are targeted in order to provide context regarding the Lambda Boo phenomenon, where stars are found to be specifically refractory metal-poor. One mechanism for this was hypothesized to be from planetary scattering of debris disks, causing the accretion of volatiles from comets. The findings were that over the entire unbiased sample, stars which were refractory metal poor tended to be the stars with brightest debris disks. This supports a planet-disk hypothesis underlying the accretion of volatile gases, since debris disks undergoing active planetary stirring are brighter. This would mean about 13\% of stars with debris disk are undergoing strong planetary scattering based on the occurrence rate of Lambda Boo stars relative to debris disk stars. These two tacks in our observational understanding of these extreme examples of debris disks provide constraints on the volatility at work. en_US
dc.language English eng
dc.language.iso en en_US
dc.rights Available to the World Wide Web en_US
dc.subject circumstellar disks en_US
dc.subject debris disks en_US
dc.subject exoplanetary systems en_US
dc.subject chemically peculiar stars en_US
dc.title Understanding the liveliness and volatility of debris disks: from the microscopic properties to causal mechanisms. en_US
dc.type Thesis en_US
dc.contributor.supervisor Brenda, Matthews
dc.contributor.supervisor Venn, Kimberley Ann
dc.degree.department Department of Physics and Astronomy en_US
dc.degree.level Doctor of Philosophy Ph.D. en_US
dc.identifier.bibliographicCitation Draper, Z. H., Matthews, B. C., Kennedy, G. M., Wyatt, M. C., Venn, K. A., & Sibthorpe, B. 2016b, Monthly Notices of the RAS, 456, 459 en_US
dc.identifier.bibliographicCitation Draper, Z. H., Matthews, B., Venn, K., Lambert, D., Kennedy, G., & Sitnova, T. 2018, Astrophysical Journal, 857, 93 en_US
dc.description.scholarlevel Graduate en_US

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