The Mysterious White Dwarf G29-38: Can Magnetically Supported Outflows Explain the 10 micron Excess Emission in its Spectral Energy Distribution? Open Access

Hill, Shannon (Spring 2018)

Permanent URL: https://etd.library.emory.edu/concern/etds/j67313813?locale=en
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Abstract

The spectral energy distribution of variable white dwarf G29-38 has an unusually strong near infrared emission feature as well as a strong 10-micron silicate feature. Previous models have attempted to explain G29-38’s SED characteristics through various dusty disk and toroidal geometries, yet it is unclear how these models would be physically supported. As such, we investigate for the first time how the magnetic properties of G29-38 could result in magnetically supported outflows as modeled by disk winds and x-winds. We construct 72 different disk wind and x-wind models; highlighting models with novel geometries where the magnetic truncation radius is larger than the sublimation radius and the disk size scales with the Roche limit of corresponding planetary objects that we assume is the origin of the dust. We show how well the models reproduce the spectral features of G29-38 and also discuss their relevancy for the white dwarf system. We find that magnetically supported outflows do effectively simulate the spectral energy distribution features for the system, and that this proof of concept will motivate future work to further constrain the models for a more accurate picture. 

Table of Contents

Chapter I. Introduction                                                          1

Chapter II. The Development of G29-38's Outflow Models     5

        Wind Types                                                            5

        Disk Winds                                                             5

        X-winds                                                                8

        Model Paramters                                                       10

                Inner Boundary                                                 10

                Scaling the Outter Boundary and Mass of Models      14 

               Wind Thickness and Disk Thickness                               17 

Chapter III. Methodology                                                        17 

         Monte Carlo Radiative Transfer                                          17

         Spectral Energy Distribution                                             18

         Bining and Zoning                                                      18

         Resolution                                                             19

         Disk Models                                                            20

Chapter IV. Results                                                              20

Chapter V. Discussion                                                            36

        Angle of Inclination                                                      36

        Outflows and Rotations                                                   40

Chapter VI. Conclusions and Discussions for Future Work                            41

Appendix A.                                                                     43

References.                                                                     50

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