Dissertation
A spectroscopic study of the symbiotic star AG Draconis
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Spring 2025
DOI: 10.25820/etd.007964
Abstract
We present high-resolution X-ray spectroscopy of the symbiotic star system AG Draconis (AG Dra) using the Low Energy Transmission Grating Spectrograph (LETGS) on board the Chandra X-ray Observatory. AG Dra is the brightest symbiotic system in the X-ray, with soft X-ray flux nearly twice that of the next brightest system, making it an ideal laboratory to study symbiotic stars. We fit the the spectrum of AG Dra with an absorbed blackbody model and measure the absorption, temperature, and luminosity of the hot component of the system. In addition, we detect emission lines from ionized S, P, Mg, and Fe. We explore evidence for an accretion disk surrounding the white dwarf, with wind accretion and a collisional plasma component, and find our results are consistent with theoretical simulations of symbiotic systems like AG Dra, which predict the formation of an accretion disk that accretes mass through Bondi-Hoyle-Lyttleton accretion.
Details
- Title: Subtitle
- A spectroscopic study of the symbiotic star AG Draconis
- Creators
- Kristie A Nault
- Contributors
- Casey DeRoo (Advisor)Kenneth Gayley (Committee Member)David Nataf (Committee Member)Todd Hillwig (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Physics (Astronomy)
- Date degree season
- Spring 2025
- DOI
- 10.25820/etd.007964
- Publisher
- University of Iowa
- Number of pages
- ix, 56 pages
- Copyright
- Copyright 2025 Kristie A Nault
- Language
- English
- Date submitted
- 04/29/2025
- Description illustrations
- illustrations (some color)
- Description bibliographic
- Includes bibliographical references (page 49-56).
- Public Abstract (ETD)
We observed the symbiotic star system AG Draconis (AG Dra) using the Low Energy Transmission Grating Spectrograph (LETGS) on board the Chandra X-ray Observatory. AG Dra is the brightest symbiotic system in the X-ray, with soft X-ray flux nearly twice that of the next brightest system, making it an ideal laboratory to study symbiotic stars. We fit the the blackbody spectrum of AG Dra and measured the absorption, temperature, and luminosity of the white dwarf component. In addition, we measured emission lines from ionized S, P, Mg, and Fe. We explored evidence for an accretion disk surrounding the white dwarf, with wind accretion and a collisional plasma component, and find our results are consistent with theoretical simulations of symbiotic systems like AG Dra.
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984831021202771
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