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Temporal Variations in The Circumstellar Disks of Be Stars from Analysis of Optical and IR Line Profiles

Gerhartz, Cody J
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1501602656319988

Abstract Details

2017, Doctor of Philosophy, University of Toledo, Physics.
Variable asymmetric double-peaked hydrogen emission line profiles in the optical in classical Be stars have been interpreted as evidence of one-armed density waves (or other density structures) within the circumstellar disks. Contemporaneous optical and IR spectroscopy can provide a means of exploring the density structure of any such density variations as a function of radius, since models have shown in the infrared lines serve as a probe of the inner disk, while the hydrogen alpha line probes a much larger region. While variability has been detected in these stars in the optical spectral region over both short (days to weeks) and longer (months) timescales, the variability of infrared line profiles has not been similarly investigated. Presented are contemporaneous Ritter Observatory and IRTF SpeX (0.8-5.4 microns) spectroscopy of 28 classical Be stars observed between September 2005 and January 2011. The data illustrate a range of line profiles common in Be stars and show significant variability in both the optical and the near-infrared. IR hydrogen line profile variability is found to be similar both in character and variety to that observed in the optical. Several targets show asymmetric line profiles with phase differences between the optical and the IR hydrogen lines at least once. For at least 4 targets, this asymmetry suggests a phase delay between the periodic variation in the \ha\ and the IR hydrogen lines. Three additional targets suggest the same type of phase delay exists between the hydrogen alpha and iron lines. For other targets no evidence of a phase delay is detected, indicating that a variety of disk morphologies may be present. A handful of targets are observed in the process of disk formation or loss.
Karen Bjorkman, Dr. (Advisor)
Rupali Chandar, Dr. (Committee Member)
Michael Cushing, Dr. (Committee Member)
Richard Irving, Dr. (Committee Member)
Donald White, Dr. (Committee Member)
681 p.
Astronomy; Astrophysics
Be star; optical spectra; infrared spectra; Ritter Observatory; IRTF; VR variations; psi per; zeta tau; phase delays; timescales

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Citations

  • Gerhartz, C. J. (2017). Temporal Variations in The Circumstellar Disks of Be Stars from Analysis of Optical and IR Line Profiles [Doctoral dissertation, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1501602656319988

    APA Style (7th edition)

  • Gerhartz, Cody. Temporal Variations in The Circumstellar Disks of Be Stars from Analysis of Optical and IR Line Profiles. 2017. University of Toledo, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1501602656319988.

    MLA Style (8th edition)

  • Gerhartz, Cody. "Temporal Variations in The Circumstellar Disks of Be Stars from Analysis of Optical and IR Line Profiles." Doctoral dissertation, University of Toledo, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1501602656319988

    Chicago Manual of Style (17th edition)

toledo1501602656319988
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© 2017, all rights reserved.
This open access ETD is published by University of Toledo and OhioLINK.