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Probing the Circumstellar Disks of Classical Be Stars with Optical and Near-Infrared Spectroscopy

Hesselbach, Erica N.
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1249334993

Abstract Details

2009, 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 the infrared lines serve as a probe of the inner disk, while the Hα 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 (Hα) and IRTF SpeX (0.8-5.4 μm) spectroscopy of 33 classical Be stars observed between September 2005 and January 2008. 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 reversed orientation between the optical and the IR hydrogen lines at least once. For at least one target, and possibly several more, this reversed asymmetry suggests a phase delay between quasi-periodic variation in the Hα and the IR hydrogen 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; line strength in these targets appears to vary at the same time for all lines.
Karen Bjorkman, PhD (Advisor)
Nancy Morrison, PhD (Committee Member)
Steven Federman, PhD (Committee Member)
Thomas Megeath, PhD (Committee Member)
Scott Lee, PhD (Committee Member)
Carol Jones, PhD (Committee Member)
208 p.
Astronomy; Astrophysics
circumstellar disks; Be stars; near-infrared spectroscopy; IRTF; zeta Tauri

Recommended Citations

Citations

  • Hesselbach, E. N. (2009). Probing the Circumstellar Disks of Classical Be Stars with Optical and Near-Infrared Spectroscopy [Doctoral dissertation, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1249334993

    APA Style (7th edition)

  • Hesselbach, Erica. Probing the Circumstellar Disks of Classical Be Stars with Optical and Near-Infrared Spectroscopy. 2009. University of Toledo, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1249334993.

    MLA Style (8th edition)

  • Hesselbach, Erica. "Probing the Circumstellar Disks of Classical Be Stars with Optical and Near-Infrared Spectroscopy." Doctoral dissertation, University of Toledo, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1249334993

    Chicago Manual of Style (17th edition)

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© 2009, all rights reserved.
This open access ETD is published by University of Toledo and OhioLINK.