Faculty Mentor Information
Dr. James Dull, College of Idaho
Additional Funding Sources
This work was supported with the funding from the National Science Foundation under grant number 2424470.
Presentation Date
7-15-2026
Abstract
Classical Be stars are hot, luminous B-type stars characterized by hydrogen emission lines in their spectra. Among the most rapidly rotating stars known, they spin at 70-80% of their critical velocity, ejecting material into a circumstellar disk that produces these spectral features. Depending on viewing orientation, this can appear as either strong emission or sharp absorption lines. Be star variability arises from several sources, including disk instabilities, extreme rotation, and gravitational interactions with binary companions. To better understand this variability—and more broadly, hot star evolution—we obtained high-resolution H-alpha spectra of three known variable Be stars: 59 Cyg, OT Gem, and Beta Lyrae. We present measurements characterizing the shape and strength of their emission-line profiles. Continued observations will further clarify the mechanisms driving Be star variability and inform broader models of hot-star evolution.
Investigating H-Alpha Variability in Classical Be Stars: β Lyr, 59 Cyg, and γ Cas
Classical Be stars are hot, luminous B-type stars characterized by hydrogen emission lines in their spectra. Among the most rapidly rotating stars known, they spin at 70-80% of their critical velocity, ejecting material into a circumstellar disk that produces these spectral features. Depending on viewing orientation, this can appear as either strong emission or sharp absorption lines. Be star variability arises from several sources, including disk instabilities, extreme rotation, and gravitational interactions with binary companions. To better understand this variability—and more broadly, hot star evolution—we obtained high-resolution H-alpha spectra of three known variable Be stars: 59 Cyg, OT Gem, and Beta Lyrae. We present measurements characterizing the shape and strength of their emission-line profiles. Continued observations will further clarify the mechanisms driving Be star variability and inform broader models of hot-star evolution.