The Variable Circumstellar Disk of the Classical Be Star theta CrB
Abstract
Classical Be stars have circumstellar disks that produce hydrogen and helium emission lines in their spectra. The formation mechanism for these disks is still poorly understood. One known contributing factor is the fact that these stars are rapidly rotators. There must be other factors however, considering that not all rapidly rotating stars have disks, and in those that do, the disks are known to disappear and reform seemingly randomly. theta Corona Borealis is one such example of a star with a variable disk; however, it has not been well studied over cycles of disk loss and formation. It is believed that its disk faded away in 1970 when the star's apparent magnitude decreased by about fifty percent of its normal brightness. In 2006, the disk started reforming slowly, and then began fading again. In order to understand the underlying mechanism for disk loss and rebuilding, it is important to have information about the timescales for these processes. To that end, we have analyzed the available spectroscopic data collected over a number of years at the Ritter Observatory to determine when, and possibly why, the disk disappeared and is now trying to redevelop. We present our results so far, which have proven to be interesting, and describe our ongoing work to attempt to gain a better understanding of the process that the star is undergoing.
This work has been supported by an NSF REU grant to the University of Toledo.- Publication:
-
American Astronomical Society Meeting Abstracts #217
- Pub Date:
- January 2011
- Bibcode:
- 2011AAS...21733921P