AAVSO: American Association of Variable Star Observers

Proposal #57

Proposer (15617) Barber Observatory University of Illinois Springfield (jmart5@uis.edu) obscode: UIS01
Assigned To(3663) Dirk Terrell
Date SubmittedNov. 20, 2015

Between 2009 -- 2011 the Citizen Sky Project (www.citizensky.org) monitored the eclipse of Epsilon Aurigae. The Henry R. Barber Observatory at the University of Illinois Springfield participated in that campaign by taking spectra of the star on a regular basis. During that campaign it became evident that the primary star in that system exhibits some interesting out of eclipse fluctuations that have never been well characterized. The primary star is an F-type super giant that may be at an advanced evolutionary state (Hoard et.al, 2010 + Sadakane et al. 2010) with an extensive P-cygni like wind structure (Mourard etc al. 2012). A good understanding of the activity of the primary star itself is critical to account for the spectra vacation in the primary when probing the nature of the unseen companion with spectra during the eclipse.

We have continued to take regular spectra of Epsilon Auriga at the Barber Observatory. The preliminary results and analysis of the last four years of data were presented as a poster by Jarrett & Foster (2015, JAAVSO, 43, 105) at the 103rd Annual Meeting of the AASO in November 2014. Continued monitoring by the AAAVSO Bright Star Monitors reveals fluctuation in brightness with a period of about 70 days. The spectra reveal variations on a comparable time scale in iron absorption lines along with a significant longer term trends over the last four years in the evolution of H-alpha and Na I 589 nm. Over that time period the absorption/emission profile of H-alpha has changed dramatically hinting at the dramatic wind structure observed by Mourard etc al. (2012, A&A, 544, 91).

Our monitoring has been useful for discerning long term trends but it has been sporadic and less sensitive to shorter period variations. A season or two of more consistent monitoring on a bi-weekly basis would provide a better sampling to analyze the data for fluctuations coincident with the ~70 day photometric fluctuations observed by the Bright Star Monitors (BSM). The LISA spectrograph mounted on TMO61 should be able to get a visual spectrum with good signal to noise using a reasonably short exposure time for this target. The cost for the observations is low. Any individual observation should not contribute much. But the time domain coverage over multiple observation seasons has the potential to reveal important trends and patterns. Variations in H-alpha should be detected at the resolution of the LISA spectrograph. It is less certain but possible that these spectra would be sensitive to variations in the K I 769 nm feature as well as the Na I 589 nm feature.

Target RA (H.HH) Dec (D.DD) Magnitude Telescope Observation Frequency Expiration Date Proprietary Term
Epsilon Aurigae 5.032814 43.82331 3.8–2.9 No


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