Epsilon Aurigae Campaign 2009
* Basic System Data
* Campaign Members
* 2009 - 2011 Campaign
Newsletter #1
Newsletter #2
Newsletter #3
Newsletter #4
Newsletter #5
* Past News - TBD
* Photometry
Basics
How To
* Single Channel - TBD
* CCDData
UBV 1982 -1988 (zip)
UBV 2003 - Present (zip)
JH Data 2005-2006
* Spectroscopy
Basics
Leadbeatter
Buil
Astroman
Astrosurf
Data
Dale Mais
Lothar Schanne
* Polarimetry
Basics - TBD
How To - TBD
Data - TBD
* References
1982 - 1984 Campaign
Newsletters
NASA Reference 2384
(.pdf 4.9 MB)References
Photometry
Spectroscopy
Interpretation
* Similar Star Systems
* Links
Epsilon Aurigae Star System
The epsilon Aurigae system is among the most interesting eclipsing star systems. It has puzzled astronomers for nearly 200 years. It is a bright star (3rd magnitude) located about 3 degrees southwest of Capella and eclipses once every 27.1 years. It is at the vertex of a triangular group of stars known as "The Kids". Zeta Aurigae, another interesting long-period eclipsing binary, makes up one of the other two stars.
What makes this star system so intriguing is not just its long period but the length of its eclipse, what happens during the eclipse and what happens out-of-eclipse. The eclipse lasts nearly two years which with the 27.1 year period means the eclipsing body must be gigantic. There have been no satisfactory explanations for this. To make matters even more interesting, there seems to be a mid-eclipse brightening. How can this be? One explanation, according to James Kemp, is that the eclipsing body is a giant cloud of gas enclosing two small stars in orbit around each other. These stars sweep out an area in the middle. It would be a bit like a giant donut. This donut must be tilted such that as it eclipses the primary star, the system's total light decreases and the "donut-hole" allows some of the primary star's light to sneak through at mid-eclipse.
To try to unravel this system's mystery, a concentrated effort was undertaken during the 1982-1984 eclipse. Hundreds of astronomers, amateurs and professionals, from around the world, observed the eclipse. Space born satellites observed in the ultraviolet and infrared. Ground based observations were photometric, spectroscopic, and polarmetric. Photometric observations were made with UBV filters, narrow band filters, and at wavelengths into the far infrared. Despite the concentrated efforts, epsilon Aurigae remains a mystery. The secondary eclipse was due to occur around 1996/1997. Detection of the secondary eclipse light variation is on the order of the out-of-eclipse variations. This makes separating the two periods very difficult. An effort is underway to try to predict the pulsations through continuing observations. If these pulsations can be predicted, observation of the secondary eclipse may be possible.
For those astronomers (both professional and amateur) interested, while the next eclipse will not start until August of 2009, now will be a good time to join a campaign and get prepared. Also, more out-of-eclipse observations are needed before the next eclipse.
Epsilon Aurigae is anything but quiet out-of-eclipse. A seasonal 68 day period that seems to be gradually increasing in amplitude is being seen. There are many surprised yet to be found with this interesting star system. Surely, by the end of the next eclipse, astronomy will have unraveled the mystery of epsilon Aurigae.
Epsilon
Aurigae Star System
Schematic Diagram
Web Page Background
Artwork by D. Egge (c)1985, with permission. Shows yellow supergiant (upper right), hemisphere above plane of disk, with putative binary B stars and fictitious jets and asteroids.
