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.

NEW!

The History and Evolution of the Disk theory for Epsilon Aurigae

* Basic System Data

Star Chart
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* Similar Star Systems

BM Orionis
Zeta Aurigae
EE Cephei
VV Cephei

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Photometric Anaylsis

Spectroscopic Analysis

As of 17 January 2010

Fall 2009/2010 Ingress V Data
Composite Plot

B and U Band Composite Plots

R and I Band Composite Plots

Plot Observer Key

GHO - Golden Hills Observatory, Richard Miles, Dorset, England
JBO - Jim Beckmann Observatory, Paul J. Beckmann, Mendota Heights, MN USA
SGGO - S. Giovanni Gatano al Observatory, Tiziano Colombo, Pisa, Italy
DES - Des Loughney, Edinburgh, Scotland, UK
TP - Tom Pearson, Virgina Beach, Virginia USA
HGL - Hans-Goran Lindberg, Skultuna, Sweden
GVO - Grand View Observtory, Brian E. McCandless, Elkton, MD USA
HPO - Hopkins Phoenix Observatory , Jeff Hopkins, Phoenix, Arizona USA
FJM - Frank J. Melillo, Holtsville, NY USA
RES - Stencel/Long, University of Denver, Denver, Colorado USA
LO - Lindarberg Observatory, Snaevarr Gudmundsson, Hafnarfjordur, Iceland
GS - Gerard Samolyk, Greenfield, Wisconsin, USA
TK - Thomas Karisson, Varaberg Observatory, Sweden
EAO- Elisabeth Observatory of Athens, Iakovos Marios Strikis, Halder (Athens) Greece
RLO - Roosbeek Lake Observatory, Hubert Hautecler, Boutersem Brabant, Belgium
JESO - Jalina Educational Society Observatory, Dr. Mukund Kurtadikar

Note: RJD is Reduced Julian Date, 2,450,000 has been subtracted from it.

Summary of 1982 - 1984 Eclipse

Article
The Very Long Mystery of Epsilon Aurigae
Robert E. Stencel
Sky & Telescope, May 2009 Page 58

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SAS 09 Papers

Epsilon Aurigae, 2009: The eclipse begins
observing campaign status

Epsilon Aurigae
Hydrogen Alpha Emission Line Variation
The Horn Dance

August 2009 Workshops

DSLR Photometry
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( pdf 2.5 MB)

Astronomical Time

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