We report new and archival K-band interferometric uniform disk diameters obtained with the Palomar Testbed Interferometer for the eclipsing binary star ϵ Aurigae, in advance of the start of its eclipse in 2009. The observations were inteded to test whether low amplitude variations in the system are connected with the F supergiant star (primary), or with the intersystem material connecting the star with the enormous dark disk (secondary) inferred to cause the eclipses. Cepheid-like radial pulsations of the F star are not detected, nor do we find evidence for proposed 6% per decade shrinkage of the F star. The measured 2.27 +/- 0.11 milli-arcsecond K band diameter is consistent with a 300 times solar radius F supergiant star at the Hipparcos distance of 625 pc. These results provide an improved context for observations during the 2009-2011 eclipse.
@article{arxiv.0810.5382,
title = {Interferometric Studies of the extreme binary, $\epsilon$ Aurigae: Pre-eclipse Observations},
author = {R. Stencel and M. Creech-Eakman and A. Hart and J. Hopkins and B. Kloppenborg and D. Mais},
journal= {arXiv preprint arXiv:0810.5382},
year = {2010}
}