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We used the CHARA Array to directly measure the angular diameter of HD 69830,home to three Neptune mass planets and an asteroid belt. Our measurement of0.674+/-0.014 milli-arcseconds for the limb-darkened angular diameter of thisstar leads to a physical radius of R$_*$ = 0.9058$\pm$0.0190 R\sun andluminosity of L* = 0.622+/-0.014 Lsun when combined with a fit to the spectralenergy distribution of the star. Placing these observed values on anHertzsprung-Russel (HR) diagram along with stellar evolution isochronesproduces an age of 10.6+/-4 Gyr and mass of 0.863$\pm$0.043 M\sun. We usearchival optical echelle spectra of HD 69830 along with an iterative spectralfitting technique to measure the iron abundance ([Fe/H]=-0.04+/-0.03),effective temperature (5385+/-44 K) and surface gravity (log g = 4.49+/-0.06).We use these new values for the temperature and luminosity to calculate a moreprecise age of 7.5+/-Gyr. Applying the values of stellar luminosity and radiusto recent models on the optimistic location of the habitable zone produces arange of 0.61-1.44 AU; partially outside the orbit of the furthest known planet(d) around HD 69830. Finally, we estimate the snow line at a distance of1.95+/-0.19 AU, which is outside the orbit of all three planets and itsasteroid belt.

Stellar Parameters for HD 69830, a Nearby Star with Three Neptune Mass Planets and an Asteroid Belt