2015ApJ...800..115T

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 of 0.674±0.014 mas for the limb-darkened angular diameter of this star leads to a physical radius of R_*= 0.9058±0.0190 R_☉ and luminosity of L_*= 0.622±0.014 L_☉when combined with a fit to the spectral energy distribution of the star. Placing these observed values on an Hertzsprung-Russel diagram along with stellar evolution isochrones produces an age of 10.6±4 Gyr and mass of 0.863±0.043 M_☉. We use archival optical echelle spectra of HD 69830 along with an iterative spectral fitting 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 more precise age of 7.5±3 Gyr. Applying the values of stellar luminosity and radius to recent models on the optimistic location of the habitable zone produces a range 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 of 1.95±0.19 AU, which is outside the orbit of all three planets and its asteroid belt.