2007ApJ...659.1623C

Using the CHARA Array and the Palomar Testbed Interferometer, the chemically peculiar star λ Boötis has been spatially resolved. We have measured the limb darkened angular diameter to be θ_LD=0.533±0.029 mas, corresponding to a linear radius of R_*=1.70±0.10 R_☉. The measured angular diameter yields an effective temperature for λ Boo of T_eff=8887±242 K. Based on literature surface gravity estimates spanning logg=4.0-4.2 cm/s2, we have derived a stellar mass range of M_*=1.1-1.7 M_☉. For a given surface gravity, the linear radius uncertainty contributes approximately σ(M_*)=0.1-0.2 M_☉ to the total mass uncertainty. The uncertainty in the mass (i.e., the range of derived masses) is primarily a result of the uncertainty in the surface gravity. The upper bound of our derived mass range (logg=4.2, M_*=1.7±0.2 M_☉) is consistent with 100-300 Myr solar metallicity evolutionary models. The midrange of our derived masses (logg=4.1, M_*=1.3±0.2 M_☉) is consistent with 2-3 Gyr metal-poor evolutionary models. A more definitive surface gravity determination is required to determine a more precise mass for λ Boo.