Crystalline Silicate Feature of the Vega-like Star HD 145263

We have observed the 8-13 $\mu$m spectrum (R$\sim$250) of the Vega-like starcandidate HD145263 using Subaru/COMICS. The spectrum of HD145263 shows thebroad trapezoidal silicate feature with the shoulders at 9.3 $\mu$m and 11.44$\mu$m, indicating the presence of crystalline silicate grains. This detectionimplies that crystalline silicate may also be commonly present around Vega-likestars. The 11.44 $\mu$m feature is slightly shifted to a longer wavelengthcompared to the usual 11.2-3 $\mu$m crystalline forsterite feature detectedtoward Herbig Ae/Be stars and T Tauri stars. Although the peak shift due to theeffects of the grain size can not be ruled out, we suggest that Fe-bearingcrystalline olivine explains the observed peak wavelength fairly well.Fe-bearing silicates are commonly found in meteorites and most interplanetarydust particles, which originate from planetesimal-like asteroids. According tostudies of meteorites, Fe-bearing silicate must have been formed in asteroidalplanetesimals, supporting the scenario that dust grains around Vega-like starsare of planetesimal origin, if the observed 11.44 $\mu$m peak is due toFe-bearing silicates.Comment: accepted for Publication in ApJ