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Crystalline Silicate Feature of the Vega-like star HD145263

Mitsuhiko Honda·Hirokazu Kataza·Yoshiko K. Okamoto·Takashi Miyata·Takuya Yamashita·Shigeyuki Sako·Takuya Fujiyoshi·Meguru Ito·Yoko Okada·Itsuki Sakon·Takashi Onaka
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Abstract

We have observed the 8-13 $μ$m spectrum (R$\sim$250) of the Vega-like star candidate HD145263 using Subaru/COMICS. The spectrum of HD145263 shows the broad trapezoidal silicate feature with the shoulders at 9.3 $μ$m and 11.44 $μ$m, indicating the presence of crystalline silicate grains. This detection implies that crystalline silicate may also be commonly present around Vega-like stars. The 11.44 $μ$m feature is slightly shifted to a longer wavelength compared to the usual 11.2-3 $μ$m crystalline forsterite feature detected toward Herbig Ae/Be stars and T Tauri stars. Although the peak shift due to the effects of the grain size can not be ruled out, we suggest that Fe-bearing crystalline olivine explains the observed peak wavelength fairly well. Fe-bearing silicates are commonly found in meteorites and most interplanetary dust particles, which originate from planetesimal-like asteroids. According to studies of meteorites, Fe-bearing silicate must have been formed in asteroidal planetesimals, supporting the scenario that dust grains around Vega-like stars are of planetesimal origin, if the observed 11.44 $μ$m peak is due to Fe-bearing silicates.

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Mitsuhiko Honda, Hirokazu Kataza, Yoshiko K. Okamoto, Takashi Miyata, Takuya Yamashita, Shigeyuki Sako, Takuya Fujiyoshi, Meguru Ito, Yoko Okada, Itsuki Sakon, Takashi Onaka. 2004-06-23. Crystalline Silicate Feature of the Vega-like star HD145263. https://doi.org/10.1086/423242

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