Dust around Herbig Ae/Be stars: IRAS low resolution spectra

Abstract

IRAS low resolution spectra are presented for 17 Herbig Ae/Be stars. The observed spectral characteristics are correlated with reddening E(B-V) and the spectral type of the star. The silicate emission feature at 9.7 micrometers is found only in the spectra of Herbig Ae/Be stars with E(B-V) less than or = 1.0 and spectral type later than approximately A0 while this feature is in absorption in stars with E(B-V) less than or = 1.0 and spectral type either than approximately A0. The unidentified emission feature at 11.3 micrometers is found in the spectra of stars with spectral type earlier than approximately A0. These observations are interpreted in terms of the composition of dust in the circumstellar environments of Herbig Ae/Be stars.