The unusual silicate dust around HV 2310, an evolved star in the LMC

Abstract

The spectrum of HV 2310, an evolved star in the Large Magellanic Cloud, taken with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope reveals the presence of an optically thin shell of silicate dust with unusual spectral structure in the 10 um feature, with an emission peak at 9.7 um, a saddle at 10.4 um, and an extended shoulder to 11.2 um. This structure is similar to spectra from crystalline silicate grains, and of the available optical constants, forsterite provides the best fit. The spectrum also shows structure at 14 um which may arise from an unidentified dust feature.