Crystalline silicates in evolved stars. I. Spitzer/infrared spectrograph spectroscopy of IRAS 16456-3542, 18354-0638, and 23239+5754

Abstract

We report the Spitzer Infrared Spectrograph (IRS) observations of three evolved stars: IRAS 16456-3542, 18354-0638, and 23239+5754. The 9.9-37.2 μm Spitzer/IRS high-resolution spectra of these three sources exhibit rich sets of enstatite-dominated crystalline silicate emission features. IRAS 16456-3542 is extremely rich in crystalline silicates, with >90% of its silicate mass in crystalline form, the highest to date ever reported for crystalline silicate sources. © 2013. The American Astronomical Society. All rights reserved..