Crystalline Silicates in Evolved Stars. I. Spitzer/IRS Spectroscopy of IRAS16456-3542, 18354-0638, and 23239+5754

TL;DR

This study presents high-resolution Spitzer/IRS spectra of three evolved stars, revealing rich crystalline silicate features, especially in IRAS 16456-3542, which has the highest crystalline silicate content reported to date.

Contribution

First detailed infrared spectral analysis of these evolved stars showing dominant crystalline silicates, highlighting the extreme crystalline silicate abundance in IRAS 16456-3542.

Findings

IRAS 16456-3542 has >90% crystalline silicates.

Spectra show enstatite-dominated crystalline silicate features.

First report of such high crystalline silicate content in evolved stars.

Abstract

We report the Spitzer Infrared Spectrograph (IRS) observations of three evolved stars: IRAS 16456-3542, 18354-0638, and 23239+5754. The 9.9--37.2um 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.