skip to main content

Title: TEMPERATURE-DEPENDENT INFRARED OPTICAL CONSTANTS OF OLIVINE AND ENSTATITE

Since the Infrared Space Observatory (ISO) mission, it has become clear that dust in circumstellar disks and outflows consists partly of crystalline silicates of pyroxene and olivine type. An exact mineralogical analysis of the dust infrared emission spectra relies on laboratory spectra, which, however, have been mostly measured at room temperature so far. Given that infrared spectral features depend on the thermal excitation of the crystal's vibrational modes, laboratory spectra measured at various (low and high) temperatures, corresponding to the thermal conditions at different distances from the star, can improve the accuracy of such analyses considerably. We have measured the complex refractive index in a temperature range of 10-973 K for one mineral of each of those types of silicate, i.e., for an olivine and an enstatite of typical (terrestrial) composition. Thus, our data extend the temperature range of previous data to higher values and the compositional range to higher iron contents. We analyze the temperature dependence of oscillator frequencies and damping parameters governing the spectral characteristics of the bands and calculate absorption cross-sectional spectra that can be compared with astronomical emission spectra. We demonstrate the usefulness of our new data by comparing spectra calculated for a 100 K dustmore » temperature with the ISO SWS spectrum of IRAS 09425-6040.« less
Authors:
 [1] ;  [2] ;  [3]
  1. National Astronomical Observatory of Japan (NAOJ), 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
  2. Astrophysikalisches Institut und Universitäts-Sternwarte, Schillergässchen 2-3, D-07745 Jena (Germany)
  3. Institut für Astrophysik, Türkenschanzstraße 17, A-1180 Wien (Austria)
Publication Date:
OSTI Identifier:
22364607
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 798; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ASTROPHYSICS; COMPARATIVE EVALUATIONS; COSMIC DUST; CRYSTALS; DAMPING; DISTANCE; EMISSION SPECTRA; ENSTATITE; EXCITATION; INFRARED SPECTRA; IRON; OLIVINE; OSCILLATORS; REFRACTIVE INDEX; SILICATES; STARS; TEMPERATURE DEPENDENCE