Thermoluminescence of forsterite and fused quartz as a candidate for the extended red emission

Abstract

Abstract-We investigated thermoluminescence of silicates that are of interest in the interstellar and circumstellar medium after irradiation by y-rays and fast neutrons. The silicates are forsterite, orthoenstatite, olivine, quartz, and crystalline silicon. The irradiated enstatite shows weak and broad peaks at 545 and 760 nm. In contrast, irradiated bulk and powder samples offorsterite show strong and broad peaks at 640-660 nm. Although thermoluminescence of bulk forsterite is very similar to the extended red emission (ERE) of the Red Rectangle nebula, irradiated powdered forsterite did not reveal any sharp emission features over the broad band. Further, we investigated the possibility of thermoluminescence of crystalline silicon and found that luminescence scarcely appears. It is emphasized that the prominent carrier of ERE is forsterite and fused quartz.

Crystalline silicate dust around evolved stars

“…We assume that the dust shell is optically thin at infrared wavelengths (which is reasonable because we see the dust features in emission), the grain size distribution of the different dust species is similar to what has been measured in the laboratory ( 2 µm, which also is quite realistic, because the width of the features indicates grains smaller than the wavelength) and that all grains of a given composition have the same (single) temperature (this is probably less realistic, but we only want to get a typical temperature for the dust species and are at the moment not interested in the temperature distribution). A comparison of several laboratory data sets with the observations indicates that the laboratory data of Koike et al (2000b) give a good qualitative match to the observations. We will use this data set for our modelling.…”

“…Figure 4 shows a comparison between forsterite in different environments and 2 laboratory spectra. The forsterite measured by JMD was formed from a melt and probably polycrystalline, while the forsterite measured by Koike et al (2000b) was a single crystal. The polycrystalline forsterite is expected to have defects where the different crystals meet each other.…”

“…The time and temperature in these environments are likely to be sufficient to completely crystallize and get rid of all defects. It seems that this is not the case for young stars, , the comet Hale Bopp (Crovisier et al 1997) and an average of 33 micron complexes of evolved stars with evidence for a disk (Molster et al submitted to A&A), together with 2 laboratory measurements of forsterite one done by JMD and one by Koike et al (2000b). Note the difference in width of the 33.6 micron feature.…”

Shape and lattice distortion effects on infrared absorption spectra of olivine particles

“…The mass absorption coefficients of the Kyoto samples are large as twice as the Jena samples, while the peak widths of the Kyoto samples are narrower than those of the Jena Article published by EDP Sciences samples, especially for the 33 μm feature. Molster et al (2002) proposed that the difference is due to the crystallinity of the measured samples; that is, the Kyoto sample was a single crystal made by the Czochralsky method (Koike et al 2000), while the Jena sample was crystallized from a melt by cooling and is probably polycrystalline (Jäger et al 1998). On the other hand, Koike et al (2006) proposed that the difference is not caused by crystallinity but particle shape.…”

The thermoluminescence of meteorites: A brief 2010 perspective

“…The major conclusion was that while the bulk of these materials is amorphous and difficult to characterize, the TL signal was being produced by forsterite, not feldspar. Forsterite is becoming an increasingly important component of primitive materials (Crovisier et al, 1997;Kloeck et al, 1989;Koike et al, 2002;Steele, 1986;Zolensky et al, 2006). Most recently, Craig and Sears (2010) have found a way to reproducibly and reliably obtain data from 10-15 µm particles of the matrix of the Semarkona meteorite with the hope that it will eventually provide insights into the thermal history of interplanetary dust particles and cometary particles returned from the Stardust mission.…”