On the origin of the 19.5 µm feature identifying circumstellar Mg-Fe-oxides

Autor(en)

Thomas Posch, Franz Kerschbaum, Harald Mutschke, Johann M. Dorschner, Cornelia Jäger

Abstrakt

We report the detection of a broad, prominent 19.5 œm dust emission feature in ISO-SWS spectra. It is especially conspicuous in the spectra of low mass-loss AGB stars belonging to the variability classes SRb and Lb with relatively high photospheric temperatures. The feature carrier is proposed to be Mg0.1Fe0.9O, a solid solution of MgO (periclase) and FeO (wustite). This dust species has cubic crystal symmetry like spinel, the carrier of the 13, 16.8 and 31.8 œm spectral features, together with which the 19.5 œm feature is being observed. A broad emission plateau between 11 and 15 œm, which is attributable to amorphous Al2O3, is also detected together with the 19.5 œm and the spinel features. As a consequence of our discovery, we postulate the existence of a distinct class of circumstellar shells, dominated by oxide and not by silicate dust.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Friedrich-Schiller-Universität Jena

Journal

Astronomy & Astrophysics

Band

393

Seiten

7-10

Anzahl der Seiten

4

ISSN

0004-6361

Publikationsdatum

2002

Peer-reviewed

Ja

ÖFOS 2012

105116 Mineralogie, 103003 Astronomie

Link zum Portal

https://ucris.univie.ac.at/portal/de/publications/on-the-origin-of-the-195-m-feature-identifying-circumstellar-mgfeoxides(f0c5601d-c4d2-4a96-8308-0feb88305d73).html