Identification of three new protoplanetary nebulae exhibiting the unidentified feature at 21 [mu]m

• Published in: Proceedings of the International Astronomical Union Vol. 7; no. S283; p. 328
• Main Authors: Cerrigone, Luciano, Hora, Joseph L, Umana, Grazia, Trigilio, Corrado, Hart, Alexa, Fazio, Giovanni
• Format: Journal Article
• Language: English
• Published: Cambridge Cambridge University Press 01.07.2011
• Subjects: Astronomy; Astrophysics; Nebulae; Stars & galaxies
• ISSN: 1743-9213; 1743-9221
• DOI: 10.1017/S174392131201126X

Abstract Since its discovery, the feature at 21 μm has been detected in all C-rich proto-PNe of intermediate spectral type (A-G) and - weakly - in a few PNe and AGB stars, but the nature of its carriers remains unknown. In this paper, we show the detection of this feature in the spectra of three new stars obtained with the Spitzer Space Telescope. In the attempt to relate the unidentified feature to other dust features, we retrieved mid-IR spectra of all the 21 μm sources currently known from ISO and Spitzer archives and noticed a correlation between the flux emitted in the 21 μm feature and that emitted at 7 and 11 μm (PAH bands and HAC broad emission). Such a correlation may point to a common nature of the carriers. [PUBLICATION ABSTRACT]