Journal Article

Evolution of the 3.3-μm emission feature in the Red Rectangle

In-Ok Song, T. H. Kerr, J. McCombie and P. J. Sarre

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 346, issue 1, pages L1-L5
Published in print November 2003 | ISSN: 0035-8711
Published online November 2003 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1046/j.1365-2966.2003.07148.x
Evolution of the 3.3-μm emission feature in the Red Rectangle

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Abstract

Medium-resolution infrared spectroscopic observations of the biconical Red Rectangle nebula in the region of the 3.3-μm unidentified infrared (UIR) emission band are reported. The data were recorded at UKIRT using CGS4 and have allowed the peak wavelength, width, profile and intensity of the 3.3-μm feature to be investigated as a function of offset from the central star HD 44179. Analysis of the profile of the feature along the north-western bicone interface shows an evolution from Type 2 to Type 1 in the classification of Tokunaga et al. The 3.3-μm band recorded on-star shows a close fit to a Lorentzian profile, possibly suggesting a single class of carriers. Subtraction of the Lorentzian fit to the on-star spectrum from the spectrum at each offset reveals a new ‘3.28’-μm emission feature that grows in intensity relative to the main 3.3-μm band as a function of distance from the central star. The 3.28-μm emission band at large offset appears to correspond well in wavelength and FWHM with an absorption feature seen towards the Galactic Centre.

Keywords: techniques: spectroscopic; stars: individual: Red Rectangle; ISM: abundances; ISM: lines and bands; ISM: molecules; infrared: ISM

Journal Article.  2686 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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