Open AccessEvolution of the 3.3‐μm emission feature in the Red Rectangle
Author(s) -
Song InOk,
Kerr T. H.,
McCombie J.,
Sarre P. J.
Publication year - 2003
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-2966.2003.07148.x
Subject(s) - physics , astrophysics , wavelength , full width at half maximum , rectangle , emission spectrum , infrared , nebula , astronomy , optics , spectral line , stars , geometry , mathematics
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.