2022ApJ...939...86T

HD 44179 is a postasymptotic giant branch star with a biconical nebula known as the Red Rectangle. It shows the 3.3, 3.4, 6.2, 7.7, 8.6, and 11.3 μm infrared emission features (commonly known as the polycyclic aromatic hydrocarbon (PAH) emission bands and the Aromatic Infrared Bands). Previous observations of HD 44179 showed that the width of the 3.3 μm emission feature was narrower within 2″ of HD 44179 and wider further away from the star. This was interpreted as an indication that the 3.3 μm emission feature arises from two types of PAHs with spatially varying relative abundances. With new observations of HD 44179 taken with the NASA Infrared Telescope Facility we find that the width of the 3.3 μm emission feature profile is not narrower on HD 44179 and conclude that there is no evidence for two spatially varying components.