Confirmation of C60 in the Reflection Nebula NGC 7023

Abstract

The fullerene C 60 has four infrared active vibrational transitions at 7.0, 8.5, 17.5 and 18.9 μ m. We have previously observed emission features at 17.4 and 18.9 μ m in the reflection nebula NGC 7023 and demonstrated spatial correlations suggestive of a common origin. We now confirm the identification of these features with C 60 by detecting a third emission feature at 7.04 ± 0.05 μ m at a position of strong 18.9 μ m emission in NGC 7023. We also report the detection of these three features in the reflection nebula NGC 2023. We show with spectroscopic mapping of NGC 7023 that the 18.9 μ m feature peaks on the central star, that the 16.4 μ m emission feature due to PAHs peaks between the star and a nearby photodissociation front, and that the 17.4 μ m feature is a blend of a PAH feature and C 60 . The derived C 60 abundance is consistent with that from previous upper limits and possible fullerene detections in the interstellar medium.