Aims: We characterize the mid-infrared spectrum of the outer regions of the Red Rectangle nebula to probe the carbonaceous dust and molecular content beyond the circumbinary disk. Methods: We present JWST MIRI-MRS observations of the SW whisker, extracted from three distinct environments: the biconical outflow, the whisker itself, and the shadow region outside the outflow. We compare these with an archival ISO-SWS observation of the inner nebula. Results: The JWST spectra display only classical AIB emission on a weak dust continuum, with no signatures of the oxygen-rich circumbinary disk mineralogy nor of the rich molecular emission seen at optical wavelengths. The AIBs are predominantly Class A - in marked contrast to the exclusively Class B profiles previously reported for the inner regions - with systematic differences between the outflow and shadow regions pointing to environmentally driven PAH processing.
@article{arxiv.2603.28923,
title = {JWST MIRI-MRS observations of the Red Rectangle: AIB class transformation in the outer nebula},
author = {A. Ebenbichler and P. Moraga Baez and A. Candian and E. Peeters and J. Cami and P. J. Sarre and A. N. Witt and I. Argyriou and B. Vandenbussche and H. Van Winckel and L. B. F. M. Waters},
journal= {arXiv preprint arXiv:2603.28923},
year = {2026}
}
Comments
6 pages, 4 figures, submitted for publication in Astronomy & Astrophysics