A Symmetric Bipolar Nebula Around MWC 922
P. G. Tuthill1* and
J. P. Lloyd2
We report regular and symmetric structure around dust-enshrouded Be star MWC 922 obtained with infrared imaging. Biconical lobes that appear nearly square in aspect, forming this "Red Square" nebula, are crossed by a series of rungs that terminate in bright knots or "vortices," and an equatorial dark band crossing the core delimits twin hyperbolic arcs. The intricate yet cleanly constructed forms that comprise the skeleton of the object argue for minimal perturbation from global turbulent or chaotic effects. We also report the presence of a linear comb structure, which may arise from optically projected shadows of a periodic feature in the inner regions, such as corrugations in the rim of a circumstellar disk. The sequence of nested polar rings draws comparison with the triple-ring system seen around the only naked-eye supernova in recent history: SN1987A.
1 Physics Department, University of Sydney, NSW 2006, Australia.
2 Department of Astronomy, Cornell University, Ithaca, NY 14853, USA.
* To whom correspondence should be addressed. E-mail: p.tuthill{at}physics.usyd.edu.au
