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R. D. Gehrz (University of Minnesota), N. Smith (University of Colorado)
We present the results of panchromatic imaging studies of the circumstellar nebula around the massive over-contact binary system RY Scuti. HST/STIS and ground-based spectra combined with VLA radio, HST visual, and Keck infrared (IR) images reveal a young, expanding equatorial torus that may have been ejected as recently as 120 years ago (Gehrz et al 1995, ApJ, 439, 417; Smith et al. 1999, AJ, 118, 960; Gehrz et al. 2001, ApJ, 559, 395; Smith, Gehrz, and Goss 2001, AJ, 122, 2700). The IR morphology of the nebula is consistent with the interpretation that we are viewing a limb-brightened equatorial torus nearly edge-on and that the outer regions of the torus are dominated by optically thin, thermal IR emission from silicate dust. Radio continuum emission comes from the inner edge of the torus. This radiaton is due to thermal bremsstrahlung from hot gas ionized by UV radiation from the luminous OB stars that comprise the binary system. Emission from H-alpha, [Ne II] 12.8 microns, and [S III] 9532 Angstroms is co-spatial with the radio emission and interior to the thermal IR dust emission. The expansion age of the nebula is derived by combining multi-epoch H-aplha and radio continuum images, and expansion velocities seen in STIS spectra show a structure consistent with an expanding clumpy ring. We propose a model that accounts for the observational characteristics of the nebula and speculate about the evolutionary state of the system. This work has been supported by NASA and the Graduate School of the University of Minnesota.
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.