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RY Scuti: Infrared and radio observations of the mass-loss wind of a massive binary star systemWe report infrared (IR) imaging, IR photometry, IR spectroscopy, optical/IR photopolarimetry, and Very Large Array (VLA) radio observations of the peculiar binary star RY Scuti. These observations provide an unprecedented view of the detailed spatial structure of the equatorial mass-loss wind of a massive, luminous, 'overcontact' binary system. The binary star (0.43 AU separation) is surrounded by a flattened equatorial disk with an outer radius of approximately = 3 x 10(exp 16) cm (2000 AU) that emits strongly in the IR and radio. The inside of the disk is ionized and emits free-free radiation from hydrogen and 12.8 micrometers forbidden-line emission from (Ne II); the outside of the disk emits thermal radiation from silicate dust. Radio continuum emission is also produced in a compact H II region surrounding the binary. The dust may have a polycyclic aromatic hydrocarbon (PAH) component. We use a rudimentary geometric model in which the thermal IR and radio emission from the disk are assumed to arise in a pair of concentric toroidal rings to estimate the physical properties of the disk. The mean radius of the ionized gas toroid is approximately = 1.3 x 10(exp 16) cm (870 AU), and the mean radius of the dust toroid is approximately = 2.2 x 10(exp 16) cm (1470 AU). RY Scuti has a small intrinsic polarization, with the electric vector perpendicular to the equatorial disk, that is probably caused by electron scattering from hot gas close to the central binary. We conclude that neon in the nebula is overabundant with respect to hydrogen and helium by a factor of between 1.6 and 10. Our IR/radio image data suggest that the circumstellar disk is part of an extensive radiation driven mass-loss outflow that is strongly confined to the equatorial plane of the binary system. The sharp spatial separation of the outer dust torous from the inner ionized gas torus confirms earlier suggestions that dust formation in the circumstellar ejecta of very hot stars must occur in regions that are shielded from the hard radiation field.
Document ID
19950051880
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Gehrz, R. D.
(University of Minnesota, Minneapolis, MN United States)
Hayward, T. L.
(Cornell University Ithaca, NY, United States)
Houck, J. R.
(Cornell University Ithaca, NY, United States)
Miles, J. W.
(Cornell University Ithaca, NY, United States)
Hjellming, R. M.
(National Radio Astronomy Observatory, Soccoro, NM United States)
Jones, T. J.
(University of Minnesota, Minneapolis, MN United States)
Woodward, Charles E.
(University of Wyoming, Laramie, WY United States)
Prentice, Ricarda
(NASA Headquarters Washington, DC United States)
Forrest, W. J.
(University of Rochester, Rochester, NY United States)
Libonate, S.
(University of Rochester, Rochester, NY United States)
Date Acquired
August 16, 2013
Publication Date
January 20, 1995
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 439
Issue: 1
ISSN: 0004-637X
Subject Category
Astronomy
Accession Number
95A83479
Distribution Limits
Public
Copyright
Other

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