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Image of Fomalhaut Dust Ring at 350 Microns: The Relative Column Density Map Shows Pericenter-Apocenter AsymmetryWe have imaged the circumstellar disk of Fomalhaut at 350 mm wavelength, using SHARC II (Submillimeter High Angular Resolution Camera II) at the Caltech Submillimeter Observatory. The spatial resolution of the raw images (9") has been enhanced by a factor of 3 using the HiRes deconvolution procedure. We find that at this wavelength and signal-to-noise ratio (approx.12), the observed morphology is that of a simple inclined ring (i approx. 70 deg), with little or no other apparent structure--this is the first observation that shows clearly the ring morphology of the disk. We have combined our 350 mm data with Spitzer Space Telescope images at 24, 70, and 160 mm in order to estimate the two-dimensional spatial variation of relative column density ("tau map") using our DISKFIT procedure. The tau map is based on the following physical assumptions: (1) the wavelength variation of opacity is the same throughout the disk, (2) the radial variation of dust temperature is dictated by the energy balance of individual grains in the stellar radiation field, and (3) the vertical scale height of the disk follows a power-law radial variation. The results confirm the ringlike morphology but also show that the geometric center is displaced from the star by about 8 AU and that the ring has an apocentric enhancement of approximately 14% in integrated column density. If we interpret the displacement in terms of elliptical orbital motion due to gravitational perturbation by an unseen planet, then the implied forced eccentricity is ~0.06; dynamical modeling then predicts an apocentric density enhancement consistent with that inferred from the tau map.
Document ID
20070034782
Acquisition Source
Jet Propulsion Laboratory
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Marsh, K. A.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Velusamy, T.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Dowell, C. D.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Grogan, K.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Beichman, C. A.
(California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 24, 2013
Publication Date
January 12, 2005
Publication Information
Publication: The Astrophysical Journal Letters
Publisher: American Astronomical Society
Volume: 620
Subject Category
Astronomy
Funding Number(s)
CONTRACT_GRANT: NSF AST-02-29008
Distribution Limits
Public
Copyright
Other
Keywords
Fomalhaut
circumstellar matter
planetary systems
stars

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