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Asteroid Belts in Debris Disk Twins: Vega and FomalhautVega and Fomalhaut are similar in terms of mass, ages, and global debris disk properties; therefore, they are often referred to as debris disk twins. We present Spitzer 10-35 micrometers spectroscopic data centered at both stars and identify warm, unresolved excess emission in the close vicinity of Vega for the first time. The properties of the warm excess in Vega are further characterized with ancillary photometry in the mid-infrared and resolved images in the far-infrared and submillimeter wavelengths. The Vega warm excess shares many similar properties with the one found around Fomalhaut. The emission shortward of approximately 30 micrometers from both warm components is well described as a blackbody emission of approximately 170 K. Interestingly, two other systems, Eri and HR 8799, also show such an unresolved warm dust using the same approach. These warm components may be analogous to the solar system s zodiacal dust cloud, but of far greater mass (fractional luminosity of approximately 10(exp-5) to 10(exp-6) compared to 10(exp-8) to 10(exp-7). The dust temperature and tentative detections in the submillimeter suggest that the warm excess arises from dust associated with a planetesimal ring located near the water-frost line and presumably created by processes occurring at similar locations in other debris systems as well. We also review the properties of the 2 micrometers hot excess around Vega and Fomalhaut, showing that the dust responsible for the hot excess is not spatially associated with the dust we detected in the warm belt.We suggest it may arise from hot nano grains trapped in the magnetic field of the star. Finally, the separation between the warm and cold belt is rather large with an orbital ratio greater than or approximately 10 in all four systems. In light of the current upper limits on the masses of planetary objects and the large gap, we discuss the possible implications for their underlying planetary architecture and suggest that multiple, low-mass planets likely reside between the two belts in Vega and Fomalhaut.
Document ID
20130014398
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
doi:10.1088/0004-637X/763/2/118
Authors
Su, Kate Y. L. (Arizona Univ. Tucson, AZ, United States)
Rieke, George H. (Arizona Univ. Tucson, AZ, United States)
Malhortra, Renu (Arizona Univ. Tucson, AZ, United States)
Stapelfeldt, Karl R. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hughes, A. Meredith (California Univ. Berkeley, CA, United States)
Bonsor, Amy (Grenoble Univ. France)
Wilner, David J. (Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Balog, Zoltan (Max-Planck-Inst. fuer Astronomie Heidelberg, Germany)
Watson, Dan M. (Rochester Univ. NY, United States)
Werner, Michael W. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Misselt, Karl A. (Arizona Univ. Tucson, AZ, United States)
Date Acquired
August 27, 2013
Publication Date
February 1, 2013
Publication Information
Publication: The Astrophysical Journal
Volume: 763
Issue: 2
Subject Category
Astrophysics
Report/Patent Number
GSFC-E-DAA-TN7789
Funding Number(s)
CONTRACT_GRANT: NAS5-1255094
CONTRACT_GRANT: NNX11AF73G
CONTRACT_GRANT: NNG06EO9A
CONTRACT_GRANT: OTKA No. K82966
CONTRACT_GRANT: NAS5-1256424
Distribution Limits
Public
Copyright
Public Use Permitted.

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