ASTEROID BELTS IN DEBRIS DISK TWINS: VEGA AND FOMALHAUT
- Steward Observatory, University of Arizona, 933 N Cherry Avenue, Tucson, AZ 85721 (United States)
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)
- Code 667, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
- Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
- UJF-Grenoble 1/CNRS-INSU, Institut de Planetologie et d'Astrophysique de Grenoble (IPAG), UMR 5274, Grenoble, F-38041 (France)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
- Max-Planck-Institut fuer Astronomie, Koenigstuhl 17 D-69117, Heidelberg (Germany)
- Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States)
Vega 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 {mu}m 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 {approx}30 {mu}m from both warm components is well described as a blackbody emission of {approx}170 K. Interestingly, two other systems, {epsilon} 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 {approx}10{sup -5} to 10{sup -6} compared to 10{sup -8} to 10{sup -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 {mu}m 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 {approx}>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.
- OSTI ID:
- 22167116
- Journal Information:
- Astrophysical Journal, Vol. 763, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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