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HST and Spitzer Observations of the Hd 207129 Debris Ring

Krist, John E. and Stapelfeldt, Karl R. and Bryden, Geoffrey and Rieke, George H. and Su, K. Y. L. and Chen, Christine C. and Beichman, Charles A. and Hines, Dean C. and Rebull, Luisa M. and Tanner, Angelle and Trilling, David E and Clampin, Mark and Gaspar, Andras (2010) HST and Spitzer Observations of the Hd 207129 Debris Ring. Astronomical Journal, 140 (4). pp. 1051-1061. ISSN 1538-3881

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Publisher’s or external URL: http://dx.doi.org/10.1088/0004-6256/140/4/1051

Abstract

A debris ring around the star HD 207129 (G0V; d = 16.0 pc) has been imaged in scattered visible light with the ACS coronagraph on the Hubble Space Telescope (HST) and in thermal emission using MIPS on the Spitzer Space Telescope at lambda = 70 mu m(resolved) and 160 mu m(unresolved). Spitzer IRS (lambda= 7-35 mu m) and MIPS (lambda= 55-90 mu m) spectrographs measured disk emission at lambda > 28 mu m. In the HST image the disk appears as a similar to 30 AU wide ring with a mean radius of similar to 163 AU and is inclined by 60 degrees from pole-on. At 70 mu m, it appears partially resolved and is elongated in the same direction and with nearly the same size as seen with HST in scattered light. At 0.6 mu m, the ring shows no significant brightness asymmetry, implying little or no forward scattering by its constituent dust. With a mean surface brightness of V = 23.7 mag arcsec(-2), it is the faintest disk imaged to date in scattered light. We model the ring's infrared spectral energy distribution (SED) using a dust population fixed at the location where HST detects the scattered light. The observed SED is well fit by this model, with no requirement for additional unseen debris zones. The firm constraint on the dust radial distance breaks the usual grain size-distance degeneracy that exists in modeling of spatially unresolved disks, and allows us to infer a minimum grain size of similar to 2.8 mu m and a dust size distribution power-law spectral index of -3.9. An albedo of similar to 5% is inferred from the integrated brightness of the ring in scattered light. The low-albedo and isotropic scattering properties are inconsistent with Mie theory for astronomical silicates with the inferred grain size and show the need for further modeling using more complex grain shapes or compositions. Brightness limits are also presented for six other main-sequence stars with strong Spitzer excess around which HST detects no circumstellar nebulosity (HD 10472, HD 21997, HD 38206, HD 82943, HD 113556, and HD 138965).

Item Type: Article
Publisher’s Statement: © 2010 American Astronomical Society. IOP Publishing.
ID number or DOI: 10.1088/0004-6256/140/4/1051
Keywords: absolute calibration; beta-pictoris; circumstellar matter; hipparcos catalog; hubble-space-telescope; main-sequence stars; mass stars; mips survey; multiband imaging photometer; pictoris moving group; solar-type stars; stars: individual (HD 207129, HD 10472, HD 21997,
Subjects: Q Science > QB Astronomy
NAU Depositing Author Academic Status: Faculty/Staff
Department/Unit: College of Engineering, Forestry, and Natural Science > Physics and Astronomy
Date Deposited: 30 Sep 2015 16:29
URI: http://openknowledge.nau.edu/id/eprint/368

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