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|Title:||On the Morphology and Chemical Composition of the HR 4796A Debris Disk||Authors:||Rodigas, Timothy J.
Stark, Christopher C.
Debes, John H.
Hinz, Philip M.
Smith, Paul S.
Males, Jared R.
Skemer, Andrew J.
PUGLISI, Alfio Timothy
Follette, Katherine B.
BRIGUGLIO PELLEGRINO, RUNA ANTONIO
|Issue Date:||2015||Journal:||THE ASTROPHYSICAL JOURNAL||Number:||798||Issue:||2||First Page:||96||Abstract:||We present resolved images of the HR 4796A debris disk using the Magellan adaptive optics system paired with Clio-2 and VisAO. We detect the disk at 0.77 μm, 0.91 μm, 0.99 μm, 2.15 μm, 3.1 μm, 3.3 μm, and 3.8 μm. We find that the deprojected center of the ring is offset from the star by 4.76 ± 1.6 AU and that the deprojected eccentricity is 0.06 ± 0.02, in general agreement with previous studies. We find that the average width of the ring is 14<SUP>+3</SUP><SUB>-2</SUB>% (11.1<SUP>+2.4</SUP><SUB>-1.6</SUB> AU), also comparable to previous measurements. Combining our new scattered light data with archival Hubble Space Telescope images at ~0.5-2 μm, along with previously unpublished Spitzer/MIPS thermal emission data and all other literature thermal data, we set out to constrain the chemical composition of the dust grains. After testing 19 individual root compositions and more than 8400 unique mixtures of these compositions, we find that good fits to the scattered light alone and thermal emission alone are discrepant, suggesting that caution should be exercised if fitting to only one or the other. When we fit to both data sets simultaneously, we find that silicates and organics are generally the most favored, while large abundances of water ice are usually not favored. These results suggest the HR 4796A dust grains are similar to interstellar dust and solar system comets, though improved modeling is necessary to place better constraints on the exact chemical composition of the dust. This paper includes data obtained at the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.||Acknowledgments:||We thank the referee, Christian Thalmann, for helpful comments and suggestions. We are grateful to the entire LCO observing support staff for their help preparing and operating the telescope and instruments during the observing runs. We thank the teams at the Steward Observatory Mirror Lab/CAAO (University of Arizona), Microgate (Italy), and ADS (Italy) for building the phenomenal adaptive secondary mirror (ASM) for use in the AO. The MagAO ASM was developed with support from the NSF MRI program. The MagAO pyramid wavefront sensor was developed with help from the NSF TSIP program and the Magellan partners. The Active Optics guider was developed by Carnegie Observatories with custom optics from the MagAO team. The VisAO camera and commissioning was supported with help from the NSF ATI program. C.C.S. would like to acknowledge support of this research by an appointment to the NASA Postdoctoral Program at Goddard Space Flight Center, administered by Oak Ridge Associated Universities through a contract with NASA. J.R.M and K.M.M. were supported under contract with the California Institute of Technology (Caltech) funded by NASA through the Sagan Fellowship Program. P.S.S. acknowledges support from the NASA/JPL contract 1256424 given to the University of Arizona. A.J.W. acknowledges the support of the Carnegie node of the NASA Astrobiology Institute under Cooperative Agreement NNA09DA81A.||URI:||http://hdl.handle.net/20.500.12386/26542||URL:||https://iopscience.iop.org/article/10.1088/0004-637X/798/2/96/meta||ISSN:||0004-637X||DOI:||10.1088/0004-637X/798/2/96||Bibcode ADS:||2015ApJ...798...96R||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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