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dc.contributor.authorPoteet, Charles A.
dc.contributor.authorChen, Christine H.
dc.contributor.authorHines, Dean C.
dc.contributor.authorPerrin, Marshall
dc.contributor.authorDebes, John H.
dc.contributor.authorPueyo, Laurent
dc.contributor.authorSchneider, Glenn
dc.contributor.authorMazoyer, Johan
dc.contributor.authorKolokolova, Ludmilla
dc.date.accessioned2018-08-16T21:19:18Z
dc.date.available2018-08-16T21:19:18Z
dc.date.issued2018-06-20
dc.identifier.citationCharles A. Poteet et al 2018 ApJ 860 115en_US
dc.identifier.issn1538-4357
dc.identifier.doi10.3847/1538-4357/aac2e4
dc.identifier.urihttp://hdl.handle.net/10150/628572
dc.description.abstractWe present Hubble Space Telescope Near-Infrared Camera and Multi-Object Spectrometer coronagraphic imaging polarimetry of the TW Hydrae protoplanetary disk. These observations simultaneously measure the total and polarized intensity, allowing direct measurement of the polarization fraction across the disk. In accord with the self-shadowing hypothesis recently proposed by Debes et al., we find that the total and polarized intensity of the disk exhibits strong azimuthal asymmetries at projected distances consistent with the previously reported bright and dark ring-shaped structures (similar to 45-99 au). The sinusoidal-like variations possess a maximum brightness at position angles near similar to 268 degrees-300 degrees and are up to similar to 28% stronger in total intensity. Furthermore, significant radial and azimuthal variations are also detected in the polarization fraction of the disk. In particular, we find that regions of lower polarization fraction are associated with annuli of increased surface brightness, suggesting that the relative proportion of multiple-to-single scattering is greater along the ring and gap structures. Moreover, we find strong (similar to 20%) azimuthal variation in the polarization fraction along the shadowed region of the disk. Further investigation reveals that the azimuthal variation is not the result of disk flaring effects, but is instead from a decrease in the relative contribution of multiple-to-single scattering within the shadowed region. Employing a two-layer scattering surface, we hypothesize that the diminished contribution in multiple scattering may result from shadowing by an inclined inner disk, which prevents direct stellar light from reaching the optically thick underlying surface component.en_US
dc.description.sponsorshipNASA from the Space Telescope Science Institute [HST-AR-12630]; Association of Universities for Research in Astronomy, Incorporated, under NASA [NAS 5-26555]en_US
dc.language.isoenen_US
dc.publisherIOP PUBLISHING LTDen_US
dc.relation.urlhttp://stacks.iop.org/0004-637X/860/i=2/a=115?key=crossref.e15f98d2a34644dbbb4fca9470f0a407en_US
dc.rights© 2018. The American Astronomical Society. All rights reserved.en_US
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.subjectcircumstellar matteren_US
dc.subjectpolarizationen_US
dc.subjectprotoplanetary disksen_US
dc.subjectstars: individual (TW Hya)en_US
dc.subjectstars: pre-main sequenceen_US
dc.titleSpace-based Coronagraphic Imaging Polarimetry of the TW Hydrae Disk: Shedding New Light on Self-shadowing Effectsen_US
dc.typeArticleen_US
dc.contributor.departmentUniv Arizona, Steward Observen_US
dc.identifier.journalASTROPHYSICAL JOURNALen_US
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en_US
dc.eprint.versionFinal published versionen_US
dc.source.journaltitleThe Astrophysical Journal
dc.source.volume860
dc.source.issue2
dc.source.beginpage115
refterms.dateFOA2018-08-16T21:19:18Z


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