Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Shadows cast on the transition disk of HD 135344B. Multiwavelength
  VLT/SPHERE polarimetric differential imaging   The protoplanetary disk around the F-type star HD 135344B (SAO 206462) is in
a transition stage and shows many intriguing structures both in scattered light
and thermal (sub-)millimeter emission which are possibly related to planet
formation processes. We study the morphology and surface brightness of the disk
in scattered light to gain insight into the innermost disk regions, the
formation of protoplanets, planet-disk interactions traced in the surface and
midplane layers, and the dust grain properties of the disk surface. We have
carried out high-contrast polarimetric differential imaging (PDI) observations
with VLT/SPHERE and obtained polarized scattered light images with ZIMPOL in R-
and I-band and with IRDIS in Y- and J-band. The scattered light images reveal
with unprecedented angular resolution and sensitivity the spiral arms as well
as the 25 au cavity of the disk. Multiple shadow features are discovered on the
outer disk with one shadow only being present during the second observation
epoch. A positive surface brightness gradient is observed in the stellar
irradiation corrected images in southwest direction possibly due to an
azimuthally asymmetric perturbation of the temperature and/or surface density
by the passing spiral arms. The disk integrated polarized flux, normalized to
the stellar flux, shows a positive trend towards longer wavelengths which we
attribute to large aggregate dust grains in the disk surface. Part of the the
non-azimuthal polarization signal in the Uphi image of the J-band observation
could be the result of multiple scattering in the disk. The detected shadow
features and their possible variability have the potential to provide insight
into the structure of and processes occurring in the innermost disk regions.

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The categories of this paper are: hep-lat
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The categories of this paper are: chem-ph
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The categories of this paper are: cs
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The categories of this paper are: supr-con
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The categories of this paper are: econ
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The categories of this paper are: cmp-lg
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The categories of this paper are: chao-dyn
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The categories of this paper are: adap-org
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: solv-int
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: ao-sci