Multiwavelength analysis of polarized light in HD 100453^★

¹ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
² Institute for Particle Physics and Astrophysics, ETH Zurich, Wolfgang Pauli Strasse 17, 8093 Zurich, Switzerland
³ Department of Earth Science and Astronomy, The University of Tokyo, Tokyo 153-8902, Japan
⁴ Astronomy Department, University of California Berkeley, Berkeley, CA 94720-3411, USA
⁵ Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098XH Amsterdam, The Netherlands
⁶ School of Natural Sciences, Center for Astronomy, University of Galway, Galway H91 CF50, Ireland

^★★ Corresponding author: jie.ma@univ-grenoble-alpes.fr

Received: 30 June 2025
Accepted: 12 August 2025

Abstract

Context. HD 100453 disk is a prototypical companion-disk interaction system hosting a pair of spirals and a substellar companion.

Aims. We present new noncoronagraphic high-contrast imaging observations of HD 100453 with V filter on SPHERE/ZIMPOL. We aim to accurately measure the reflected polarized intensity, the disk intensity, and the degree of polarization at multiwavelength; characterize the dust properties in the disk ring and the companion-driven spiral arms; and search for the radial dependencies of dust scattering properties within the disk.

Methods. We combined high-contrast imaging data of the reflected light from 0.55 to 2.2 μm using the V, I′, J, and Ks band data of ZIMPOL and IRDIS at VLT/SPHERE. For each observational epoch, we corrected for the smearing effect to derive the intrinsic disk-integrated polarized flux. We applied reference differential imaging to extract the disk intensity for the V and Ks bands using star hopping observations. We then used RADMC-3D radiative transfer modeling with a parametrized Henyey–Greenstein phase function to constrain the dust properties.

Results. For the integrated intrinsic polarized flux of the disk, we derived a steady increase with wavelengths from Q_φ/I_★(V) = 0.3% to Q_φ/I_★(K) = 1.2%. We obtained the first V-band total intensity for HD 100453 with ZIMPOL star hopping. The integrated total flux I_disk/I_★(V) = 1.5% increases to I_disk/I_★(K) = 4.8%. Both the total intensity and the polarization fraction show red colors, and the intrinsic maximum degree of polarization increases moderately from 40% to 55%. From the V to Ks band, the dominating dust in the outer disk has an increasing scattering albedo and degree of polarization, while the asymmetry parameter slightly decreases. The outer disk of HD 100453 contains sub-micron-sized low porosity grains/aggregates. The cavity in scattered light is not empty and is replenished with optically thin dust with a maximum size of ≤ 0.1 μm. The linear polarization is higher in the spiral region than in the other regions, suggesting different dust properties in those regions.