Multiband Polarimetric Imaging of HR 4796A with the Gemini Planet Imager
Abstract
HR4796A hosts a well-studied debris disk with a long history due to its high fractional luminosity and favorable inclination lending itself well to both unresolved and resolved observations. We present new J- and K1-band images of the resolved debris disk HR4796A taken in the polarimetric mode of the Gemini Planet Imager (GPI). The polarized intensity features a strongly forward scattered brightness distribution and is undetected at the far side of the disk. The total intensity is detected at all scattering angles and also exhibits a strong forward scattering peak. We use a forward modelled geometric disk in order to extract geometric parameters, polarized fraction and total intensity scattering phase functions for these data as well as H-band data previously taken by GPI. We find the polarized phase function becomes increasingly more forward scattering as wavelength increases. We fit Mie and distribution of hollow spheres grain (DHS) models to the extracted functions. We find that while it is possible to describe generate a satisfactory model for the total intensity using a DHS model, but not with a Mie model. We find that no single grain population of DHS or Mie grains of arbitrary composition can simultaneously reproduce the polarized fraction and total intensity scattering phase functions, indicating the need for more sophisticated grain models.
Keywords
Cite
@article{arxiv.2006.06818,
title = {Multiband Polarimetric Imaging of HR 4796A with the Gemini Planet Imager},
author = {Pauline Arriaga and Michael P. Fitzgerald and Gaspard Duchêne and Paul Kalas and Maxwell A. Millar-Blanchaer and Marshall D. Perrin and Christine H. Chen and Johan Mazoyer and Mark Ammons and Vanessa P. Bailey and Trafis S. Barman and Joanna Bulger and Jeffrey K. Chilcote and Tara Cotten and Robert J. De Rosa and Rene Doyon and Thomas M. Esposito and Katherine B. Follette and Benjamin L. Gerard and Stephen Goodsell and James R. Graham and Alexandra Z. Greenbaum and Pascale Hibon and Justin Hom and Li-Wei Hung and Patrick Ingraham and Quinn M. Konopacky and Bruce A. Macintosh and Jérôme Maire and Franck Marchis and Mark S. Marley and Christian Marois and Stanimir Metchev and Eric L. Nielsen and Rebecca Oppenheimer and David W. Palmer and Jenny Patience and Lisa A. Poyneer and Laurent Pueyo and Abhijith Rajan and Julien Rameau and Fredrik T. Rantakyrö and Jean-Baptiste Ruffio and Dmitry Savransky and Adam C. Schneider and Anand Sivaramakrishnan and Inseok Song and Remi Soummer and Sandrine Thomas and Jason J. Wang and Kimberly Ward-Duong and Schuyler G. Wolff},
journal= {arXiv preprint arXiv:2006.06818},
year = {2020}
}
Comments
Accepted for publication in AJ. 3 tables, 11 figures