Direct Imaging of the HD 35841 Debris Disk : A Polarized Dust Ring from Gemini Planet Imager and an Outer Halo from HST/STIS

Author(s): Esposito, TM; Duchne, G; Kalas, P; Rice, M; Choquet, I; Ren, B; Perrin, MD; Chen, CH; Arriaga, P; Chiang, E; Nielsen, EL; Graham, JR; Wang, JJ; Rosa, RJD; Follette, KB; Ammons, SM; Ansdell, M; Bailey, VP; Barman, T; Bruzzone, JS; Bulger, J; Chilcote, J; Cotten, T; Doyon, R; Fitzgerald, MP; Goodsell, SJ; Greenbaum, AZ; Hibon, P; Hung, LW; Ingraham, P; Konopacky, Q; Larkin, JE; Macintosh, B; Maire, J; Marchis, F; Marois, C; Mazoyer, J; Metchev, S; Millar-Blanchaer, MA; Oppenheimer, R; Palmer, D; Patience, J; Poyneer, L; Pueyo, L; Rajan, A; Rameau, J; Rantakyro, FT; Ryan, D; Savransky, D; Schneider, AC; Sivaramakrishnan, A; Song, I; Soummer, R; Thomas, S; Wallace, JK; Ward-Duong, K; Wiktorowicz, S; Wolff, S | Abstract: © 2018. The American Astronomical Society. All rights reserved.. We present new high resolution imaging of a light-scattering dust ring and halo around the young star HD 35841. Using spectroscopic and polarimetric data from the Gemini Planet Imager in H-band (1.6 μm), we detect the highly inclined (i = 85°) ring of debris down to a projected separation of ∼12 au (∼0.″12) for the first time. Optical imaging from HST/STIS shows a smooth dust halo extending outward from the ring to g140 au (g1.″4). We measure the ring's scattering phase function and polarization fraction over scattering angles of 22°-125°, showing a preference for forward scattering and a polarization fraction that peaks at ∼30% near the ansae. Modeling of the scattered-light disk indicates that the ring spans radii of ∼60-220 au, has a vertical thickness similar to that of other resolved dust rings, and contains grains as small as 1.5 μm in diameter. These models also suggest the grains have a low porosity, are more likely to consist of carbon than astrosilicates, and contain significant water ice. The halo has a surface brightness profile consistent with that expected from grains pushed by radiation pressure from the main ring onto highly eccentric but still bound orbits. We also briefly investigate arrangements of a possible inner disk component implied by our spectral energy distribution models, and speculate about the limitations of Mie theory for doing detailed analyses of debris disk dust populations.