$β$ Pictoris' inner disk in polarized light and new orbital parameters for $β$ Pictoris b
Creators: name: Millar-Blanchaer, Maxwell A.
name: Graham, James R.
name: Pueyo, Laurent
name: Kalas, Paul
name: Dawson, Rebekah I.
name: Wang, Jason
name: Perrin, Marshall
name: Moon, Dae-Sik
name: Macintosh, Bruce
name: Ammons, S. Mark
name: Barman, Travis
name: Cardwell, Andrew
name: Chen, Christine H.
name: Chiang, Eugene
name: Chilcote, Jeffrey
name: Cotten, Tara
name: De Rosa, Robert J.
name: Draper, Zachary H.
name: Dunn, Jennifer
name: Duchêne, Gaspard
name: Esposito, Thomas M.
name: Fitzgerald, Michael P.
name: Follette, Katherine B.
name: Goodsell, Stephen J.
name: Greenbaum, Alexandra Z.
name: Hartung, Markus
name: Hibon, Pascale
name: Hinkley, Sasha
name: Ingraham, Patrick
name: Jensen-Clem, Rebecca
name: Konopacky, Quinn
name: Larkin, James E.
name: Long, Douglas
name: Maire, Jérôme
name: Marchis, Franck
name: Marley, Mark S.
name: Marois, Christian
name: Morzinski, Katie M.
name: Nielsen, Eric L.
name: Palmer, David W.
name: Oppenheimer, Rebecca
name: Poyneer, Lisa
name: Rajan, Abhijith
name: Rantakyrö, Fredrik T.
name: Ruffio, Jean-Baptiste
name: Sadakuni, Naru
name: Saddlemyer, Leslie
name: Schneider, Adam C.
name: Sivaramakrishnan, Anand
name: Soummer, Remi
name: Thomas, Sandrine
name: Vasisht, Gautam
name: Vega, David
name: Wallace, J. Kent
name: Ward-Duong, Kimberly
name: Wiktorowicz, Sloane J.
name: Wolff, Schuyler G.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We present $H$-band observations of $β$ Pic with the Gemini Planet Imager's (GPI's) polarimetry mode that reveal the debris disk between ~0.3" (~6 AU) and ~1.7" (~33 AU), while simultaneously detecting $β$ Pic $b$. The polarized disk image was fit with a dust density model combined with a Henyey-Greenstein scattering phase function. The best fit model indicates a disk inclined to the line of sight ($ϕ=85.27°^{+0.26}_{-0.19}$) with a position angle $θ_{PA}=30.35°^{+0.29}_{-0.28}$ (slightly offset from the main outer disk, $θ_{PA}\approx29°$), that extends from an inner disk radius of $23.6^{+0.9}_{-0.6}$ AU to well outside GPI's field of view. In addition, we present an updated orbit for $β$ Pic $b$ based on new astrometric measurements taken in GPI's spectroscopic mode spanning 14 months. The planet has a semi-major axis of $a=9.2^{+1.5}_{-0.4}$AU, with an eccentricity $e\leq 0.26$. The position angle of the ascending node is $Ω=31.75°\pm0.15$, offset from both the outer main disk and the inner disk seen in the GPI image. The orbital fit constrains the stellar mass of $β$ Pic to $1.60\pm0.05 M_{\odot}$. Dynamical sculpting by $β$ Pic $b$ cannot easily account for the following three aspects of the inferred disk properties: 1) the modeled inner radius of the disk is farther out than expected if caused by $β$ Pic b; 2) the mutual inclination of the inner disk and $β$ Pic $b$ is $4°$, when it is expected to be closer to zero; and 3) the aspect ratio of the disk ($h_0 = 0.137^{+0.005}_{-0.006}$) is larger than expected from interactions with $β$ Pic $b$ or self-stirring by the disk's parent bodies.