Beta Pictoris' Inner Disk in Polarized Light and New Orbital Parameters for Beta Pictoris b

September 2015 • 2015ApJ...811...18M

Authors • Millar-Blanchaer, Maxwell A. • Graham, James R. • Pueyo, Laurent • Kalas, Paul • Dawson, Rebekah I. • Wang, Jason • Perrin, Marshall D. • moon, Dae-Sik • Macintosh, Bruce • Ammons, S. Mark • Barman, Travis • Cardwell, Andrew • Chen, Christine H. • Chiang, Eugene • Chilcote, Jeffrey • Cotten, Tara • De Rosa, Robert J. • Draper, Zachary H. • Dunn, Jennifer • Duchêne, Gaspard • Esposito, Thomas M. • Fitzgerald, Michael P. • Follette, Katherine B. • Goodsell, Stephen J. • Greenbaum, Alexandra Z. • Hartung, Markus • Hibon, Pascale • Hinkley, Sasha • Ingraham, Patrick • Jensen-Clem, Rebecca • Konopacky, Quinn • Larkin, James E. • Long, Douglas • Maire, Jérôme • Marchis, Franck • Marley, Mark S. • Marois, Christian • Morzinski, Katie M. • Nielsen, Eric L. • Palmer, David W. • Oppenheimer, Rebecca • Poyneer, Lisa • Rajan, Abhijith • Rantakyrö, Fredrik T. • Ruffio, Jean-Baptiste • Sadakuni, Naru • Saddlemyer, Leslie • Schneider, Adam C. • Sivaramakrishnan, Anand • Soummer, Remi • Thomas, Sandrine • Vasisht, Gautam • Vega, David • Wallace, J. Kent • Ward-Duong, Kimberly • Wiktorowicz, Sloane J. • Wolff, Schuyler G.

Abstract • 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\buildrel{\circ}\over{.} {27}-0.19+0.26) with a position angle (PA) {θ }{PA}=30\buildrel{\circ}\over{.} {35}-0.28+0.29 (slightly offset from the main outer disk, {θ }{PA}≈ 29^\circ ), that extends from an inner disk radius of {23.6}-0.6+0.9 {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 semimajor axis of a={9.2}-0.4+1.5 {AU}, with an eccentricity e≤slant 0.26. The PA of the ascending node is {{Ω }}=31\buildrel{\circ}\over{.} 75+/- 0\buildrel{\circ}\over{.} 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+/- 0.05 {M}. 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^\circ , when it is expected to be closer to zero; and (3) the aspect ratio of the disk ({h}0={0.137}-0.006+0.005) is larger than expected from interactions with β Pic b or self-stirring by the disk’s parent bodies.


IPAC Authors

Alexandra Greenbaum

Assistant Scientist