GPI Spectra of HR 8799 c, d, and e from 1.5 to 2.4 μm with KLIP Forward Modeling

June 2018 • 2018AJ....155..226G

Authors • Greenbaum, Alexandra Z. • Pueyo, Laurent • Ruffio, Jean-Baptiste • Wang, Jason J. • De Rosa, Robert J. • Aguilar, Jonathan • Rameau, Julien • Barman, Travis • Marois, Christian • Marley, Mark S. • Konopacky, Quinn • Rajan, Abhijith • Macintosh, Bruce • Ansdell, Megan • Arriaga, Pauline • Bailey, Vanessa P. • Bulger, Joanna • Burrows, Adam S. • Chilcote, Jeffrey • Cotten, Tara • Doyon, Rene • Duchêne, Gaspard • Fitzgerald, Michael P. • Follette, Katherine B. • Gerard, Benjamin • Goodsell, Stephen J. • Graham, James R. • Hibon, Pascale • Hung, Li-Wei • Ingraham, Patrick • Kalas, Paul • Larkin, James E. • Maire, Jérôme • Marchis, Franck • Metchev, Stanimir • Millar-Blanchaer, Maxwell A. • Nielsen, Eric L. • Norton, Andrew • Oppenheimer, Rebecca • Palmer, David • Patience, Jennifer • Perrin, Marshall D. • Poyneer, Lisa • Rantakyrö, Fredrik T. • Savransky, Dmitry • Schneider, Adam C. • Sivaramakrishnan, Anand • Song, Inseok • Soummer, Rémi • Thomas, Sandrine • Wallace, J. Kent • Ward-Duong, Kimberly • Wiktorowicz, Sloane • Wolff, Schuyler

Abstract • We explore KLIP forward modeling spectral extraction on Gemini Planet Imager coronagraphic data of HR 8799, using PyKLIP, and show algorithm stability with varying KLIP parameters. We report new and re-reduced spectrophotometry of HR 8799 c, d, and e in the H and K bands. We discuss a strategy for choosing optimal KLIP PSF subtraction parameters by injecting simulated sources and recovering them over a range of parameters. The K1/K2 spectra for HR 8799 c and d are similar to previously published results from the same data set. We also present a K-band spectrum of HR 8799 e for the first time and show that our H-band spectra agree well with previously published spectra from the VLT/SPHERE instrument. We show that HR 8799 c and d show significant differences in their H and K spectra, but do not find any conclusive differences between d and e, nor between c and e, likely due to large error bars in the recovered spectrum of e. Compared to M-, L-, and T-type field brown dwarfs, all three planets are most consistent with mid- and late-L spectral types. All objects are consistent with low gravity, but a lack of standard spectra for low gravity limit the ability to fit the best spectral type. We discuss how dedicated modeling efforts can better fit HR 8799 planets’ near-IR flux, as well as how differences between the properties of these planets can be further explored.

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Alexandra Greenbaum

Assistant Scientist