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.
planets and satellites: gaseous planets, stars: individual (HR 8799)
© 2018. The American Astronomical Society.
Greenbaum, Alexandra Z.; Pueyo, Laurent; Ruffio, Jean Baptiste; Wang, Jason J.; Rosa, Robert J.De; 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.; Ward-Duong, Kimberly; and al, et, "GPI Spectra of HR 8799 c, d, and e from 1.5 To 2.4 μm with KLIP Forward Modeling" (2018). Astronomy: Faculty Publications, Smith College, Northampton, MA.