An Optical/Near-infrared Investigation of HD 100546 b with the Gemini Planet Imager and MagAO

June 2017 • 2017AJ....153..244R

Authors • Rameau, Julien • Follette, Katherine B. • Pueyo, Laurent • Marois, Christian • Macintosh, Bruce • Millar-Blanchaer, Maxwell • Wang, Jason J. • Vega, David • Doyon, René • Lafrenière, David • Nielsen, Eric L. • Bailey, Vanessa • Chilcote, Jeffrey K. • Close, Laird M. • Esposito, Thomas M. • Males, Jared R. • Metchev, Stanimir • Morzinski, Katie M. • Ruffio, Jean-Baptiste • Wolff, Schuyler G. • Ammons, S. M. • Barman, Travis S. • Bulger, Joanna • Cotten, Tara • De Rosa, Robert J. • Duchene, Gaspard • Fitzgerald, Michael P. • Goodsell, Stephen • Graham, James R. • Greenbaum, Alexandra Z. • Hibon, Pascale • Hung, Li-Wei • Ingraham, Patrick • Kalas, Paul • Konopacky, Quinn • Larkin, James E. • Maire, Jérôme • Marchis, Franck • Oppenheimer, Rebecca • Palmer, David • Patience, Jennifer • Perrin, Marshall D. • Poyneer, Lisa • Rajan, Abhijith • Rantakyrö, Fredrik T. • Marley, Mark S. • Savransky, Dmitry • Schneider, Adam C. • Sivaramakrishnan, Anand • Song, Inseok • Soummer, Remi • Thomas, Sandrine • Wallace, J. Kent • Ward-Duong, Kimberly • Wiktorowicz, Sloane

Abstract • We present H band spectroscopic and Hα photometric observations of HD 100546 obtained with the Gemini Planet Imager and the Magellan Visible AO camera. We detect H band emission at the location of the protoplanet HD 100546 b, but show that the choice of data processing parameters strongly affects the morphology of this source. It appears point-like in some aggressive reductions, but rejoins an extended disk structure in the majority of the others. Furthermore, we demonstrate that this emission appears stationary on a timescale of 4.6 years, inconsistent at the 2σ level with a Keplerian clockwise orbit at 59 au in the disk plane. The H band spectrum of the emission is inconsistent with any type of low effective temperature object or accreting protoplanetary disk. It strongly suggests a scattered-light origin, as this is consistent with the spectrum of the star and the spectra extracted at other locations in the disk. A non-detection at the 5σ level of HD 100546 b in differential Hα imaging places an upper limit, assuming the protoplanet lies in a gap free of extinction, on the accretion luminosity of 1.7 × 10-4 L and M\dot{M}< 6.3× {10}-7 {M}{Jup}2 {{yr}}-1 for 1 R Jup. These limits are comparable to the accretion luminosity and accretion rate of T-Tauri stars or LkCa 15 b. Taken together, these lines of evidence suggest that the H band source at the location of HD 100546 b is not emitted by a planetary photosphere or an accreting circumplanetary disk but is a disk feature enhanced by the point-spread function subtraction process. This non-detection is consistent with the non-detection in the K band reported in an earlier study but does not exclude the possibility that HD 100546 b is deeply embedded.


IPAC Authors

Alexandra Greenbaum

Assistant Scientist