Imaging the disc rim and a moving close-in companion candidate in the pre-transitional disc of V1247 Orionis

Willson, Matthew; Kraus, Stefan; Kluska, Jacques; Monnier, John D.; Cure, Michel; Sitko, Mike; Aarnio, Alicia; Ireland, Michael J.; Rizzuto, Aaron; Hone, Edward; Kreplin, Alexander; Andrews, Sean; Calvet, Nuria; Espaillat, Catherine; Fukagawa, Misato; Harries, Tim J.; Hinkley, Sasha; Kanaan, Samer; Muto, Takayuki; Wilner, David J.

Context. V1247 Orionis harbours a pre-transitional disc with a partially cleared gap. Earlier interferometric and polarimetric observations revealed strong asymmetries both in the gap region and in the outer disc. The presence of a companion was inferred to explain these asymmetric structures and the ongoing disc clearing.
Aims: Using an extensive set of multi-wavelength and multi-epoch observations we aimed to identify the origin of the previously detected asymmetries.
Methods: We have observed V1247 Ori at three epochs spanning 678 days using sparse aperture masking interferometry with Keck/NIRC2 and VLT/NACO. In addition, we search for signs of accretion through VLT/SPHERE-ZIMPOL spectral differential imaging in Hα and R-band continuum. Our SMA sub-millimetre interferometry in 880 μm continuum and in the CO(3-2) line allows us to constrain the orientation and direction of rotation of the outer disc.
Results: We find the L’-band emission to be dominated by static features which trace forward-scattered dust emission from the inner edge of the outer disc located to the north-east. In H- and K-bands, we see evidence for a companion candidate that moved systematically by 45° within the first 345 days. The separation of the companion candidate is not well constrained, but the observed position angle change is consistent with Keplerian motion of a body located on a 6 au orbit. From the SMA CO moment map, the location of the disc rim, and the detected orbital motion, we deduced the three-dimensional orientation of the disc. We see no indication of accretion in Hα and set upper limits for an accreting companion.
Conclusions: The measured contrast of the companion candidate in H and K is consistent with an actively accreting protoplanet. Hence, we identify V1247 Ori as a unique laboratory for studying companion-disc interactions and disc clearing. Based on observations made with the Keck observatory (NASA programme IDs N104N2 and N121N2), with ESO telescopes at the Paranal Observatory (ESO programme IDs 60.A-9356(A) and 090.C-0904(A)), and with the Submillimeter Array (SMA programme ID 2012B-S032).

DOI: 10.1051/0004-6361/201630215