2017/10/31 by Catherine Walsh, Cail Daley, Stefano Facchini +2 · 3 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Flow (mathematics) #Galaxies: Formation, Evolution, Phenomena #Kinematics #Line (geometry) #Planet #Position (finance) #Position angle #Protoplanetary disk #Radial velocity #Spectral resolution #Stellar, planetary, and galactic studies #Submillimeter Array #astro-ph.EP #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.1051/0004-6361/201731334
published as 2017, A&A, 607, A114 · 16 pages, 15 figures, accepted for publication in A&A (28th September 2017), arXiv version amended to match proofs and DOI/journal reference added
openalex created_date 2017/10/20 · openalex publication_date 2017/11/01 · arxiv created 2017/12/06 · arxiv updated 2017/12/07 · openalex updated_date 2026/08/05
We present spatially resolved Atacama Large Millimeter/submillimeter Array (ALMA) images of 12CO J = 3−2 emission from the protoplanetary disk around the Herbig Ae star, HD 100546. We expand upon earlier analyses of this data and model the spatially-resolved kinematic structure of the CO emission. Assuming a velocity profile which prescribes a flat or flared emitting surface in Keplerian rotation, we uncover significant residuals with a peak of ≈7δv, where δv = 0.21 km s-1 is the width of a single spectral resolution element. The shape and extent of the residuals reveal the possible presence of a severely warped and twisted inner disk extending to at most 100 au. Adapting the model to include a misaligned inner gas disk with (i) an inclination almost edge-on to the line of sight, and (ii) a position angle almost orthogonal to that of the outer disk reduces the residuals to <3δv. However, these findings are contrasted by recent VLT/SPHERE, MagAO/GPI, and VLTI/PIONIER observations of HD 100546 that show no evidence of a severely misaligned inner dust disk down to spatial scales of ~ 1 au. An alternative explanation for the observed kinematics are fast radial flows mediated by (proto)planets. Inclusion of a radial velocity component at close to free-fall speeds and inwards of ≈50 au results in residuals of ≈4δv. Hence, the model including a radial velocity component only does not reproduce the data as well as that including a twisted and misaligned inner gas disk. Molecular emission data at a higher spatial resolution (of order 10 au) are required to further constrain the kinematics within ≲100 au. HD 100546 joins several other protoplanetary disks for which high spectral resolution molecular emission shows that the gas velocity structure cannot be described by a purely Keplerian velocity profile with a universal inclination and position angle. Regardless of the process, the most likely cause is the presence of an unseen planetary companion.