Mapping the merging zone of late infall in the AB Aur planet-forming system

Abstract

Late infall events challenge the traditional view that planet formation occurs without external influence. Here we present deep ALMA ${}^{12}$CO $J=2-1$ and SO $J_N=5_6-4_5$ observations toward AB Aurigae, a Class II disk system with strong signs of gravitational instability and ongoing planet formation. By applying Keplerian and anti-Keplerian masks, we separate disk-like and non-disk-like motions of ${}^{12}$CO, considering the two outputs as the 'disk' and 'exo-disk' (out of disk) emission components, respectively. The disk component of ${}^{12}$CO extends to $\sim 1600$ au in radius and exhibits a stunningly rich architecture of global spiral structure. The exo-disk emission consists predominantly of three spiral structures -- S1, S2 and S3 -- whose projections are co-spatial with the disk. We successfully reproduce their trajectories with a ballistic accretion flow model, finding that S1 and S2 (both redshifted) are infalling toward the disk from in front, and S3 (blueshifted) is infalling from behind. Where the terminal ends of S1 and S2 become indistinguishable from the disk, we observe a brightness peak in SO emission $2.5\times$ the azimuthal average of a background SO ring. This merging zone lies within a relatively confined region $15-100$ degrees east of north, and between $\sim 150-300$ au from the star, at scales relevant to where planet candidates have been previously identified. The AB Aur system provides a unified picture of late infall inducing replenishment of the disk, triggering gravitational instability, and modifying the conditions of forming planets.

ApJL, in press. 10 figures, 20 pages. Observational data products available at https://doi.org/10.11570/24.0098. Animations available at https://doi.org/10.6084/m9.figshare.28205066

References in corpus (41)

• Array Programming with NumPy
• Gaia Data Release 3: Summary of the content and survey properties
• Multi-Scale CLEAN deconvolution of radio synthesis images
• CMasher: Scientific colormaps for making accessible, informative and 'cmashing' plots
• PHANGS-ALMA Data Processing and Pipeline
• A protostellar system fed by a streamer of 10,500 au length
• Images of Embedded Jovian Planet Formation At A Wide Separation Around AB Aurigae
• Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): Late infall causing disk misalignment and dynamic structures in SU Aur
• ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT) VI: Accretion shocks in the disk of DG Tau and HL Tau
• Episodic accretion: the interplay of infall and disc instabilities
• PRODIGE -- Envelope to disk with NOEMA I. A 3000 au streamer feeding a Class I protostar
• Anisotropic Infall and Substructure formation in Embedded Disks
• Cloudlet capture by Transitional Disk and FU Orionis stars
• Possible evidence of ongoing planet formation in AB Aurigae. A showcase of the SPHERE/ALMA synergy
• Misaligned disks induced by infall
• Spiral Arms and a Massive Dust Disk with non-Keplerian Kinematics: Possible Evidence for Gravitational Instability in the Disk of Elias 2-27
• Vertical Structure of the Transition Zone from Infalling Rotating Envelope to Disk in the Class 0 Protostar, IRAS04368+2557
• Far-infrared to millimeter data of protoplanetary disks: dust growth in the Taurus, Ophiuchus, and Chamaeleon I star-forming regions
• Are protoplanetary disks born with vortices? -- Rossby wave instability driven by protostellar infall
• A dynamical measurement of the disk mass in Elias 2-27
• A Census of the Taurus Star-forming Region and Neighboring Associations with Gaia
• Modeling accretion shocks at the disk-envelope interface -- Sulfur chemistry
• How to Detect the Signatures of Self-Gravitating Circumstellar Discs with the Atacama Large Millimetre/sub-millimetre Array
• Dynamical mass measurements of two protoplanetary discs
• Gravitational instability in a planet-forming disk
• Reflections on nebulae around young stars: A systematic search for late-stage infall of material onto Class II disks
• Accretion Flows or Outflow Cavities? Uncovering the Gas Dynamics around Lupus 3-MMS
• HST/WFC3 H$\alpha$ Direct-Imaging Detection of a Point-like Source in the Disk Cavity of AB Aur
• Rotation curves in protoplanetary disks with thermal stratification
• Spiral-driven accretion in protoplanetary discs - III tri-dimensional simulations
• The temporal requirements of directly observing self-gravitating spiral waves in protoplanetary discs with ALMA
• Evaporation of grain-surface species by shock waves in proto-planetary disk
• Flow of gas detected from beyond the filaments to protostellar scales in Barnard 5
• Investigating Protoplanetary Disk Cooling through Kinematics: Analytical GI Wiggle
• Crescent-Shaped Molecular Outflow from the Intermediate-mass Protostar DK Cha Revealed by ALMA
• On the equations of warped disc dynamics
• Constraints on the (re-)orientation of star-disk systems through infall
• SO as shock tracer in protoplanetary disks: the AB Aurigae case
• High-resolution Pan-STARRS and SMA observations of IRAS 23077+6707: A giant edge-on protoplanetary disk
• Synthetic Observations of the Infalling Rotating Envelope: Links between the Physical Structure and Observational Features
• Constraints on the gas-phase C/O ratio of DR Tau's outer disk from CS, SO, and C${}_2$H observations

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