Radiative transfer modelling of W33A MM1: 3-D structure and dynamics of a complex massive star forming region

Abstract

We present a composite model and radiative transfer simulations of the massive star forming core W33A MM1. The model was tailored to reproduce the complex features observed with ALMA at $\approx 0.2$ arcsec resolution in CH${}_3$CN and dust emission. The MM1 core is fragmented into six compact sources coexisting within $\sim 1000$ au. In our models, three of these compact sources are better represented as disc-envelope systems around a central (proto)star, two as envelopes with a central object, and one as a pure envelope. The model of the most prominent object (Main) contains the most massive (proto)star ($M_{\star }\approx 7M_{\odot }$) and disc+envelope ($M_{\mathrm{gas}}\approx 0.4M_{\odot }$), and is the most luminous ($L_{\mathrm{Main}}\sim 10^4{L}_{\odot }$). The model discs are small (a few hundred au) for all sources. The composite model shows that the elongated spiral-like feature converging to the MM1 core can be convincingly interpreted as a filamentary accretion flow that feeds the rising stellar system. The kinematics of this filament is reproduced by a parabolic trajectory with focus at the center of mass of the region. Radial collapse and fragmentation within this filament, as well as smaller filamentary flows between pairs of sources are proposed to exist. Our modelling supports an interpretation where what was once considered as a single massive star with a $\sim 10^3$ au disc and envelope, is instead a forming stellar association which appears to be virialized and to form several low-mass stars per high-mass object.

22 pages, 13 figures, 3 tables. Accepted for publication in MNRAS

References in corpus (65)

• Astropy: A Community Python Package for Astronomy
• The NumPy array: a structure for efficient numerical computation
• Embedded Clusters in Molecular Clouds
• An atomic and molecular database for analysis of submillimetre line observations
• Toward Understanding Massive Star Formation
• Cold Dark Clouds: The Initial Conditions for Star Formation
• Physical Conditions in Regions of Star Formation
• High-Mass Star and Massive Cluster Formation in the Milky Way
• 2-D Radiative Transfer in Protostellar Envelopes: I. Effects of Geometry on Class I Sources
• The mass function of dense molecular cores and the origin of the IMF
• Massive star formation: Nurture, not nature
• Gas expulsion and the destruction of massive young clusters
• Global collapse of molecular clouds as a formation mechanism for the most massive stars
• Dynamic star formation in the massive DR21 filament
• Spiral Density Waves in a Young Protoplanetary Disk
• Structure and Evolution of the Envelopes of Deeply Embedded Massive Young Stars
• Evolution of Massive Protostars via Disk Accretion
• LIME - a flexible, non-LTE line excitation and radiation transfer method for millimeter and far-infrared wavelengths
• H II regions: Witnesses to massive star formation
• A disk of dust and molecular gas around a high-mass protostar
• The Simultaneous Formation of Massive Stars and Stellar Clusters
• An extraordinary outburst in the massive protostellar system NGC6334I-MM1: quadrupling of the millimeter continuum
• Accretion disks in luminous young stellar objects
• The formation of massive stars: accretion, disks and the development of hypercompact HII regions
• The physical and chemical structure of Sagittarius B2, I. Three-dimensional thermal dust and free-free continuum modeling on 100 au to 45 pc scales
• A distance limited sample of massive molecular outflows
• A CH3CN and HCO+ survey towards southern methanol masers associated with star formation
• A Keplerian-like disk around the forming O-type star AFGL 4176
• An Unstable Truth: How Massive Stars get their Mass
• Hierarchical Cluster Assembly in Globally Collapsing Clouds
• A candidate circumbinary Keplerian disk in G35.20-0.74 N: A study with ALMA
• The dynamics of collapsing cores and star formation
• From the Convergence of Filaments to Disk-Outflow Accretion: Massive-Star Formation in W33A
• The Origin and Universality of the Stellar Initial Mass Function
• Collapse of a molecular cloud core to stellar densities: the formation and evolution of pre-stellar discs
• The circumstellar disk, envelope, and bi-polar outflow of the Massive Young Stellar Object W33A
• ALMA resolves the spiraling accretion flow in the luminous OB cluster forming region G33.92+0.11
• Molecular Line Emission from Massive Protostellar Disks: Predictions for ALMA and the EVLA
• Observations of Solids in Protoplanetary Disks
• Evidence For Cloud-Cloud Collision and Parsec-Scale Stellar Feedback Within the L1641-N Region
• Very compact radio emission from high-mass protostars. II. Dust disks and ionized accretion flows
• Formation of an O-Star Cluster by Hierarchical Accretion in G20.08-0.14 N
• Strong effect of the cluster environment on the size of protoplanetary discs?
• Trigonometric Parallaxes of Massive Star Forming Regions: G012.88+0.48 and W33
• Resolving the polarized dust emission of the disk around the massive star powering the HH~80-81 radio jet
• Systematic analysis of spectral energy distributions and the dust opacity indices for Class 0 young stellar objects
• Thermal Feedback in the high-mass star and cluster forming region W51
• Modeling molecular hyperfine line emission
• Collapsing Hot Molecular Cores: A Model for the Dust Spectrum and Ammonia Line Emission of the G31.41+0.31 Hot Core
• The standard model of star formation applied to massive stars: accretion disks and envelopes in molecular lines
• Bondi-Hoyle-Littleton accretion and the upper mass stellar IMF
• The origin of mid-infrared emission in massive young stellar objects: multi-baseline VLTI observations of W33A
• Cloud Structure of Galactic OB Cluster Forming Regions from Combining Ground and Space Based Bolometric Observations
• Resolving the Circumstellar Disk Around the Massive Protostar Driving the HH 80-81 Jet
• The Origin of OB Clusters: From 10 pc to 0.1 pc
• The ALMA view of W33A: A Spiral Filament Feeding the Candidate Disc in MM1-Main
• Fragmenting protostellar disks: properties and observational signatures
• Diversity of chemistry and excitation conditions in the high-mass star forming complex W33
• Fragmentation and disk formation in high-mass star formation: The ALMA view of G351.77-0.54 at 0.06" resolution
• VLTI/MIDI 10 micron interferometry of the forming massive star W33A
• The multiplicity of massive stars: a 2016 view
• 1000 AU Exterior Arcs Connected to the Protoplanetary Disk around HL Tau
• On the Origin of the Salpeter Slope for the Initial Mass Function
• Modelling the 3D physical structure of astrophysical sources with GASS
• NGC 7538 IRS1: Interaction of a polarized dust spiral and a molecular outflow

Cited by in corpus (35)

• Water in star-forming regions (WISH): Physics and chemistry from clouds to disks as probed by Herschel spectroscopy
• Gravity Driven Magnetic Field at ~1000 au Scales in High-mass Star Formation
• ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- XI. From inflow to infall in hub-filament systems
• Substructures in the Keplerian disc around the O-type (proto)star G17.64+0.16
• ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- XV. Steady Accretion from Global Collapse to Core Feeding in Massive Hub-filament System SDC335
• The Disc Miner I: A statistical framework to detect and quantify kinematical perturbations driven by young planets in discs
• Chasing discs around O-type (proto)stars - ALMA evidence for an SiO disc and disc wind from G17.64+0.16
• The Physical and chemical structure of Sagittarius B2 -- IV. Converging filaments in the high-mass cluster forming region Sgr B2(N)
• On the Effects of Self-Obscuration in the (Sub-)Millimeter Spectral Indices and Appearance of Protostellar Disks
• The history of dynamics and stellar feedback revealed by the HI filamentary structure in the disk of the Milky Way
• Digging into the Interior of Hot Cores with ALMA (DIHCA). I. Dissecting the High-mass Star-Forming Core G335.579-0.292 MM1
• High-mass star formation at sub-50AU scales
• Investigating fragmentation of gas structures in OB cluster-forming molecular clump G33.92+0.11 with 1000 AU resolution observations of ALMA
• ALMA-IMF XV: The core mass function in the high-mass star-formation regime
• Digging into the Interior of Hot Cores with ALMA (DIHCA). II. Exploring the Inner Binary (Multiple) System Embedded in G335 MM1 ALMA1
• The evolution of temperature and density structures of OB cluster-forming molecular clumps
• Observing substructure in circumstellar discs around massive young stellar objects
• Protostellar Outflows at the EarliesT Stages (POETS). III. H2O masers tracing disk-winds and jets near luminous YSOs
• IRAS23385+6053: An embedded massive cluster in the making
• Zooming into the Collimation Zone in a Massive Protostellar Jet
• A Detailed View of the Circumstellar Environment and Disk of the Forming O-star AFGL 4176
• Recombination Lines and Molecular Gas from Hypercompact HII regions in W51 A
• Importance of source structure on complex organics emission III. Effect of disks around massive protostars
• The Cloud Factory II: Gravoturbulent Kinematics of Resolved Molecular Clouds in a Galactic Potential
• A giant planet shaping the disk around the very low-mass star CIDA 1
• ALMA-IMF XVIII: The assembly of a star cluster: Dense N${}_2$H${}^{+}$ (1-0) kinematics in the massive G351.77 protocluster
• Multi-line Herschel/HIFI observations of water reveal infall motions and chemical segregation around high-mass protostars
• Multi-wavelength modelling of the circumstellar environment of the massive proto-star AFGL 2591 VLA 3
• K-band High-Resolution Spectroscopy of Embedded Massive Protostars
• Tying the geometrical traits of massive young stellar objects and their discs to a potential evolutionary sequence using infrared observations
• Clustered Formation of Massive Stars within an Ionized Rotating Disk
• A high-resolution radio study of the L1551 IRS 5 and L1551 NE jets
• Digging into the Interior of Hot Cores with ALMA (DIHCA). VII. Disk candidates around high-mass stars and evidence of anisotropic infall
• ngVLA Synthetic Observations of Ionized Gas in Massive Protostars
• A Core Mass Function Indistinguishable from the Salpeter Stellar Initial Mass Function Using 1000 au Resolution ALMA Observations