Disk Kinematics and Stability in High-Mass Star Formation: Linking Simulations and Observations

Abstract

In the disk-mediated accretion scenario for the formation of the most massive stars, gravitational instabilities in the disk can force it to fragment. We investigate the effects of inclination and spatial resolution on observable kinematics and stability of disks in high-mass star formation. We study a high-resolution 3D radiation-hydrodynamic simulation that leads to the fragmentation of a massive disk. Using RADMC-3D we produce 1.3 mm continuum and CH3CN line cubes at different inclinations. The model is set to different distances and synthetic observations are created for ALMA at ~80 mas resolution and NOEMA at ~0.3''. The synthetic ALMA observations resolve all fragments and their kinematics well. The synthetic NOEMA observations at 800 pc (~300 au resolution) are able to resolve the fragments, while at 2000 pc (~800 au resolution) only a single slightly elongated structure is observed. The position-velocity (PV) plots show the differential rotation of material best in the edge-on views. As the observations become less resolved, the inner high-velocity components of the disk become blended with the envelope and the PV plots resemble rigid-body-like rotation. Protostellar mass estimates from PV plots of poorly resolved observations are therefore overestimated. We fit the emission of CH3CN lines and produce maps of gas temperature with values in the range of 100-300 K. Studying the Toomre stability of the disks in the resolved observations, we find Q values below the critical value for stability against gravitational collapse at the positions of the fragments and the arms connecting the fragments. For the poorly resolved observations we find low Q values in the outskirts of the disk. Therefore we are able to predict that the disk is unstable and fragmenting even in poorly resolved observations. This conclusion is true regardless of knowledge about the inclination of the disk.

21 pages, 15 figures, accepted for publication in Astronomy and Astrophysics - corrected captions of Fig. 13 & 15

References in corpus (16)

• PLUTO: a Numerical Code for Computational Astrophysics
• Circumventing the radiation pressure barrier in the formation of massive stars via disk accretion
• Three-dimensional simulation of massive star formation in the disk accretion scenario
• Fragmentation of Massive Protostellar Disks
• On the existence of accretion-driven bursts in massive star formation
• An Unstable Truth: How Massive Stars get their Mass
• G11.92-0.61 MM1: A Keplerian disc around a massive young proto-O star
• Forming spectroscopic massive proto-binaries by disk fragmentation
• Molecular Line Emission from Massive Protostellar Disks: Predictions for ALMA and the EVLA
• Protostellar Outflows and Radiative Feedback from Massive Stars. II. Feedback, Star Formation Efficiency, and Outflow Broadening
• Substructures in the Keplerian disc around the O-type (proto)star G17.64+0.16
• Protostellar Outflows and Radiative Feedback from Massive Stars
• Molecular outflow launched beyond the disk edge
• Radiation-hydrodynamical simulations of massive star formation using Monte Carlo radiative transfer II. The formation of a 25 solar-mass star
• An Asymmetric Keplerian Disk Surrounding the O-type Protostar IRAS16547$-$4247
• ALMA reveals a candidate hot and compact disk around the O-type protostar IRAS 16547$-$4247

Cited by in corpus (5)

• Spiral arms and instability within the AFGL 4176 mm1 disc
• Digging into the Interior of Hot Cores with ALMA (DIHCA). I. Dissecting the High-mass Star-Forming Core G335.579-0.292 MM1
• Parameter study for the burst mode of accretion in massive star formation
• Makemake + Sedna: A Continuum Radiation Transport and Photoionization Framework for Astrophysical Newtonian Fluid Dynamics
• The physical and chemical structure of high-mass star-forming regions. Unraveling chemical complexity with the NOEMA large program "CORE"