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Episodic accretion and mergers during growth of massive protostars

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posted on 2024-03-14, 11:29 authored by Vardan G Elbakyan, Sergei Nayakshin, Dominique M-A Meyer, Eduard I Vorobyov

3D simulations of high mass young stellar object (HMYSO) growth show that their circumstellar discs fragment on to multiple self-gravitating objects. Accretion of these by HMYSO may explain episodic accretion bursts discovered recently. We post-process results of a previous 3D simulation of a HMYSO disc with a 1D code that resolves the disc and object dynamics down to the stellar surface. We find that burst-like deposition of material into the inner disc seen in 3D simulations by itself does not always signify powerful accretion bursts. Only high density post-collapse clumps crossing the inner computational boundary may result in observable bursts. The rich physics of the inner disc has a significant impact on the expected accretion bursts: (1) in the standard turbulent viscosity discs, migrating objects can stall at a migration trap at the distance of a few au from the star. However, in discs powered by magnetized winds, the objects are able to cross the trap and produce bursts akin to those observed so far. (2) Migrating objects may interact with and modify the thermal (hydrogen ionization) instability of the inner disc, which can be responsible for longer duration and lower luminosity bursts in HMYSOs. (3) If the central star is bloated to a fraction of an au by a previous episode of high accretion rate, or if the migrating object is particularly dense, a merger rather than a disc-mediated accretion burst results; (4) Object disruption bursts may be super-Eddington, leading to episodic feedback on HMYSO surroundings via powerful outflows.

Funding

Astrophysics Research at the University of Leicester

Science and Technology Facilities Council

Find out more...

Ministry of Science and Higher Education of the Russian Federation under the grant 075-15-2020-780 (N13.1902.21.0039)

History

Author affiliation

College of Science & Engineering/Physics & Astronomy

Version

  • VoR (Version of Record)

Published in

Monthly Notices of the Royal Astronomical Society

Volume

518

Issue

1

Pagination

791 - 809

Publisher

Oxford University Press (OUP)

issn

0035-8711

eissn

1365-2966

Copyright date

2022

Available date

2024-03-14

Language

en

Deposited by

Professor Sergei Nayakshin

Deposit date

2024-03-13

Data Access Statement

The data obtained in our simulations can be made available on reasonable request to the corresponding author.

Rights Retention Statement

  • No

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