A Keplerian disk with a four

Sep 11, 2023

Nature Astronomy volume 7, pages 557–568 (2023)Cite this article

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High-mass protostars (M⋆ > 8M⊙) are thought to gain the majority of their mass via short, intense bursts of growth. This episodic accretion is thought to be facilitated by gravitationally unstable and subsequently inhomogeneous accretion disks. Limitations of observational capabilities, paired with a lack of observed accretion burst events, have withheld affirmative confirmation of the association between disk accretion, instability and the accretion burst phenomenon in high-mass protostars. Following its 2019 accretion burst, a heatwave driven by a burst of radiation propagated outward from the high-mass protostar G358.93-0.03-MM1. Six very long baseline interferometry observations of the radiatively pumped 6.7 GHz methanol maser were conducted during this period, tracing ever increasing disk radii as the heatwave propagated outward. Concatenating the very long baseline interferometry maps provided a sparsely sampled, milliarcsecond view of the spatio-kinematics of the accretion disk covering a physical range of ~50–900 AU. We term this observational approach ‘heatwave mapping’. We report the discovery of a Keplerian accretion disk with a spatially resolved four-arm spiral pattern around G358.93-0.03-MM1. This result positively implicates disk accretion and spiral arm instabilities into the episodic accretion high-mass star formation paradigm.

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Data used in this work can be accessed by searching experiment codes (Table 1) in the following data archives: LBA data (https://atoa.atnf.csiro.au), EVN data (http://archive.jive.nl/scripts/portal.php) and VLBA data (https://data.nrao.edu/portal/#/). The maser spotmaps used in this work, in addition to calibrated data from the six epochs in FITS format, are available at the following link: https://www.masermonitoring.com/g358-mm1-data-availability.

The correlate2d algorithm is available from Python's SciPy package (version 1.10.0). The MCMC algorithm is available from Python's emcee package (version 3.1.3). The RANSAC algorithm is available from the Python's scikit-learn package (version 0.19.2).

A Correction to this paper has been published: https://doi.org/10.1038/s41550-023-01944-8

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R.A.B. acknowledges support through the EACOA Fellowship from the East Asian Core Observatories Association. R.A.B., J.O.C. and G.C.M. acknowledge the Global Emerging Radio Astronomy Foundation for contributions to radio astronomy. T.H. is financially supported by the MEXT/JSPS KAKENHI Grant nos. 17K05398, 18H05222 and 20H05845. Y.Y. is financially supported by the MEXT/JSPS KAKANHI Grant nos. 21H01120 and 21H00032. L.U. acknowledges support from the University of Guanajuato (Mexico) Grant ID CIIC 164/2022. A.C.o.G. acknowledges support by PRIN-INAF-MAIN-STREAM 2017. M.O. thanks the Ministry of Education and Science of the Republic of Poland for support and granting funds for the Polish contribution to the International LOFAR Telescope (arrangement no. 2021/WK/02) and for maintenance of the LOFAR PL-612 Baldy (MSHE decision no. 28/530020/SPUB/SP/2022). A.B. and M.D. acknowledge support from the National Science Centre, Poland through Grant 2021/43/B/ST9/02008. O.B. acknowledges financial support from the Italian Ministry of University and Research – Project Proposal CIR01_00010. A.M.S. and D.A.L. were supported by the Ministry of Science and Higher Education of the Russian Federation (state contract FEUZ-2023-0019). D.J. is supported by NRC Canada and by an NSERC Discovery Grant.

Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, Mitaka, Japan

R. A. Burns & T. Hirota

Department of Science, National Astronomical Observatory of Japan, Mitaka, Japan

R. A. Burns

Korea Astronomy and Space Science Institute, Daejeon, Republic of Korea

R. A. Burns, N. Sakai & Kee-Tae Kim

Department of Physics, National Chung Hsing University, Taichung, Taiwan

Y. Uno

National Astronomical Research Institute of Thailand (Public Organization), Chiangmai, Thailand

N. Sakai & K. Sugiyama

NRAO, Socorro, NM, USA

J. Blanchard

Department of Physics, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia

Z. Rosli

Joint Institute for VLBI ERIC, Dwingeloo, the Netherlands

G. Orosz

Center for Astronomy, Ibaraki University, Mito, Japan

Y. Yonekura & Y. Tanabe

Department of Astronomical Sciences, SOKENDAI (The Graduate University for Advanced Studies), Mitaka, Japan

T. Hirota

University of Science and Technology, Daejeon, Republic of Korea

Kee-Tae Kim

Ventspils International Radio Astronomy Center, Ventspils University of Applied Sciences, Ventspils, Latvia

A. Aberfelds

Radio Astronomy and Geodynamics Department of Crimean Astrophysical Observatory, Katsiveli, Ukraine

A. E. Volvach

Institute of Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun, Poland

A. Bartkiewicz & M. Durjasz

INAF Osservatorio Astronomico di Capodimonte Napoli, Naples, Italy

A. Caratti o Garatti

Astronomical Observatory, Ural Federal University, Ekaterinburg, Russia

A. M. Sobolev & D. A. Ladeyschikov

Thüringer Landessternwarte, Tautenburg, Germany

B. Stecklum & J. Eislöffel

NRAO, Charlottesville, VA, USA

C. Brogan & T. R. Hunter

Australia Telescope National Facility, CSIRO, Epping, New South Wales, Australia

C. Phillips

NRC Herzberg Astronomy and Astrophysics, Victoria, British Columbia, Canada

D. Johnstone

INAF Osservatorio Astronomico di Cagliari, Selargius, Italy

G. Surcis

Department of Physical Sciences, The Open University of Tanzania, Dar-Es-Salaam, Tanzania

G. C. MacLeod

Hartebeesthoek Radio Astronomy Observatory, Krugersdorp, South Africa

G. C. MacLeod & S. P. van den Heever

Max Planck Institute for Astronomy, Heidelberg, Germany

H. Linz

Space Research Unit, Physics Department, North West University, Potchefstroom, South Africa

J. O. Chibueze

Department of Physics and Astronomy, Faculty of Physical Sciences, University of Nigeria, Nsukka, Nigeria

J. O. Chibueze

INAF - Istituto di Radioastronomia and Italian ALMA Regional Centre, Bologna, Italy

J. Brand

School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia

L. Hyland & S. P. Ellingsen

Departamento de Astronomía, Universidad de Guanajuato, Guanajuato, Mexico

L. Uscanga

Space Radio-Diagnostic Research Center, Faculty of Geoengineering, University of Warmia and Mazury Oczapowskiego 2, Olsztyn, Poland

M. Olech

INAF - Osservatorio Astrofisico di Arcetri, Florence, Italy

O. Bayandina

SKA Observatory, Jodrell Bank, Macclesfield, UK

S. Breen

Center for Astrophysics, Guangzhou University, Guangzhou, China

X. Chen

Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai, China

X. Chen

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R.A.B. led the project as principal investigator for the observations, processed the VLBI data and authored the paper. Y.U. performed the Keplerian modelling of the maser data. N.S. performed the spiral arm identification procedures using RANSAC and MCMC. J. Blanchard conducted the two-dimensional cross-correlation for identification of additional spiral arms. Z.R. conducted the disk inclination measurement. K.S. and Y.Y. selected the target maser source. A.E.V., J. Brand, S.P.v.d.H., Y.Y., Y.T., A.A., G.C.M., M.O. and M.D. conducted single-dish monitoring of masers towards G358.93-0.03. G.O., S.P.E., L.H. and C.P. conducted the LBA observations. All authors contributed to the scientific discussion and helped with the authorship and reviewing process of the paper.

Correspondence to R. A. Burns.

The authors declare no competing interests.

Nature Astronomy thanks the anonymous reviewers for their contribution to the peer review of this work.

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Burns, R.A., Uno, Y., Sakai, N. et al. A Keplerian disk with a four-arm spiral birthing an episodically accreting high-mass protostar. Nat Astron 7, 557–568 (2023). https://doi.org/10.1038/s41550-023-01899-w

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Received: 16 September 2022

Accepted: 18 January 2023

Published: 27 February 2023

Issue Date: May 2023

DOI: https://doi.org/10.1038/s41550-023-01899-w

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