A heatwave of accretion energy traced by masers in the G358-MM1 high-mass protostar

R. A. Burns, K. Sugiyama, T. Hirota, Kee Tae Kim, A. M. Sobolev, B. Stecklum, G. C. MacLeod, Y. Yonekura, M. Olech, G. Orosz, S. P. Ellingsen, L. Hyland, A. Caratti o Garatti, C. Brogan, T. R. Hunter, C. Phillips, S. P. van den Heever, J. Eislöffel, H. Linz, G. SurcisJ. O. Chibueze, W. Baan, B. Kramer

Research output: Contribution to journalArticlepeer-review

59 Citations (Scopus)


High-mass stars are thought to accumulate much of their mass via short, infrequent bursts of disk-aided accretion1,2. Such accretion events are rare and difficult to observe directly but are known to drive enhanced maser emission3–6. In this Letter we report high-resolution, multi-epoch methanol maser observations toward G358.93-0.03, which reveal an interesting phenomenon: the subluminal propagation of a thermal radiation ‘heatwave’ emanating from an accreting high-mass protostar. The extreme transformation of the maser emission implies a sudden intensification of thermal infrared radiation from within the inner (40-mas, 270-au) region. Subsequently, methanol masers trace the radial passage of thermal radiation through the environment at ≥4% of the speed of light. Such a high translocation rate contrasts with the ≤10 km s−1 physical gas motions of methanol masers typically observed using very-long-baseline interferometry (VLBI). The observed scenario can readily be attributed to an accretion event in the high-mass protostar G358.93-0.03-MM1. While being the third case in its class, G358.93-0.03-MM1 exhibits unique attributes hinting at a possible ‘zoo’ of accretion burst types. These results promote the advantages of maser observations in understanding high-mass-star formation, both through single-dish maser monitoring campaigns and via their international cooperation as VLBI arrays.

Original languageEnglish
Pages (from-to)506-510
Number of pages5
JournalNature Astronomy
Issue number5
Publication statusPublished - 1 May 2020
Externally publishedYes


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