A heatwave of accretion energy traced by masers in the G358-MM1 high-mass protostar
Journal
Date Issued
2020
Author(s)
Burns, R. A.
•
Sugiyama, K.
•
Hirota, T.
•
Kim, Kee-Tae
•
Sobolev, A. M.
•
Stecklum, B.
•
MacLeod, G. C.
•
Yonekura, Y.
•
Olech, M.
•
Orosz, G.
•
Ellingsen, S. P.
•
Hyland, L.
•
•
Brogan, C.
•
Hunter, T. R.
•
Phillips, C.
•
van den Heever, S. P.
•
Eislöffel, J.
•
Linz, H.
•
•
Chibueze, J. O.
•
Baan, W.
•
Kramer, B.
Abstract
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.
Volume
4
Start page
506
Issn Identifier
2397-3366
Ads BibCode
2020NatAs...4..506B
Rights
open.access
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