Solar-mass stars form via disk-mediated accretion. Recent findings indicate that this process is probably episodic in the form of accretion bursts, possibly caused by disk fragmentation. Although it cannot be ruled out that high-mass young stellar objects arise from the coalescence of their low-mass brethren, the latest results suggest that they more likely form via disks. It follows that disk-mediated accretion bursts should occur. Here we report on the discovery of the first disk-mediated accretion burst from a roughly twenty-solar-mass high-mass young stellar object. Our near-infrared images show the brightening of the central source and its outflow cavities. Near-infrared spectroscopy reveals emission lines typical for accretion bursts in low-mass protostars, but orders of magnitude more luminous. Moreover, the released energy and the inferred mass-accretion rate are also orders of magnitude larger. Our results identify disk-accretion as the common mechanism of star formation across the entire stellar mass spectrum. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

A.C.o.G., R.G.L. and T.P.R. were supported by Science Foundation Ireland, grant 13/ERC/I2907. A.S. was supported by the Deutsche Forschungsgemeinschaft (DFG) Priority Program 1573. We thank the ESO Paranal and Gemini Observatory staff for their support. B.S. thanks Sylvio Klose for helpful discussions concerning the light echo. This research is partly based on observations collected at the VLT (ESO Paranal, Chile) with programme 296.C-5037(A) and at the Gemini Observatory (Program ID GN-2016A-DD-5). Gemini Observatory is operated by the Association of Universities for Research in Astronomy, under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil).

Caratti o Garatti, A. et al.-- Full list of authors: Caratti o Garatti, A.; Stecklum, B.; Garcia Lopez, R.; Eislöffel, J.; Ray, T. P.; Sanna, A.; Cesaroni, R.; Walmsley, C. M.; Oudmaijer, R. D.; de Wit, W. J.; Moscadelli, L.; Greiner, J.; Krabbe, A.; Fischer, C.; Klein, R.; Ibañez, J. M.