Disk-mediated accretion burst in a high-mass young stellar object
  Solar-mass stars form via circumstellar disk accretion (disk-mediated
accretion). Recent findings indicate that this process is likely episodic in
the form of accretion bursts, possibly caused by disk fragmentation. Although
it cannot be ruled out that high-mass young stellar objects (HMYSOs; $M>$8
M$_\odot$, $L_{bol}>$5$\times$10$^3$ L$_\odot$) arise from the coalescence of
their low-mass brethren, latest results suggest that they more likely form via
disks. Accordingly, disk-mediated accretion bursts should occur. Here we report
on the discovery of the first disk-mediated accretion burst from a $\sim$20
M$_\odot$ HMYSO. Our near-infrared images show the brightening of the central
source and its outflow cavities. Near-infrared spectroscopy reveals emission
lines typical of accretion bursts in low-mass protostars, but orders of
magnitude more luminous. Moreover, the energy released 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.
