  The burst mode of accretion in massive star formation is a scenario linking
the initial gravitational collapse of parent pre-stellar cores to the
properties of their gravitationally unstable discs and of their
accretion-driven bursts. In this study, we present a series of high-resolution
3D radiation-hydrodynamics numerical simulations for young massive stars formed
out of collapsing 100 Mo molecular cores spinning with several values of the
ratio of rotational-to-gravitational energies beta=5%-9%. The models include
the indirect gravitational potential caused by disc asymmetries. We find that
this modifies the barycenter of the disc, causing significant excursions of the
central star position, which we term stellar wobbling. The stellar wobbling
slows down and protracts the development of gravitational instability in the
disc, reducing the number and magnitude of the accretion-driven bursts
undergone by the young massive stars, whose properties are in good agreement
with that of the burst monitored from the massive protostar M17 MIR. Including
stellar wobbling is therefore important for accurate modeling disc structures.
Synthetic ALMA interferometric images in the millimeter waveband show that the
outcomes of efficient gravitational instability such as spiral arms and gaseous
clumps can be detected for as long as the disc is old enough and has already
entered the burst mode of accretion.
