G22 is a hub-filament system composed of four supercritical filaments. Velocity gradients are detected along three filaments. A total mass infall rate of 440 $M_\odot$~Myr$^{ -1}$ would double the hub mass in about six free-fall times. The most massive clump C1 would be in global collapse with an infall velocity of 0.31 km s$^{ -1}$ and a mass infall rate of $ 7.2\times10^{ -4} $ $M_\odot$ yr$^{ -1}$, which is supported by the prevalent HCO$^+$ (3-2) and $^{ 13}$CO (3-2) blue profiles. A hot molecular core (SMA1) was revealed in C1. At the SMA1 center, there is a massive protostar (MIR1) driving multipolar outflows which are associated with clusters of class I methanol masers. MIR1 may be still growing with an accretion rate of $7\times10^{ -5}$ $M_\odot$ yr$^{ -1}$. Filamentary flows, clump-scale collapse, core-scale accretion coexist in G22, suggesting that high-mass starless cores may not be prerequisite to form high-mass stars. In the high-mass star formation process, the central protostar, the core, and the clump can grow in mass simultaneously.
Categories: astro-ph.GA astro-ph.SR