ALMA observations of the disk-outflow system in S255IR-SMA1 at ~15 mas (~20 au) resolution

The S255IR-SMA1 core harbours a 20 Msun protostar NIRS3. Several years ago, a first disk-mediated accretion burst was detected there. We have studied this object for a long time with various instruments, including ALMA. Our first ALMA observations have ~150 mas resolution. In 2021 new observations with an order of magnitude higher resolution were performed. The main results are as follows. An emission of the ionized envelope around the NIR3 protostar is probably observed. A clumpy sub-Keplerian disk around the NIR3 protostar ~400 AU in diameter with signatures of infall is observed in several molecular lines. A submillimeter emission from the jet is observed, which apparently represents a free-free emission of the ionized gas. There are several knots along the jet with the intervals between them ~100 au. The jet orientation differs by ~20∘ from that on larger scales, which may indicate a jet precession. The CH3OH 141-140 and 121-120 A-+ maser emission is detected around the jet.