The jet of the young star RW Aur A and related problems

TL;DR

This study analyzes the jet of young star RW Aur A over 21 years, linking jet knot emergence and star dimming events to disk restructuring caused by a companion star, revealing insights into star-disk interactions.

Contribution

It proposes a new explanation for jet knot formation and asymmetry based on disk restructuring due to a stellar fly-by and tidal effects.

Findings

Outer jet knots emerged approximately 350 years ago.

Deep, long-lasting dimmings of RW Aur A occurred after 2010.

Asymmetry in jet parameters linked to circumstellar matter distribution.

Abstract

Comparing the images of the jet of the young star RW Aur A, separated by a period of 21.3 years, we found that the outermost jet's knots have emerged $\approx 350$ yr ago. We argue that at that moment the jet itself has appeared and intensive accretion onto the star has began due to the rearrangement of its protoplanetary disk structure caused by the tidal effect of the companion RW Aur B. More precisely, we assume that the increase of accretion is a response to changing conditions in the outer disk regions, which followed after the sound wave, generated by these changes, crossed the disk in a radial direction. The difference in the parameters of the blue and red lobes of the RW Aur A jet, according to our opinion, is a result of the asymmetric distribution of the circumstellar matter above and below the disk, due to a fly-by of the companion. It was found from the analysis of RW Aur historical light curve that deep and long $(\Delta t>150$ days) dimmings of RW Aur A observed after 2010 yr, had no analogues in the previous 110 years. We also associate the change in the character of the photometric variability of the star with the rearrangement of the structure of inner $(r<1$ a.u.) regions of its protoplanetary disk and discuss why these changes began only 350 years after the beginning of the active accretion phase.