Newborn jet in the symbiotic system R Aquarii

TL;DR

This study observes a newly formed two-sided jet in the R Aquarii symbiotic system during its recent periastron, revealing jet-launching mechanisms through speckle imaging and spectroscopy, and updating the system's distance.

Contribution

First direct imaging and analysis of a newborn jet in R Aqr during periastron, providing insights into jet-launching processes in symbiotic binaries.

Findings

Detected a two-sided jet launched around January 2020.

Measured the jet's proper motion at 66 ± 19 mas/year.

Updated the distance to R Aqr to 260 parsecs.

Abstract

R Aquarii (R Aqr) is a well-known symbiotic binary that has attracted renewed interest during its recent periastron passage, an event that occurs only once every about 40 years. This passage marks the first to be observed with modern, state-of-the-art instruments. We investigate the inner, sub-arcsecond active region of R Aqr during this recent periastron passage, with the goal of gaining insight into the jet-launching mechanisms at work in this system. We analyse Ha speckle interferometric images obtained one month apart using Fourier techniques. These are complemented by high-resolution optical spectra in the same emission line. Our speckle imaging reveals a newborn two-sided jet orientated in the north-south direction. Its proper motion, 66 +- 19 mas per year, confirms that it was launched around 2020 Jan 7, at the onset of the periastron passage. Further analysis of the elongated central structure reveals a knot in the southern counterpart of the jet, moving away from the binary with a 27 +- 17 mas per year at a position angle of 187 degrees, and an ejection time around 2019 Oct 28. This interpretation is further supported by our high-resolution spectroscopic data. In addition, we update the expansion parallax distance of R Aqr to 260 pc.