Newborn jet in the symbiotic system R Aquarii

Context. R Aquarii (R Aqr) is a well-known symbiotic binary that attracted renewed interest during its recent periastron passage, an event that occurs only once every ∼40 years. This passage marks the first to be observed with modern, state-of-the-art instruments. Aims We investigated 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. Methods. We analysed Hα speckle interferometric images obtained one month apart using Fourier techniques. These are complemented by high-resolution optical spectra in the same emission line. Results. Our speckle imaging reveals a newborn two-sided jet orientated in the north-south direction. Its proper motion, 66 ± 19 mas yr^-1, confirms that it was launched around 2020 January 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 μ = 27 ± 17 mas yr^-1 at a position angle of 187 and an ejection time around 2019 October 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.