New insights into the outflows from R Aquarii

TL;DR

This study uses long-term optical imaging and spectroscopy to analyze the evolution, kinematics, and structure of the nebula and jets in R Aquarii, revealing new features, age estimates, and complex velocity behaviors.

Contribution

It provides new extended features, refined age estimates, and detailed velocity structures of R Aquarii's nebula and jets, enhancing understanding of symbiotic binary outflows.

Findings

Detected new extended features beyond the known nebula.

Estimated the nebula's age at approximately 650 years.

Found complex velocity deviations in the jets, with asymmetries in red and blue shifts.

Abstract

R Aquarii is a symbiotic binary surrounded by a large and complex nebula with a prominent curved jet. It is one of the closest known symbiotic systems, and therefore offers a unique opportunity to study the central regions of these systems and the formation and evolution of astrophysical jets. We studied the evolution of the central jet and outer nebula of R Aqr taking advantage of a long term monitoring campaign of optical imaging, as well as of high-resolution integral field spectroscopy. Narrow-band images acquired over a period of more than 21 years are compared in order to study the expansion and evolution of all components of the R Aqr nebula. The magnification method is used to derive the kinematic ages of the features that appear to expand radially. Integral field spectroscopy of the OIII 5007A emission is used to study the velocity structure of the central regions of the jet. New extended features, further out than the previously known hourglass nebula, are detected. The kinematic distance to R Aqr is calculated to be 178 pc using the expansion of the large hourglass nebula. This nebula of R Aqr is found to be roughly 650 years old, while the inner regions have ages ranging from 125 to 290 years. The outer nebula is found to be well described by a ballistic expansion, while for most components of the jet strong deviations from such behaviour are found. We find that the Northern jet is mostly red-shifted while its Southern part is blue-shifted, apparently at odds with findings from previous studies but almost certainly a consequence of the complex nature of the jet and variations in ionisation and illumination between observations.