New insights into the outflows from R Aquarii

¹ Tartu Observatory, Observatooriumi 1, Tõravere 61602, Estonia
e-mail: tiina@obs.ee
² Institute of Physics, University of Tartu, Ravila 14c, Tartu 50411, Estonia
³ GRANTECAN, Cuesta de San José s/n, 38712 Breña Baja, La Palma, Spain
⁴ Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
⁵ Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
⁶ Kapteyn Instituut, Rijksuniversiteit Groningen, Landleven 12, 9747AD Groningen, The Netherlands
⁷ Observatorio Astronómico Nacional (OAN-IGN), C/ Alfonso XII, 3, 28014 Madrid, Spain
⁸ Terroux Observatory, Canberra, Australia
⁹ Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN, UK
¹⁰ Nordic Optical Telescope, Apartado 474, 38700 Santa Cruz de La Palma, Spain
¹¹ Leiden Observatory, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands
¹² CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98bis Boulevard Arago, 75014 Paris, France

Received: 10 October 2017
Accepted: 23 January 2018

Abstract

Context. The source 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.

Aims. We aim to study 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.

Methods. Narrow-band images acquired over a period of more than 21 yr were compared in order to study the expansion and evolution of all components of the R Aqr nebula. The magnification method was used to derive the kinematic ages of the features that appear to expand radially. Integral field spectroscopy of the [O III] 5007 Å emission is used to study the velocity structure of the central regions of the jet.

Results. 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 yr old, while the inner regions have ages ranging from 125 to 290 yr. 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.