Press Release

Dancing with the Enemy

ESO’s R Aquarii Week continues with the sharpest R Aquarii image ever

12 December 2018

While testing a new subsystem on the SPHERE planet-hunting instrument on ESO’s Very Large Telescope, astronomers were able to capture dramatic details of the turbulent stellar relationship in the binary star R Aquarii with unprecedented clarity — even compared to observations from Hubble.

This spectacular image — the second instalment in ESO’s R Aquarii Week — shows intimate details of the dramatic stellar duo making up the binary star R Aquarii. Though most binary stars are bound in a graceful waltz by gravity, the relationship between the stars of R Aquarii is far less serene. Despite its diminutive size, the smaller of the two stars in this pair is steadily stripping material from its dying companion — a red giant.

Years of observation have uncovered the peculiar story behind the binary star R Aquarii, visible at the heart of this image. The larger of the two stars, the red giant, is a type of star known as a Mira variable. At the end of their life, these stars start to pulsate, becoming 1000 times as bright as the Sun as their outer envelopes expand and are cast into the interstellar void.

The death throes of this vast star are already dramatic, but the influence of the companion white dwarf star transforms this intriguing astronomical situation into a sinister cosmic spectacle. The white dwarf — which is smaller, denser and much hotter than the red giant — is flaying material from the outer layers of its larger companion. The jets of stellar material cast off by this dying giant and white dwarf pair can be seen here spewing outwards from R Aquarii.

Occasionally, enough material collects on the surface of the white dwarf to trigger a thermonuclear nova explosion, a titanic event which throws a vast amount of material into space. The remnants of past nova events can be seen in the tenuous nebula of gas radiating from R Aquarii in this image.

R Aquarii lies only 650 light-years from Earth — a near neighbour in astronomical terms — and is one of the closest symbiotic binary stars to Earth. As such, this intriguing binary has received particular attention from astronomers for decades. Capturing an image of the myriad features of R Aquarii was a perfect way for astronomers to test the capabilities of the Zurich IMaging POLarimeter (ZIMPOL), a component on board the planet-hunting instrument SPHERE. The results exceeded observations from space — the image shown here is even sharper than observations from the famous NASA/ESA Hubble Space Telescope.

SPHERE was developed over years of studies and construction to focus on one of the most challenging and exciting areas of astronomy: the search for exoplanets. By using a state-of-the-art adaptive optics system and specialised instruments such as ZIMPOL, SPHERE can achieve the challenging feat of directly imaging exoplanets. However, SPHERE’s capabilities are not limited to hunting for elusive exoplanets. The instrument can also be used to study a variety of astronomical sources — as can be seen from this spellbinding image of the stellar peculiarities of R Aquarii.

More information

This research was presented in the paper “SPHERE / ZIMPOL observations of the symbiotic system R Aqr. I. Imaging of the stellar binary and the innermost jet clouds” by H.M. Schmid et. al, which was published in the journal Astronomy & Astrophysics.

The team was composed of H. M. Schmid (ETH Zurich, Institute for Astronomy, Switzerland), A. Bazzon (ETH Zurich, Institute for Astronomy, Switzerland), J. Milli (European Southern Observatory), R. Roelfsema (NOVA Optical Infrared Instrumentation Group at ASTRON, the Netherlands), N. Engler (ETH Zurich, Institute for Astronomy, Switzerland) , D. Mouillet (Université Grenoble Alpes and CNRS, France), E. Lagadec (Université Côte d’Azur, France), E. Sissa (INAF and Dipartimento di Fisica e Astronomia “G. Galilei” Universitá di Padova, Italy), J.-F. Sauvage (Aix Marseille Univ, France), C. Ginski (Leiden Observatory and Anton Pannekoek Astronomical Institute, the Netherlands), A. Baruffolo (INAF), J.L. Beuzit (Université Grenoble Alpes and CNRS, France), A. Boccaletti (LESIA, Observatoire de Paris, France), A. J. Bohn (ETH Zurich, Institute for Astronomy, Switzerland), R. Claudi (INAF, Italy), A. Costille (Aix Marseille Univ, France), S. Desidera (INAF, Italy), K. Dohlen (Aix Marseille Univ, France), C. Dominik (Anton Pannekoek Astronomical Institute, the Netherlands), M. Feldt (Max-Planck-Institut für Astronomie, Germany), T. Fusco (ONERA, France), D. Gisler (Kiepenheuer-Institut für Sonnenphysik, Germany), J.H. Girard (European Southern Observatory), R. Gratton (INAF, Italy), T. Henning (Max-Planck-Institut für Astronomie, Germany), N. Hubin (European Southern Observatory), F. Joos (ETH Zurich, Institute for Astronomy, Switzerland), M. Kasper (European Southern Observatory), M. Langlois (Centre de Recherche Astrophysique de Lyon and Aix Marseille Univ, France), A. Pavlov (Max-Planck-Institut für Astronomie, Germany), J. Pragt (NOVA Optical Infrared Instrumentation Group at ASTRON, the Netherlands), P. Puget (Université Grenoble Alpes, France), S.P. Quanz (ETH Zurich, Institute for Astronomy, Switzerland), B. Salasnich (INAF, Italy), R. Siebenmorgen (European Southern Observatory), M. Stute (Simcorp GmbH, Germany), M. Suarez (European Southern Observatory), J. Szulagyi (ETH Zurich, Institute for Astronomy, Switzerland), C. Thalmann (ETH Zurich, Institute for Astronomy, Switzerland), M. Turatto (INAF, Italy), S. Udry (Geneva Observatory, Switzerland), A. Vigan (Aix Marseille Univ, France), and F. Wildi (Geneva Observatory, Switzerland).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It has 16 Member States: Austria, Belgium, Czechia, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and with Australia as a Strategic Partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.