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PR Video eso2601a
An unexpected shock wave | ESO News
PR Video eso2601b
Zooming on a dead star with a strange shock wave around it
PR Video eso2601c
The star RXJ0528+2838 moving through space
PR Video eso2601a
An unexpected shock wave | ESO News
PR Video eso2601b
Zooming on a dead star with a strange shock wave around it
PR Video eso2601c
The star RXJ0528+2838 moving through space
Gas and dust flowing from stars can, under the right conditions, clash with a star’s surroundings and create a shock wave. Now, astronomers using the European Southern Observatory’s Very Large Telescope (ESO’s VLT) have imaged a beautiful shock wave around a dead star — a discovery that has left them puzzled. According to all known mechanisms, the small, dead star RXJ0528+2838 should not have such structure around it. This discovery, as enigmatic as it’s
stunning, challenges our understanding of how dead stars interact with their surroundings.
“We found something never seen before and, more importantly, entirely unexpected,” says Simone Scaringi, associate professor at Durham University, UK and co-lead author of the study published today in Nature Astronomy. “Our observations reveal a powerful outflow that, according to our current understanding, shouldn’t be there,” says Krystian Iłkiewicz, a postdoctoral researcher at the Nicolaus Copernicus AstronomicalCenter in Warsaw, Poland and study co-lead. ‘Outflow’ is the term used by astronomers to describe the material that is ejected from celestial objects.
The star RXJ0528+2838 islocated 730 light-years away and, like the Sun and other stars, it rotates around our galaxy’s centre. As it moves, it interacts with the gas that permeates the space between stars, creating a type of shock wave called a bow shock, “a curved arc of material, similar to the wave that builds up in front of a ship,” explains Noel Castro Segura, research fellow at the University of Warwick in the UK and collaborator in this study. These bow shocks are usually created by material outflowing from the central star, but in the case of RXJ0528+2838, none of the known mechanisms can fully explain the observations
RXJ0528+2838 is a white dwarf — the left-over core of a dying low-mass star — and has a Sun-like companion orbiting it. In such binary systems, the material from the companion star is transferred to the white dwarf, often forming a disc around it. While the disc fuels the dead star, some of the material also gets ejected into space, creating powerful outflows. But RXJ0528+2838 shows no signs of a disc, making the origin of the outflow and resulting nebula around the star a mystery.
The surprise that supposedly quiet, discless system could drive such a spectacular nebula was one of those rare ‘wow’ moments,” says Scaringi.
The team first spotted a strange nebulosity around RXJ0528+2838 on images from the Isaac Newton Telescope in Spain. Noticing its unusual shape, they observed ;it in more detail with the MUSE instrument on ESO’s VLT. “Observations with the ESO MUSE instrument allowed us to map the bow shock in detail and analyse its composition. This was crucial to confirm that the structure really originates from the binary system and not from an unrelated nebula or interstellar cloud,”Iłkiewic explains.
The shape and size of the bow shock imply that the white dwarf has been expelling a powerful outflow for at least 1000 years. Scientists don’t know exactly how a dead star without a disc can power such a long-lasting outflow — but they do have a uess.
This white dwarf is known to host a strong magnetic field, which has been confirmed by the MUSE data. This field channels the material stolen from the companion star directly onto the white dwarf, without forming a disc around it. “Our finding shows that even without a disc, these systems can drive powerful outflows, revealing a mechanism we do not yet understand. This discovery challenges the standard picture of how matter moves and interacts in these extreme binary systems,” Iłkiewicz explains.
The results hint at a hidden energy source, likely the strong magnetic field, but this ‘mystery engine’, as Scaringi puts it, still needs to be investigated. The data show that the current magnetic field is only strong enough to power a bow shock lasting for a few hundred years, so it only partly explains what the astronomers are seeing.
To better understand the nature of such discless outflows, many more binary systems need to be studied. ESO’s upcoming Extremely Large Telescope (ELT) will help astronomers“to map more of these systems as well as fainter ones and detect similar systems in detail, ultimately helping in understanding the mysterious energy source that remains une/xplained,” as Scaringi foresees.
“We found something never seen before and, more importantly, entirely unexpected,” says Simone Scaringi, associate professor at Durham University, UK and co-lead author of the study published today in Nature Astronomy. “Our observations reveal a powerful outflow that, according to our current understanding, shouldn’t be there,” says Krystian Iłkiewicz, a postdoctoral researcher at the Nicolaus Copernicus AstronomicalCenter in Warsaw, Poland and study co-lead. ‘Outflow’ is the term used by astronomers to describe the material that is ejected from celestial objects.
The star RXJ0528+2838 islocated 730 light-years away and, like the Sun and other stars, it rotates around our galaxy’s centre. As it moves, it interacts with the gas that permeates the space between stars, creating a type of shock wave called a bow shock, “a curved arc of material, similar to the wave that builds up in front of a ship,” explains Noel Castro Segura, research fellow at the University of Warwick in the UK and collaborator in this study. These bow shocks are usually created by material outflowing from the central star, but in the case of RXJ0528+2838, none of the known mechanisms can fully explain the observations
RXJ0528+2838 is a white dwarf — the left-over core of a dying low-mass star — and has a Sun-like companion orbiting it. In such binary systems, the material from the companion star is transferred to the white dwarf, often forming a disc around it. While the disc fuels the dead star, some of the material also gets ejected into space, creating powerful outflows. But RXJ0528+2838 shows no signs of a disc, making the origin of the outflow and resulting nebula around the star a mystery.
The surprise that supposedly quiet, discless system could drive such a spectacular nebula was one of those rare ‘wow’ moments,” says Scaringi.
The team first spotted a strange nebulosity around RXJ0528+2838 on images from the Isaac Newton Telescope in Spain. Noticing its unusual shape, they observed ;it in more detail with the MUSE instrument on ESO’s VLT. “Observations with the ESO MUSE instrument allowed us to map the bow shock in detail and analyse its composition. This was crucial to confirm that the structure really originates from the binary system and not from an unrelated nebula or interstellar cloud,”Iłkiewic explains.
The shape and size of the bow shock imply that the white dwarf has been expelling a powerful outflow for at least 1000 years. Scientists don’t know exactly how a dead star without a disc can power such a long-lasting outflow — but they do have a uess.
This white dwarf is known to host a strong magnetic field, which has been confirmed by the MUSE data. This field channels the material stolen from the companion star directly onto the white dwarf, without forming a disc around it. “Our finding shows that even without a disc, these systems can drive powerful outflows, revealing a mechanism we do not yet understand. This discovery challenges the standard picture of how matter moves and interacts in these extreme binary systems,” Iłkiewicz explains.
The results hint at a hidden energy source, likely the strong magnetic field, but this ‘mystery engine’, as Scaringi puts it, still needs to be investigated. The data show that the current magnetic field is only strong enough to power a bow shock lasting for a few hundred years, so it only partly explains what the astronomers are seeing.
To better understand the nature of such discless outflows, many more binary systems need to be studied. ESO’s upcoming Extremely Large Telescope (ELT) will help astronomers“to map more of these systems as well as fainter ones and detect similar systems in detail, ultimately helping in understanding the mysterious energy source that remains une/xplained,” as Scaringi foresees.
Source: ESO/News
More information
This research was presented in a paper titled “A persistent bow shock in a diskless magnetised accreting white dwarf” to appear in Nature Astronomy (doi: 10.1038/s41550-025-02748-8).
The team is composed of Krystian Iłkiewicz (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Warsaw, Poland and Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham, UK [CEA Durham]), Simone Scaringi (CEA Durham and INAF-Osservatorio Astronomico di Capodimonte, Naples, Italy [Capodimonte]), Domitilla de Martino (Capodimonte), Christian Knigge (Department of Physics & Astronomy, University of Southampton, Southampton, UK), Sara E. Motta (Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Brera, Merate, Italy and University of Oxford, Department of Physics, Oxford, UK [Oxford]), Nanda Rea (Institute of Space Sciences (ICE, CSIC), Barcelona, Spain and Institut d’Estudis Espacials de Catalunya (IEEC), Castelldefels, Spain), David Buckley (South African Astronomical Observatory, South Africa [SAAO] and Department of Astronomy & IDIA, University of Cape Town, Rondebosh, South Africa [Cape Town] and Department of Physics, University of the Free State, Bloemfontein, South Africa), Noel Castro Segura (Department of Physics, University of Warwick, Coventry, UK), Paul J. Groot (SAAO and Cape Town and Department of Astrophysics/IMAPP, Radboud University, Nijmegen, The Netherlands), Anna F. McLeod (CEA Durham and Institute for Computational Cosmology, Department of Physics, University of Durham, Durham UK), Luke T. Parker (Oxford), and Martina Veresvarska (CEA Durham).
The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration for astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 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’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as survey telescopes such as VISTA. Also at Paranal, ESO will host and operate the south array of the Cherenkov Telescope Array Observatory, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates ALMA on Chajnantor, a facility that observes the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago, Chile we support our operations in the country and engage with Chilean partners and society.
The team is composed of Krystian Iłkiewicz (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Warsaw, Poland and Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham, UK [CEA Durham]), Simone Scaringi (CEA Durham and INAF-Osservatorio Astronomico di Capodimonte, Naples, Italy [Capodimonte]), Domitilla de Martino (Capodimonte), Christian Knigge (Department of Physics & Astronomy, University of Southampton, Southampton, UK), Sara E. Motta (Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Brera, Merate, Italy and University of Oxford, Department of Physics, Oxford, UK [Oxford]), Nanda Rea (Institute of Space Sciences (ICE, CSIC), Barcelona, Spain and Institut d’Estudis Espacials de Catalunya (IEEC), Castelldefels, Spain), David Buckley (South African Astronomical Observatory, South Africa [SAAO] and Department of Astronomy & IDIA, University of Cape Town, Rondebosh, South Africa [Cape Town] and Department of Physics, University of the Free State, Bloemfontein, South Africa), Noel Castro Segura (Department of Physics, University of Warwick, Coventry, UK), Paul J. Groot (SAAO and Cape Town and Department of Astrophysics/IMAPP, Radboud University, Nijmegen, The Netherlands), Anna F. McLeod (CEA Durham and Institute for Computational Cosmology, Department of Physics, University of Durham, Durham UK), Luke T. Parker (Oxford), and Martina Veresvarska (CEA Durham).
The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration for astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 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’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as survey telescopes such as VISTA. Also at Paranal, ESO will host and operate the south array of the Cherenkov Telescope Array Observatory, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates ALMA on Chajnantor, a facility that observes the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago, Chile we support our operations in the country and engage with Chilean partners and society.
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Contacts:
Krystian Iłkiewicz
Nicolaus Copernicus Astronomical Center
Warsaw, Poland
Tel: +48 223296134
Email: ilkiewicz@camk.edu.pl
Simone Scaringi
Centre for Extragalactic Astronomy, Department of Physics, Durham University
Durham, UK
Cell: +44 7737 980235
Email: simone.scaringi@durham.ac.uk
Noel Castro Segura
Department of Physics, University of Warwick
Coventry, UK
Tel: +44 7859 761377
Email: noel.castro-segura@warwick.ac.uk
Bárbara Ferreira
ESO Media Manager
Garching bei München, Germany
Tel: +49 89 3200 6670
Cell: +49 151 241 664 00
Email: press@eso.org
