Astronomers have taken the sharpest image yet of the sky at very long radio wavelengths. The image shows the centre of the galaxy Messier 82 (M 82), also known as the Cigar Galaxy, 11.5 million light years from Earth. M 82 is forming stars much faster than our galaxy, the Milky Way, and is a favourite object for many astronomers who investigate the evolution of stars and galaxies.
In images taken in visible light, M 82 is a riot of stars, gas and dust. Lofar shows us a completely different scene.
– In Lofar’s new extremely sharp image we’re seeing a collection of bright spots, which are most likely supernova remnants, explains Eskil Varenius (Chalmers), who led the international team of scientists behind the new image.
A supernova remnant is a shining shell of shock waves from an exploded star, ploughing into its surroundings. Supernova remnants are huge objects by everyday standards, much larger than the size of our own solar system, but look small from a distance.
– This galaxy is millions of light years away, and each remnant can be as little as a few light years across. We need extremely sharp images to study them, says Eskil Varenius.
The supernova remnants are embedded inside a huge, diffuse cloud of charged particles, or plasma, which absorbs radio waves from these sources. By investigating how different wavelengths pass through the plasma, scientists can learn more about how a gigantic star factory like M 82 works.
– We’re surprised that Lofar can see as many as 16 bright supernova remnants in M 82. This image can give us new clues to the structure of M 82 and why so many stars are being formed there, says John Conway, part of the team and director of Onsala Space Observatory where Sweden’s Lofar station is located.
This exciting image of M 82 is the first of many that Lofar and its international stations will be able to give us. The scientists are now working on new super-sharp Lofar images of other galaxies.
– Lofar is showing us the sky in a way that we’ve never seen before, and in in exquisite detail. This beautiful image is just a foretaste of what the telescope is capable of, says Mike Garrett, director of Astron, the Netherlands Institute for Radio Astronomy.
Image: The centre of the galaxy M 82 at very long radio wavelengths (2.5 m/118 MHz [orange] and 1.9 m/154 MHz [blue]). The bright points are most likely supernova remnants. The image is about 3300 light years across.
Credit: E. Varenius/Onsala Space Observatory/Lofar collaboration
Robert Cumming, astronomer and communcations officer, Onsala Space Observatory, Chalmers, +46 31-772 5500, +46 70-493 31 14, firstname.lastname@example.org
The Swedish station in the giant radio telescope Lofar is located at Onsala Space Observatory, 45 km south of Gothenburg.
Credit: Onsala Space Observatory/R. Hammargren
About Lofar, the SKA and Onsala Space Observatory
Lofar (Low Frequency Array) is a radio telescope which consists of thousands of antennas spread across northern Europe with its core in the Netherlands. The telescope is uniquely sensitive to the very longest radio waves that can penetrate Earth’s atmosphere.
Lofar is designed and built by Astron, the Netherlands Institute for Radio Astronomy. The International Lofar Telescope has 38 stations in the Netherlands, six in Germany, and one each in France, Sweden and the United Kingdom. Three further stations are under construction in Poland.
Lofar is a scientific and technological pathfinder for the Square Kilometre Array (SKA). The SKA is a global science and engineering project to build the world’s largest radio telescope be built in radio-quiet locations in Africa and Australia. The SKA brings together 11 countries from across the planet, corresponding to 40% of the world’s population. Sweden became a member of the SKA in 2012. Sweden is represented in the SKA Organisation by Onsala Space Observatory.
Onsala Space Observatory is the Swedish national facility for radio astronomy. The observatory provides researchers with equipment for the study of the Earth and the rest of the universe. In Onsala, 45 km south of Gothenburg, it operates two radio telescopes and a station in the international telescope Lofar, and also equipment for earth and atmospheric sciences. It also participates in several international projects. The observatory is hosted by the Department of Earth and Space Sciences at Chalmers University of Technology, and is operated on behalf of the Swedish Research Council.
About the research
The research is published in the paper Subarcsecond international LOFAR radio images of the M82 nucleus at 118 MHz and 154 MHz
by E. Varenius et al., to be published shortly in Astronomy & Astrophysics. A version of the paper is available online at http://arxiv.org/abs/1411.7680
The team is comprised of Eskil Varenius (Chalmers), John E. Conway (Onsala Space Observatory, Chalmers), Ivan Martí-Vidal (Onsala Space Observatory, Chalmers), R. Beswick (University of Manchester, United Kingdom), A. T. Deller (Astron, Netherlands), O. Wucknitz (Max-Planck-Institut für Radioastronomie [MPIfR], Germany), N. Jackson (Manchester), B. Adebahr (MPIfR), M. A. Pérez-Torres (Instituto de Astrofísica de Andalucía, Spain), K. T. Chyży (Jagiellonian University, Krakow, Poland), Tobia D. Carozzi (Onsala Space Observatory, Chalmers), J. Moldón (Astron), Susanne Aalto (Chalmers), R. Beck (MPIfR), P. Best (Royal Observatory Edinburgh, United Kingdom), R.-J. Dettmar (Ruhr-Universität Bochum, Germany), W. van Driel (Observatoire de Paris, France), G. Brunetti (INAF-Istituto di Radioastronomia, Bologna, Italy), M. Brüggen (University of Hamburg, Germany), M. Haverkorn (Radboud University and Leiden University, Netherlands), G. Heald (Astron/KAI), Cathy Horellou (Chalmers), M. J. Jarvis (University of Oxford, United Kingdom), L. K. Morabito (Leiden University), G. K. Miley (Leiden University, Netherlands), H. J. A. Röttgering (Leiden University), M. C. Toribio (Astron) and G. J. White (Open University and RAL, UK).