The unique supernova SN 1987A has been a bonanza for astrophysicists. It provided several observational 'firsts,' like the detection of neutrinos from an exploding star, the observation of the progenitor star on archival photographic plates, the signatures of a non-spherical explosion, the direct observation of the radioactive elements produced during the blast, observation of the formation of dust in the supernova, as well as the detection of circumstellar and interstellar material.
Today, it is exactly twenty years since the explosion of Supernova 1987A in the Large Magellanic Cloud was first observed, at a distance of 163,000 light-years. It was the first naked-eye supernova to be seen for 383 years. Few events in modern astronomy have met with such an enthusiastic response by the scientists and now, after 20 years, it continues to be an extremely exciting object that is further studied by astronomers around the world, in particular using ESO's telescopes.
When the first signs of Supernova 1987A, the first supernova of the year 1987, were noticed early on 24 February of that year, it was clear that this would be an unusual event. It was discovered by naked-eye and on a panoramic photographic plate taken with a 10-inch astrograph on Las Campanas in Chile by Oscar Duhalde and Ian Shelton, respectively. A few hours earlier, still on 23 February, two large underground proton-decay detectors in Japan had registered the passage of high-energy neutrinos.
Since SN 1987A exploded in the Large Magellanic Cloud (LMC), it was only accessible to telescopes in the Southern Hemisphere, more particularly in Australia, South Africa, and South America. In Chile, ESO's observatory at La Silla with its armada of telescopes with sizes between 0.5 and 3.6-m, played an important role.
Astronomers John Danziger and Patrice Bouchet, who were there at the time, recall: "When astronomers at La Silla arrived for the ritual afternoon tea at 4pm on the 24th February 1987 after the previous night's clear observing, they were greeted by the news that a supernova had been detected in the LMC the previous night. The tea-time ritual of groggy astronomers quietly sipping their tea was transformed, to be succeeded by flurries of excited but still to some extent uncoordinated planning. Nobody doubted for one second that the sky would be clear and there would be excitement galore in the days and nights ahead. And indeed there was!
A large observatory such as La Silla with its many telescopes can be considered like a naval fleet consisting of many ships from torpedo boats to cruisers and even aircraft carriers. La Silla had them all. All observers were encouraged to plan for observing SN1987A by whatever means at their disposal."
"Ironically, the supernova was too bright for the state-of-the-art 4m-class telescopes and some of them had to be stopped down, e.g. by half-closed telescope covers," says Jason Spyromilio (ESO). "Some of the smaller telescopes took their chance. The 61-cm Bochum telescope on La Silla was used, on a nearly daily basis for more than a year, to measure optical spectroscopy with photometric accuracy. Since the LMC is circumpolar for most southern observatories, this also meant that we have an uninterrupted record of the photometry and spectroscopy; else we would have missed part of the peak phase, which lasted into May of 1987."
By July, the first conference on SN 1987A, organised by John Danziger, had already taken place at ESO in Garching to be followed by several others during that year and following years.
The optical light curve of SN 1987A was rather different from those of previously observed core-collapse supernovae. The old models of spherical explosions had to be revised. The spectroscopic evolution provided further evidence for asymmetries in the explosion. The 'Bochum event' was a rapid change in the line profile observed with the Bochum telescope on La Silla. It is the signature of a radioactive blob rising from the inner ejecta to the surface. "The picture emerging from the observations of the first several weeks was certainly more complex than what had ever been assumed of supernovae before," says Bruno Leibundgut (ESO).
The 1-m telescope at La Silla was also extensively used in daytime observing the supernova in the near- and mid-infrared for more than one year after the explosion. A clear excess emission developed in the near-infrared already 10 days after the explosion, the origin of which is still not fully understood. It was most probably due to circumstellar material that was lighted up by the explosion.
Dust condensation in the ejecta was discovered by spectroscopy about 500 days after the explosion. Macroscopic dust grains partially covered the ejecta, and most probably still do. They might explain why no compact object is seen at the location of the supernova.
In 1989, when the NTT came into operation, it imaged for the first time the circumstellar ring around SN 1987A. And, about three years after the explosion, NTT images revealed a circumstellar structure around SN 1987A which resembled the triangular hat which Napoleon wore. Napoleon's hat gave the first opportunity for a 3-dimensional view of SN 1987A.
"The existence of the ring presents an unsolved puzzle for SN 1987A," says Roberto Gilmozzi (ESO). "Even though it is not clear how to construct such a ring, it is likely that the star that exploded as SN 1987A had a companion."
When ESO's Very Large Telescope came into operation, the interest in the supernova had not faded away. Far from it! Observations were done with the VLT's many instruments, including FORS, UVES, ISAAC, and VISIR, to probe in more detail the surroundings of the explosion. More recently, adaptive optics instruments, which compensate for the blurring effect of the atmosphere, and so can see as if they were in space, have also been used. The NACO instrument has obtained amazing images of the rings, while SINFONI has been used to study the changes in the rings' appearances and the evolution of the spectral lines.
"SN 1987A was full of surprises and it remains unique amongst the known supernovae," says Leibundgut. "Not only was it the closest supernova for several centuries, it was also very peculiar, coming from a blue supergiant progenitor, with a circumstellar environment unlike any other supernova known. We will certainly continue to monitor its evolution for many years to come."
One goal will be to find the possible compact object that should have survived the dramatic explosion. But until now, this remnant has proved elusive.
Henri Boffin | alfa
DGIST develops 20 times faster biosensor
24.04.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)
New quantum liquid crystals may play role in future of computers
21.04.2017 | California Institute of Technology
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences