The last piece of a supernova puzzle
A team led by Gastón Folatelli at the Kavli IPMU, the University of Tokyo, has found evidence of a hot binary companion star to a yellow supergiant star, which had become a bright supernova. The existence of the companion star had been predicted by the same team on the basis of numerical calculations.
Images in the top row depict an artist's conception of the supernova explosion process. The corresponding images below were taken with the Hubble Space Telescope. Left: Just before the supernova explosion. A yellow supergiant is shining. Middle: The supernova exploding (the bottom image shows the fading supernova after the explosion). Right: A bright blue star observed.
Credit: Top image: Kavli IPMU Bottom image: NASA/Kavli IPMU/Gastón Folatelli
This finding provides the last link in a chain of observations that have so far supported the team's theoretical picture for this supernova. The results are published in the Astrophysical Journal Letters and have wide implications for our knowledge of binary systems and supernova mechanisms.
"One of the most exciting moments in my career as an astronomer was when I displayed the newly arrived HST images and saw the object right there, where we had anticipated it to be all along" said Gastón Folatelli , who led the efforts to obtain the new Hubble Space Telescope (HST) observations.
The question of how massive stars spend their short lives until they become supernovae is of great interest for astrophysicists. According to the standard theory, which is only applicable to isolated stars, only cool and extended (red supergiants) or hot and blue (Wolf-Rayet stars) are able to become supernovae.
However, growing evidence suggests that most massive stars are not lonely singles but they belong to close binary systems with profuse interactions. Episodes of mass transfer between the members of binary star systems affect the way the stars evolve, meaning that there are a great many more potential scenarios for the final stages of supernova progenitors.
The nearby supernova SN 2011dh, which occurred in 2011 in the well-known whirlpool galaxy M51, which is about 24 million light-years away from the earth, presented an excellent example that could not be explained by the standard theory. What appeared to be a yellow supergiant star was detected at the location of the supernova in images obtained before the explosion, but yellow supergiant stars in isolation were not thought capable of becoming supernovae.
Controversy arose in the astronomy community with several experts proposing that the actual progenitor must have been an unseen bright blue object, such as a Wolf Rayet star. However, the team led by Melina C. Bersten at Kavli IPMU and Omar Benvenuto at the University of La Plata, Argentina, showed that the exploding star must have been extended, like a yellow supergiant, and that it must have belonged to a binary system (see web release on September 28 2012: http://www.ipmu.jp/node/1404). "We produced detailed models that self-consistently explained every property of SN 2011dh through the explosion of a yellow supergiant star in a binary system," remarked Melina C. Bersten.
In March 2013, the proposal of Benvenuto, Bersten and collaborators was given substantial support when the disappearance of the yellow supergiant was observed, indicating that it and not a bright blue star was the exploding object (see web release on Apr. 5 2013: http://www.ipmu.jp/node/1537). "At that time there was just one piece of the puzzle missing to confirm our model: we had to find the companion star that, according to our calculations, was a hot, compact object," said Omar Benvenuto.
With that goal, the group set out to obtain HST observing time, which was granted in 2013 and recently executed on August 7, 2014. Images were obtained in the ultraviolet regime, where the companion star was expected to be most clearly visible. A point source was clearly detected in the new images at the exact location of the supernova (see announcement in http://www.astronomerstelegram.org/?read=6375). "To our excitement, the object had the properties predicted by the models," explained Schuyler Van Dyk, of Caltech, who was in charge of the image analysis. Folatelli and collaborators judged it unlikely that the detection was due to some other contaminating source.
Further HST observations were recently obtained in the optical range by another European team. "When available, such data will not only serve to definitely validate the existence of the companion star, but also they will provide critical information to refine the binary model originally proposed by our team", said Ken'ichi Nomoto from Kavli IPMU. This is a unique opportunity to make such a detailed study of the progenitor of a supernova. The results will have important implications for our knowledge of stellar evolution and its connection with supernova properties.
The case of SN 2011dh beautifully illustrates the advantages of an active feedback between theory and observation. "As a scientist, for me it is like a dream come true to make a prediction and have it confirmed step by step as the supernova evolves and facts are revealed. It is a rare case for astronomy, where events usually take much longer to develop. We are very happy with how the story of SN 2011dh proceeded," concluded Melina C. Bersten.
Gastón Folatelli, Melina C. Bersten, Omar G. Benvenuto, Schuyler D. Van Dyk, Hanindyo Kuncarayakti, Keiichi Maeda, Takaya Nozawa, Ken'ichi Nomoto, Mario Hamuy, and Robert M. Quimby, "A Blue Point Source at the Location of Supernova 2011dh," Astrophysical Journal Letters.
Gastón Folatelli, Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo
Melina C. Bersten, Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo
Ken'ichi Nomoto, Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo
Marina Komori, Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo
+81-4-7136-5977 (office), +81-80-9343-3171 (mobile), firstname.lastname@example.org
Aya Tsuboi, Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo
ABOUT KAVLI IPMU
Kavli IPMU (Kavli Institute for the Physics and Mathematics of the Universe) is an international research institute with English as its official language. The goal of the institute is to discover the fundamental laws of nature and to understand the Universe from the synergistic perspectives of mathematics, astronomy, and theoretical and experimental physics. The Institute for the Physics and Mathematics of the Universe (IPMU) was established in October 2007 under the World Premier International Research Center Initiative (WPI) of the Ministry of Education, Sports, Science and Technology in Japan with the University of Tokyo as the host institution. IPMU was designated as the first research institute within Todai Institutes for Advanced Study (TODIAS) in January 2011. It received an endowment from The Kavli Foundation and was renamed the "Kavli Institute for the Physics and Mathematics of the Universe" in April 2012. Kavli IPMU is located on the Kashiwa campus of the University of Tokyo, and more than half of its full-time scientific members come from outside Japan.
Kavli IPMU Website - http://www.ipmu.jp/
Marina Komori | Eurek Alert!
Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1
21.03.2018 | Fraunhofer-Institut für Hochfrequenzphysik und Radartechnik FHR
Taming chaos: Calculating probability in complex systems
21.03.2018 | American Institute of Physics
An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.
The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...
In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.
Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.
They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...
For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.
In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...
19.03.2018 | Event News
16.03.2018 | Event News
13.03.2018 | Event News
22.03.2018 | Trade Fair News
22.03.2018 | Earth Sciences
22.03.2018 | Earth Sciences