Project Information AT A GLANCE
Project Title: Astrophysical Processes: their simulation, and related nuclear physics issues FISH: FaInt Supernovae and Hypernova
Project Objective: Stellar evolution of massive stars leads to final explosive endpoints like supernovae, faint supernovae, hypernovae, which form central neutron stars or black holes. The two projects are related to these two different types of outcome and aim to (a) understand the explosion mechanisms and (b) the ejecta composition, impacting the evolution of galaxies.
Fig. 4 - Conditions from core collapse of a massive star, 31ms after reaching central densities as high as in atomic nuclei. Strong magnetic fields wound up by fast rotation (white field lines) cause the ejection of neutron-rich matter along the poles (box dimensions 700 × 700 × 1400 km). The entropy per nucleon, a measure of thermal energy per temperature, is given via color contours.
the heaviest elements, and these are possible at earlier metallicities. The result was published earlier this year. Telescopes detect light from stellar
surfaces, however, there are limitations to what can be determined about stellar evolution and the processes in the interior, as Professor Thielemann points out.
“The centre is burning but the
surface composition is not changing – it stays the same as when the star was born.” Neutrinos, on the other hand, can provide information about the star’s core.
They interact very
that remain. At present Professor Thielemann and his colleague Matthias Liebendörfer are working on a discrepancy of a factor of three between the calculated and observed energy released in supernovae explosions. “That has been a problem for 30 years,” he adds. “Finally we have three-dimensional computer models with rotation and magnetic fields.” Another direction of their future
little with
matter, so while they may reach Earth they are very hard to detect and are only observed from comparatively nearby events using huge detectors such as the Kamiokande in Japan. The
supernovae
1987A in the large Magellanic Cloud 26 years ago was close enough that neutrinos could be observed, but with the equipment available at the time only a handful were detected. Were such an event to occur so close to Earth now, thousands more neutrinos would
be
observed. However, statistically supernovae explosions in our galaxy occur only once every 100 years and it could take several decades for the next one. “We may be lucky,” adds Professor Thielemann with a chuckle. In the meantime there is a huge amount of data to analyse and a number of puzzles
www.projectsmagazine.eu.com
research is the evolution of more massive stars. “A neutron star has a maximum mass which is 1.6 to 2 solar masses,” he explains. More material will result in further contraction and form a black hole. “The basic motivation for all this is
understanding the cosmos,” states Professor Thielemann. It seems no complexity is a deterrent to the insatiable drive of curiosity. He explains how the related observation for the exotic demise of very massive stars into black holes appears to be what people call gamma ray bursts or hypernovae. “And that is opening a completely new can of worms and making things more complicated,” he laughs. Yet despite the complications Professor
Thielemann ★ seems
undaunted. “This is the next thing,” he concludes. “The frontier we are aiming for.”
Project Duration and Timing: Astrophysical Processes: 2 years, October 2012 to September 2014 FISH: 4 years, January 2013 to September 2016
Project Funding: Astrophysical Proc.: CHF 698 000 by SNF (Swiss Nat. Sci. Found.) FISH: 1 929 075€ by ERC Advanced
Project Partners: In house senior collaborators Astrophys. Proc.: Marco Pignatari; FISH: Matthias Liebendörfer, Thomas Rauscher
Main Contact:
Friedrich-Karl Thielemann Studies: Technical University of Darmstadt (Germany) until 1976, PhD TU Darmstadt and Max Planck Institute for Astrophysics Garching 1980, Postdoc Positions at Caltech, U. of Chicago, U. of Illinois, Max Planck Institutes for Nuclear Physics and Astrophysics until 1985, Assistant and Associate Prof. Harvard Univ. (1986-1994), Full Prof. for theor. Physics at U. of Basel (since 1994). Honors/Prizes: Otto Hahn Medal of the Max Planck Soc. 1979, “Fellow” of the APS since 1998, Hans A. Bethe Prize of the APS 2008, Humboldt Research Award by Alex. von Humboldt Found. 2009, Lise Meitner Prize of EPS 2012; Associate Editor of Rev. of Mod. Phys. and Nuclear Physics A
Contact: Tel: +41 61 267 3748 Email:
f-k.thielemann@
unibas.ch Web:
www.physik.unibas.ch/dept/pages/de/ personnel/
thielemann.htm
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