The magnificent Whirlpool Galaxy, just 23 million light years from us in the Canes Venatici constellation, normally as calm as it is beautiful, was the scene of the supernova, one of the most violent events in the Universe. Combining telescopes from Spain, Sweden, Germany, and Finland, and processing their signals with a supercomputer at JIVE in Dwingeloo, astronomers synthesized a telescope as large as the whole of Europe. This enabled them to obtain an image with a resolution 100x sharper than what the Hubble Space Telescope can produce. The technique, known as Very Long Baseline Interferometry (VLBI) allowed Iván Martí and collaborators to take a 'radio picture' of supernova SN2011dh a couple of weeks after explosion.
These observations are record-breaking. “This is the earliest high-resolution image of a supernova explosion ever obtained. The image allows us to constrain the expansion speed of the shock generated in the explosion”, says Iván Martí from the Max Planck Institute for Radio Astronomy in Germany, who led the observations. Valeriu Tudose from ASTRON adds, “With the obtained precision we can locate the progenitor star in the existing sky catalogs prior to the explosion, and also better calibrate oncoming observations.”
Supernovae are cataclysmic explosions which terminate the lives of massive stars in a violent and spectacular way. They are bright at optical and ultra-violet wavelengths, but only a handful are detected in the radio band. Michael Garrett, director at ASTRON, adds: “If we are so lucky, as in this case, we can sharply image supernovae with the best resolution available in astronomy, provided by the VLBI technique”. The VLBI technique used for these observations takes advantage of cutting-edge technology developed at JIVE and ASTRON, both in Dwingeloo. The international team of astronomers is working on the analysis of new observations of this supernova.
The Whirlpool Galaxy and the Supernova SN2001dh on June 14, 2011, two weeks after explosion. The zoom shows the radio image of the young supernova with a resolution factor of 50000x compared to the optical. © Optical image (large): Rod Pommier 2011, Pommier Observatory, Portland, OR, USA. Radio image (subpanel): I. Martí-Vidal and collaborators, Astronomy & Astrophysics, 2011.
The team members are:
I. Martí-Vidal (MPIfR), V. Tudose (ASTRON), Z. Paragi (JIVE), J. Yang (JIVE), J.M. Marcaide (Valencia), J.C. Guirado (Valencia), E. Ros (Valencia), A. Alberdi (IAA), M.A. Perez-Torres (IAA), M.K. Argo (ASTRON), A.J. van der Horst (Amsterdam), M.A. Garrett (ASTRON), C.J. Stockdale (Marquette), K.W. Weiler (NRL).
The European VLBI Network is a joint facility of European, Chinese, South African and other radio astronomy institutes funded by their national research councils.