According to a team of astronomers reporting in the journal Nature, super-luminous supernovae are powered by small and incredibly dense neutron stars, with gigantic magnetic fields that spin hundreds of times a second.
High-resolution simulation of a galaxy hosting a super-luminous supernova. Image credit: Adrian Malec / Marie Martig / Swinburne University.
The origins of super-luminous supernovae are not well understood. Current theories suggest that these rarest and brightest stellar explosions occur when extremely massive stars undergo a nuclear explosion triggered by the conversion of photons into electron-positron pairs. This process is completely different compared to all other kinds of supernovae.
To dig deeper into the origins of this rare class of supernovae, the astronomers using the world’s largest digital camera at the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) on Mount Haleakala in Hawaii have observed two super-luminous supernovae.
The results suggest that their origins may be better explained by a type of explosion within the star’s core which creates a smaller but extremely dense and rapidly spinning magnetic star.
“Supernovae are several billions of times brighter than the Sun, and in fact are so bright that amateur astronomers regularly search for new ones in nearby galaxies. It has been known for decades that the heat and light from these supernovae come from powerful blast-waves and radioactive material,” said lead author Matt Nicholl, a research student from Queen’s University Belfast.
“In a supernova explosion, the star’s outer layers are violently ejected, while its core collapses to form an extremely dense neutron star – weighing as much as the Sun but only tens of km across.”
“We think that, in a small number of cases, the neutron star has a very strong magnetic field, and spins incredibly quickly – about 300 times a second. As it slows down, it could transmit the spin energy into the supernova, via magnetism, making it much brighter than normal. The data we have seems to match that prediction almost exactly.”
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Bibliographic information: Matt Nicholl et al. Slowly fading super-luminous supernovae that are not pair-instability supernovae. Nature 502, pp. 346–349; doi: 10.1038/nature12569
