Thermonuclear explosions on the surface of white dwarf stars are relatively frequent in the Universe and are divided between those that are more recurrent - the new classics - and the explosions that repeat over decades - the novae remnants.
A team of international researchers, including Valério Ribeiro (a researcher of the University of Aveiro and a IT collaborator), studied for the first time the results of thousands of these latest explosions in Andromeda, the galaxy closest to the Milky Way. The work has just been published in the prestigious journal Nature.
This study demonstrates that repeated explosions create a 'super-remnant' cloud larger than many remnants of supernova explosions. "This is because the various recurrent bursts that occur annually sweep the interstellar material, creating cavities in the space around the nova", explains Valério Ribeiro.
These explosions expel several chemical elements that are essential to life (hydrogen and helium in greater quantity, but also oxygen, iron, carbon, etc.) creating a cloud called the "remnant." The explosions cause the material to be distributed through the interstellar medium where new stars and planets are being formed. These clouds of chemical elements scattered by repeated explosions can reach 440 light years, 1000 million times the distance between Earth and Jupiter.
"Andromeda is an excellent laboratory for the study of novas, because in our galaxy the remnants are overshadowed by interstellar dust, which is opaque to visible light. To eliminate the problem of dust, astronomers can observe the novas through radio waves, for which the dust is transparent", says Valério Ribeiro.
Portuguese astronomers associated with ENGAGE SKA (wich is led by IT, under the coordination of Domingos Barbosa), in collaboration with a multidisciplinary team from South Africa, UK, France, the Netherlands, and others, will work with data from the forthcoming Square Kilometer Array (SKA) radio telescope, which is being built in South Africa and Australia, in order to discover all the novas in our galaxy.
Valério Ribeiro points out that the mapping of all the novas in our galaxy "helps us understand the distribution of chemical elements and how they enrich other planets in formation, creating conditions for the emergence of life-critical molecules as it has occurred with the Earth a few thousand million years ago".
Photo: This is a composite image of Liverpool Telescope data (bottom left) and Hubble Space Telescope data (top right) of the nova super-remnant. Credit: Matt Darnley / LJMU