Astronomers have captured the traces of a double explosion which completed the existence of a star, providing first visual proof of this previously theoretical scenario, in a study on Wednesday.
The supernovae, these cataclysmic ends of certain stars at the end of their life, remain in many ways mysterious. Because the event, which sees the imploser star, is as sudden as they are immense.
From a mass similar to that of the sun, the white dwarfs concentrate their material in a much smaller volume. They are deemed to end their existence by turning slowly, to become black dwarfs – theorized without ever having been observed -, or by exploding in supernova.
“The explosions of white dwarfs play a critical role in astronomy,” noticed in a press release from the European Austral Observatory the doctoral student Priyam Das, the first author of the study published in Nature.
Especially because these events produce a number of elements, including iron, which will serve as a raw material to form new stars. Despite this “the long -standing puzzle of the exact mechanism triggering the explosion remains irresolved”, according to Mr. Das.
All the models agree on a scenario where the white dwarf accumulates matter by stealing it from a twin star, until imploding under its own mass.
But recent studies have pointed out towards a second possibility, in which the white dwarf is dragging itself in a helium blanket stolen from its partner, and which “can become unstable and detonate”, according to the press release. The shock wave of this blast would then compress the white dwarf, which would in turn explode in supernova.
Thanks to the Muse instrument installed on the very large telescope of the European Austral Observatory (ESO) in Chile, the team of astronomers has captured a “photographic instant” of the remains of the event, baptized SNR 0509, and occurred about 300 to 330 years ago in the Magellan cloud, close to the Milky Way.
In accordance with theory, these images show two distinct rings of calcium, colored in blue in the images of Muse, each corresponding to an explosion.
It is a “clear indication” of what the “mechanism of + double detonation + takes place in nature”, according to the astronomer Ivo Seitenzahl, of the German Institute of Heidelberg for theoretical studies, which led observations.
Posted on July 2 at 12:22 p.m.
