The universe still holds many secrets that human beings have not been able to reveal; among them, one that catches us very closely: how did our solar system come about? Of course, there are theories that try to answer this question, and the most established among them explains that our cosmic environment had its origin, billions of years ago, in a supernova .
However, a team of researchers from the University of Chicago (USA) has just proposed an alternative theory. According to the new scenario proposed by their study, recently published in the Astrophysical Journal , our solar system would have emerged in a bubble driven by the wind around a giant star, long dead .
This star belongs to a type called Wolf-Rayet , with a size between forty and fifty times that of our Sun, hot – with surface temperatures of between 25,000 and 50,000 degrees Kelvin – and which suffers large mass losses that are thrown out. from the surface due to the violence of the intense stellar winds. And as the Wolf-Rayet star expels those tons of elements from its surface, the stellar wind injects that material that was around it into bubble structures that have a higher density coating.
“The shell of such a bubble is a good place to produce stars,” since dust and gas are trapped inside, where they can condense into stars , according to study co-author Nicolas Dauphas, a professor in the Department of Geophysical Sciences.
Explain the origin of other similar stars
Following this hypothesis, the authors of the research consider that between 1% and 16% of all stars that are similar to the Sun could have been formed in “stellar nurseries” – as they have been called – of this class.
The new configuration proposed by the University of Chicago differs from the supernova hypothesis to make sense of two isotopes that appear in different proportions in our solar system compared to the rest of the galaxy .
On the one hand, the remaining meteorites from the early solar system tell us that there was a lot of aluminum-26; And studies, including one by Dauphas himself dating from 2015, increasingly suggest that there was less iron-60 isotope. Something that is puzzling for scientists, since supernovae produce both elements in large quantities.
“This raises the question of why one was injected into the solar system and the other was not,” explains Vikram Dwarkadas, co-author and research associate professor in Astronomy and Astrophysics. And this idea led them straight to the Wolf-Rayet stars, which launch large amounts of aluminum-26, but not iron-60 .
And what happened to that giant star? It would have died a long time ago, and very possibly its days would have come to an end as a supernova or collapsing into a black hole , which barely emits iron-60.
Image: courtesy of V. Dwarkadas and D. Rosenberg
‘Triggered star formation inside the shell of a Wolf-Rayet bubble as the origin of the solar system’. The Astrophysical Journal, Dec. 22, 2017. DOI: 10.3847 / 1538-4357 / aa992e.
