Space Explosion, It was believed that a neutron star merger was the only way to produce heavy elements (heavier than zinc), as these mergers involve mixing the remains of two massive stars into a binary system.
We know that heavy elements were first produced not long after the Big Bang, when the universe was really young. At that time, not enough time had passed for neutron star mergers to occur. Thus, another source was needed to explain the presence of heavy elements early in the Milky Way.
The discovery of the ancient star SMSS J2003-1142 in the Milky Way’s halo – the roughly spherical region that surrounds the galaxy – provides the first evidence of another source of heavy elements, including uranium and possibly gold.
A New Type Of Space Explosion
In research by David Young, of the Australian National University’s Research School of Astronomy and Astrophysics, and Gary Da Costa, professor emeritus of astronomy, published in Nature, it was found that the heavy elements detected in SMSS J2003-1142 were likely produced, not by a neutron star fusion. But through the collapse and explosion of a rapidly rotating star with a strong magnetic field and a mass about 25 times that of the Sun.
It was recently confirmed that neutron star mergers are indeed one of the sources of heavy elements in our galaxy. As the name suggests, this happens when two neutron stars in a binary system fuse together in an energetic event called a kilonova.
Discovering A New Type Of Space Explosion
However, current models of our galaxy’s chemical evolution indicate that neutron star mergers alone cannot produce the specific patterns of elements we see in many ancient stars, including SMSS J2003-1142.
SMSS J2003-1142 was first observed in 2016 from Australia, and then again in September 2019 using a telescope at the European Southern Observatory in Chile.
From these observations, the researchers studied the chemical composition of the star. It is possible that the detected elements came from a lone star, just after the Big Bang.
The chemical composition of SMSS J2003-1142 can reveal the nature and characteristics of its parent star. Of particular interest are the unusually high amounts of nitrogen, zinc and heavy elements including europium and uranium.
High nitrogen levels in SMSS J2003-1142 indicate that the parent star had a rapid rotation, while high zinc levels indicate that the energy of the explosion was about ten times the energy of a “normal” supernova.
In the hypothesis, the only parent star made all the elements observed in SMSS J2003-1142. On the other hand, it would have taken much longer for the elements themselves to be made only through neutron star mergers. But this time it wouldn’t have existed even at this early in the galaxy’s formation when these elements were made.
The magnetic hypernovae model not only provides a better fit to the data, but can also explain the formation of SMSS J2003-1142 through a single event. And neutron star mergers, along with magnetic supernovae, could explain how all the heavy elements are created in the Milky Way. Source Science Alert