Homehttps://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/Sciencehttps://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/Astronomers see strontium in the remains of Kilonova, evidence that neutron star collisions produce heavy elements in the universe
Astronomers see strontium in the remains of Kilonova, evidence that neutron star collisions produce heavy elements in the universe
Astronomers have noticed strontium as a result of a collision between two neutron stars. This is the first time a heavy element has ever been found in a kilo, the explosive consequence of these types of collisions. The discovery plugs a hole in our understanding of how heavy elements form.
In 2017, the Laser Interferometer Gravity Wave Observatory (LIGO) and the European VIRGO Observatory detected gravitational waves coming from the confluence of two neutron stars. The merger event was named GW170817 and was approximately 130 million light-years away in galaxy NGC 4993. The resulting kilo-ray is called AT2017gfo, and the European Southern Observatory (ESO) has directed several of its telescopes to monitor it. at different wavelengths. In particular, they pointed to the very large telescope (VLT) and its X-Shooter tool to kilonova.
The X-Shooter is a multi-wave spectrograph that observes ultraviolet B (UVB,) visible light and near-infrared (NIR.) Initially, the X-Shooter data suggests that there were heavier elements. But so far they have not been able to identify individual elements.
These new results are presented in a new study entitled "Identification of strontium at the confluence of two neutron stars." Lead author is Darach Watson of the University of Copenhagen in Denmark. The document was published in the journal Nature on October 24, 2019.
"By reanalyzing the 2017 merger data, we have now identified the signature of one heavy element in this fireball, strontium, proving that the collision of neutron stars creates this element in the universe, "Watson said in a press release.
Forging chemical elements is called nucleosynthesis. Scientists have known about this for decades. We know that elements are formed in supernovae, outer layers of aging stars, and ordinary stars. But there is a difference in our understanding when it comes to capturing neutrons and how heavier elements are formed. According to Watson, this finding fills the gap.
"This is the last phase of decades of pursuit to determine the origin of the elements," Watson says. "We already know that the processes that create the elements happen mostly in ordinary stars, in supernatural explosions, or in the outer layers of old stars. But until now, we didn't know the location of the final, undetected process known as fast neutron capture, which created the heavier elements in the periodic table.
There are two types of neutron capture: fast and slow. Each type of neutron capture is responsible for creating about half the elements heavier than iron. Rapid neutron capture allows the atomic nucleus to capture neutrons faster than it can decay, creating heavy elements. The process was developed decades ago, and circumstantial evidence suggests that cinema is a likely place for rapid neutron capture. But so far it has not been observed on an astrophysical object.
Stars are hot enough to produce many elements. But only the most extreme hot environments can create heavier elements like Strontium. Only these media, such as this kilo, have enough free neutrons around. In kilo atoms, they are constantly bombarded by huge numbers of neutrons, which allows the fast neutron capture process to create heavier elements.
"This is the first time we can directly relate newly created neutron capture material to a neutron star fusion, confirming that neutron stars are made of neutrons and binding the long-discussed fast neutron capture process to such mergers, "says Camilla Yul Hansen of the Max Planck Institute for Astronomy in Heidelberg, which played a major role in the study.
Although the X-Shooter data has been around for several years, astronomers were not sure they could see strontium in the kilowatt. They thought they saw him, but couldn't be sure right away. Our understanding of mergers of kilo and neutron stars is far from complete. There are complexities in the kilonova spectrum of the X-Shooter that needed to be addressed, especially as regards the identification of spectra of heavier elements.