An international collaboration of researchers, including the Konkoly Thege Miklós Astronomy Institute of the HUN-REN Astronomy and Earth Science Research Center (CSFK) and the astrophysicists of the University of Szeged, measured the time scale of the birth of the Sun.
According to their results, the Sun turned into a star relatively quickly, in 10-20 million years, from the gaseous material of its formation area, and was not born alone, but in a large family of stars.
During the investigation, the researchers first measured the decay of fully ionized thallium ions using the special particle accelerator of the GSI/FAIR laboratory in Germany, and then, based on the results of the experiment, they were able to calculate how much radioactive lead (205Pb) is produced inside the stars. Based on the amount of radioactive lead produced, the researchers determined a value between 10-20 million years for the time scale of the formation of the Sun from the parent gas material – read the statement of the HUN-REN CSFK on Wednesday.
The researchers published their results on Wednesday in the journal Nature.
Astronomers can study the time scale of the formation of the Sun by using the decay of long-lived, radioactive nuclei that were formed in other stars before the birth of the Sun as a “clock” for the formation of the Sun from the parent molecular cloud.
In the 4.6 billion years since the birth of the Sun, these radioactive nuclei have already decayed, but they have left their mark in the decay products that can be detected in meteorites.
The ideal subject for conducting the study is radioactive lead (205Pb), the only radioactive nucleus that can only be produced in medium-mass stars, approximately two to four times more massive than the Sun, through neutron capture.
On Earth, radioactive lead (205Pb) atoms decay into 205Tl (thallium) atoms by capturing an atomic electron, which converts one of their protons into a neutron. In stars, where the temperature is much higher (up to hundreds of millions of degrees Celsius) and all the electrons have been stripped from the atoms, the reverse process can also take place: 205Tl decays into 205Pb. This is an exceptionally rare decay mode.
“Due to the complex behavior of the two nuclei, we can only estimate the amount of radioactive lead produced in stars if we know how the rate of decay of the two nuclei changes with the temperature inside the star. The problem is that these decays cannot be measured under normal laboratory conditions, as thallium is stable on Earth,” the researchers explain.
To overcome this obstacle, a group of researchers from 37 institutions in 12 countries measured the decay of fully ionized thallium ions using a special particle accelerator at the GSI/FAIR laboratory in Germany. To do this, thallium had to be stripped of all its electrons and kept in this special state for several hours.
The work was then taken over by astrophysicists, including researchers from the HUN-REN CSFK Institute of Astronomy and the University of Szeged, who estimated how much radioactive lead is ejected from medium-mass stars by calculating new star models.
“The precise values of the decay rates allow us to estimate with great certainty how much radioactive lead (205Pb) was produced in the stars and reached the parent gas cloud of our Sun,” explained Balázs Szányi, a student at the Doctoral School of Physics at the University of Szeged.
“Compared with the amount of radioactive lead that can be derived from meteorites, we determined that the Sun turned into a star relatively quickly, within 10-20 million years, from the gaseous material of its formation area. This is consistent with other radioactive nuclei produced in the same stars. This means that our Sun was not born alone, but in a large family of stars, together with many of its siblings, which dispersed and lost each other a long time ago,” Maria Lugaro, a researcher at the Institute of Astronomy, summarized in the announcement.
“The ground-breaking experimental equipment, the interdisciplinary cooperation of the world’s nuclear physics and astrophysics research groups and a lot of hard work can help us understand the nuclear processes inside stars. Our new experiment revealed the time scale of the events 4.6 billion years ago that led to the formation of our Sun,” highlights Guy Leckenby, PhD student at the Canadian National Particle Accelerator Center (TRIUMF) and first author of the publication.
The researchers dedicate their work to the memory of their deceased colleagues, Fritz Bosch, Roberto Gallino, Hans Geissel, Paul Kienle, Fritz Nolden, and Gerald J. Wasserburg, who supported this research for several decades, the announcement states.
Source: magyarnemzet.hu
