Supernova core containing silicon and sulfur discovered

An international research team led by scientists from the Weizmann Institute of Science (Israel) and Northwestern University (USA) has discovered that the core of a supernova - a giant star that explodes - contains many heavy elements such as silicon, sulfur and argon.

This is the first time scientists have directly observed this structure before the explosion took place.

The star, named SN2021yfj, suddenly lost its outer layers, revealing a blazing core at the centre - thought to be the star's "heart" - before exploding.

"We now have evidence that heavy elements exist inside stars," said Professor Avishay Gal-Yam, head of the experimental astrophysics group at the Weizmann Institute. "We knew the Sun was mostly hydrogen and had hypothesized that stars contained heavier elements. But this is the first time we have shown it."

In addition to Professor Gal-Yam, the research involved Dr. Ofer Yaron, a leading expert on supernova databases at the Weizmann Institute, and Dr. Steve Schulze, the paper's lead author, now a researcher at Northwestern University (formerly a member of Gal-Yam's team). The research team also included scientists from France, Italy, China and Ireland.

The star SN2021yfj was first discovered in September 2021 using the Zwicky Transient Facility in California, using a wide-angle camera to scan the entire night sky.

Dr. Schulze discovered an unusual flash of light in a star-forming region 2.2 billion light years from Earth.

Wanting to determine the elemental composition, the team sought to collect light spectra - a technique for analyzing light to determine the elements present in the explosion.

However, due to weather conditions and a lack of suitable observing equipment, it took some time for the team to obtain spectral data from a colleague at the University of California, Berkeley.

Immediately after receiving the data, Professor Gal-Yam identified the presence of silicon, sulfur and argon - something that had never been recorded before.

Typically, a supernova forms when a massive star nearing the end of its life collapses under its own gravity, causing a powerful explosion and emitting light that lasts for weeks.

Previously, "stripped" stars were often observed to reveal only helium or carbon and oxygen layers after losing their outer hydrogen shells.

However, SN2021yfj has lost more layers, allowing scientists to peer deeper into the core and detect heavier elements never recorded before the explosion.

"This star has lost most of the material it created during its lifetime," said Dr Schulze. "We can only see material that was formed in the months before it exploded. There must have been some kind of violent event."

Scientists theorize that the supernova explosion may have been influenced by a companion star, a pre-supernova eruption, or even unusually powerful stellar winds.

"Looking deep into the core of a giant star expands our scientific understanding of the origin of heavy elements," Professor Gal-Yam stressed. "Every atom in our bodies and in the world around us was formed somewhere in the universe. They underwent countless transformations over billions of years before they arrived here, so tracing their origin and the process of their formation is a huge challenge."

Professor Gal-Yam's research team said it will continue to pursue research to discover more about how elements form in the universe./.

Source: https://www.vietnamplus.vn/phat-hien-loi-sieu-tan-tinh-chua-silic-va-luu-huynh-post1056999.vnp