NASA/CXC/Meiji Univ./T. Sato et al.
Chandra’s new observations reveal how Cassiopeia violates her violently to her interior just a few hours before exploding. In the expanded box, red is rich in silicon, while blue is rich in neon.
A team of scientists who resorted to the X-ray Telescope Chandra revealed new details about the remains of the famous Supernova Cassiopeia A.
About 11,300 years ago, a massive star was on the verge of destruction. He pulsed with energy as he freed his outer layers into space until he exploded as Supernova.
What remains of this explosion, Cassiopeia A (CAS A), is today one of the most studied supernova remnants. Now, Chandra’s new observations are unraveling unpublished details about their collapse.
The Progenitora of Cas Star would have it between 15 and 20 solar massesand may have even arrived at 30, according to some estimates.
It is likely to be a supergent redalthough there is debate as to its nature and the path that led to the explosion. Other astrophysicists suggest that It could have been a wolf-rayet star.
In any case, The star exploded like a supernova collapse of the core. When forming a iron corehe could no longer sustain himself, collapse and originating the explosion.
The light of this death arrived on Earth around the 1660s. There are no unequivocal historical records of observer who have seen the phenomenon in the sky, but modern astronomers have studied in detail and in various wavelengths.
A new one, published last week in the magazine The Astrophysical Journal It now realizes Chandra’s latest discoveries.
“It seems that each time we closely analyze Chandra’s data on Cas a, we learned something new and exciting,” he said Toshiki Satoresearcher at the University of Meiji, in Japan, and the main author of the article at the University.
“Now we combine this precious X-ray data with advanced computational models and We found something extraordinary”Adds the investigator.
One of the great challenges in the study of supernovae is that we only have access to observations after the explosion. Getting details about the final moments before the star’s death is extremely difficult.
“Theorists have given particular attention to FINAL INTERNAL PROCESSES From massive stars, as they can be essential to understanding the mechanisms of supernovae driven by neutrinos and other phenomena associated with stellar collapse, ”the authors explain in the article.
“However, It is almost impossible to directly observe the last hours Of life of a massive star, as it is the explosion that triggers observational attention, ”says Sato.
As a massive star approaches the end, its core is synthesizing increasingly heavy elements: First hydrogen, then Helium, carbon and others. In the end, it generates iron – but it is a blockadebecause its fusion does not release energy, it consumes.
When the iron core reaches about 1.4 solar masses, the pressure to counteract gravity is no longer sufficient. Or collapse nucleus and the star explodes.
Chandra’s observations, combined with modeling, are offering astrophysicists a unique view of the interior of the star in the final moments before collapse.
“Our investigation shows that, shortly before the collapse of the star in Cas a, part of an internal layer rich in silicon moved out and invaded an abundant neighboring layer in neon, ”he explained Kai MatsunagaCo -author of the study and researcher at the University of Kyoto. “It was a violent event where the barrier between the two layers disappeared. ”
The result was double: Silicon moved abroad, while the neon was dragged inside. This process generated an unequal mix of the elements, with small silicon -rich regions coexisting with others rich in neon.
Scientists describe this phenomenon as a “layer fusion”-The last phase of stellar activity. It is an intense combustion, where the oxygen layer absorbs the outer layers of carbon and neon, already in the depths of the star. This happens only moments before the explosion.
“In the conventive violent layer created by this fusion, the neon, abundant in the oxygen -rich zone, It is consumed when pulled inwardwhile silicon, sintent in the countryside, is transported out, ”detail the investigators.
The intertwined regions of silicon and neon They are the first observational test of this process. Astrophysical models already predicted him, but had never been registered before. “Our results show that the final combustion rapidly alters the star’s internal structure, Leaving asymmetries before the explosion”They explain.
For decades, It was thought that the supernovae were symmetrical. The first observations and theoretical models pointed to this.
This new work, however, challenges this vision And suggests that the explosions of supernovae They are, after all, asymmetrical. This asymmetry may also explain how the resulting neutral stars receive an impulse that throws them at high speeds.
According to the authors, the turbulence generated inside the star In the final moments you may have helped to trigger the explosion.
“Perhaps the most important effect of this change in the star’s structure is that it may have contributed to the explosion itself,” he said Hiroyuki Uchidaalso from the University of Kyoto. “The final internal activity of a star can determine its destination – will shine as supernova or not”.
“For a long time, It was a dream of astronomy cOnce the internal structure of the stars, the researchers under the conclusion stress. This study offers, for the first time, a fundamental glimpse of these last moments.
“This moment not only deeply marks the destination of the star, but also gives rise to a more asymmetrical explosion,” they conclude.
