The extremely rare system in question is doomed to explode in a fiery kilonova caused by the merger of two high-mass neutron stars, themselves descendants of an ultra-depleted supernova.
Astronomers at the US National Research Laboratory for Optical-Infrared Astronomy (NOIRLab) have discovered the first X-ray binary star system that has all the right conditions to eventually trigger a kilonova. Such a system is so extremely rare that only about 10 of them are thought to exist in the entire Milky Way.. The ultra-powerful explosion of a kilonova, created by the collision of neutron stars, would produce gold and other heavy elements, they reported on Wednesday.
ultra stripped supernovae
This unusual system, which has been named CPD-29 2176, is located about 11,400 light-years from Earth. Observations with the 1.5-meter SMARTS telescope from the Cerro Tololo Inter-American Observatory in Chile allowed astronomers to deduce that the system is composed of a neutron star, created by an ultranaked supernova, and a massive star in a close orbitwhich is in turn in the process of also becoming an ultra-stripped supernova.
Ultra-stripped supernovae are the result of the explosion of a massive star in a binary system, which has had much of its atmosphere stripped away by a companion star. This class of supernova lacks the explosive force of a traditional one, which would otherwise “expel” its nearby binary star from the system.
“The current neutron star would have to form without ejecting its companion from the system. An ultranaked supernova is the best explanation for why these companion stars are in such a tight orbit,” said Noel D. Richardson of Embryo Aeronautical University. Riddle (USA) and lead author of the study. “To create a kilonova one day, the other star would also have to explode, as an ultra-naked supernova, so that the two neutron stars could collide and merge“, he explained.
An incredibly rare discovery
“We know that the Milky Way contains at least 100 billion stars, and probably hundreds of billions more. This remarkable binary system is essentially a one in 10 billion system,” said NOIRLab astronomer Andre-Nicolas Chene and co-author. of the study. Finding and studying parent systems like this one can help scientists unravel the mystery of how kilonovae form, shedding light on the origin of the heaviest elements in the Universe.
lots of gold and silver
Although this system has what it takes to eventually form a kilonova, the other massive star in the pair will take at least a million years to explode, in titanic supernova fashion, and become the second neutron star. The pair of neutron stars will need to coalesce gradually, as both slowly lose their orbital energy as gravitational radiation. When they eventually merge, the kilonova explosion will produce much more powerful gravitational waves and will leave behind a large amount of heavy items, including silver and gold.
“As we understand the growing population of systems like CPD-29 2176, we will gain insight into how quiet some stellar deaths can be and see if these stars can die without traditional supernovae,” Richardson concluded. The findings were published last Wednesday in Nature.
Source: RT
