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Astronomers have spotted something that has never been seen before. According to an article published in the newspaper ScienceA team led by researchers at the California Institute of Technology observed the unusual death of a huge star that exploded in the first "ultra-stripped supernova" recorded – a surprisingly weak supernova that faded quickly.
Supernovae are titanic explosions that occur when massive stars – at least eight times the mass of the Sun – deplete their nuclear fuel, causing the nucleus to collapse before it expands rapidly.
We usually see a lot of materials – many more times than the Sun's mass – escaping from a supernova, but the researchers found that the event in question, dubbed "iPTF 14gqr ", ejected only material equivalent to about one fifth of the mass of the sun.
"We have witnessed the collapse of the nucleus of this massive star, but we have seen a mass mass ejected remarkably low," said Mansi Kasliwal, author of the study at Caltech, in a statement. "We call this an ultra-stripped envelope supernova and have long been predicted that they exist.This is the first time that we have convincingly seen the collapse of the core of the kernel." a gigantic star devoid of matter. "
The observations indicated that the dying star had an invisible companion, perhaps a neutron star, whose strong gravitational influence siphoned off most of its mass before it exploded. as a supernova. Neutron stars are incredibly dense and compact objects that remain when massive stars throw most of their outer layers into a supernova (provided that the mass of the exploding star is not sufficient to produce a black hole).
In the case described in the last study, astronomers suggest that a previous supernova had already left a neutron star before the iPTF 14gqr produced another one, thus creating a new system. twin neutron or "binary" stars. Scientists already knew the binary neutron star systems, but it was perhaps the first time they had witnessed the birth of a system.
These twin systems – which were originally supposed to be binary systems of two massive stars – have long been a problem for scientists. Indeed, it was thought that the explosion of the second star would drive out most of the remaining mass, thus preventing the system from forming a pair in the first place.
But now, this team has proposed a new hypothesis, according to which the gravitational force of the neutron star formed during the first supernova removes most of the outer layer of the remaining star. When this "ultra-stripped" star explodes, the supernova has much less material to eject and the system can remain stable.
The 14gqr iPTF was first seen at the San Diego Palomar Observatory as part of a nightly investigation aimed at searching for transient and short-lived cosmic events, such as supernovae.
Neutron stars are among the strangest objects in the universe. Although they are very small for stars, usually between 10 and 20 miles in diameter, they tend to have a mass about 1.4 times greater than that of our Sun. According to NASA, this means that a teaspoon of a neutron star would weigh 1 billion tons.
Because of their extremely high density, they also have powerful gravitational fields. In fact, the gravitational field on the surface of a neutron star is about 200 billion times that of the Earth. Stars can also spin extremely fast, up to several hundred times a second. Some neutron stars, known as pulsars, emit intense beams of radiation, much like interstellar beacons.
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