When the biggest stars in the universe die, they collapse and explode into a supernova. Some, in addition, launch a flash that lasts seconds but that contains as much energy as the one that the Sun will produce in all its life: they are outbursts of gamma rays, one of the most impressive oddities of the cosmos. An international team of scientists led by Spanish astrophysicist Benito Marcote, of the JIVE Institute (Netherlands), has discovered the remains of one of these explosions, which opens the door to new lines of study of these extreme events that are so difficult to grasp.
Astronomers think that these gamma-ray bursts occur when part of the material of the star is ejected at high velocity in the form of a jet during the explosion, but this flash is only visible if the material points directly towards the Earth, which occurs in very few occasions. After the flash, the material interacts with the gas around it and slows down and expands, producing a wrap that lasts for years. When the outbreak was not visible, it is called “orphan wrap.”
The find
The research led by Marcote and published in Astrophysical Journal Letters, has observed the trace of an explosion that took place 30 years ago and that was never observed and that, therefore, has left the remains of an “orphan” envelope. The finding was made when studying an object, FIRST J1419 + 3940, located at 300 million light years and detected in 2018 with visible light and radio waves.
This object has been attenuated for 30 years and is in an environment very similar to the only rapid burst of radio that is known with precision, mysterious events in the universe that last a thousandth of a second and that are believed to be originated by stars of neutrons or remnants of supernovas.
“Very energetic explosion”
After the discovery of this object, the scientists led by Marcote carried out radio observations with the European network of VLBI (EVN, for its acronym in English) that combines antennas spread across Europe, Asia and South Africa and that, together, allow to study an object with a resolution that would allow reading a newspaper 40 kilometers away. With this level of detail, the astronomers analyzed the object, determined that it has a size of about five light years and that the material that emits this light was thrown into space about 30 years ago at about 100 million km / h, in “a very energetic explosion.”
With all these data, the researchers conclude that the object is an orphan shell produced by a bright flash in gamma rays and that FIRST J1419 + 3940 is, therefore, the first strong evidence of this type of event. Future observations will help to understand more the evolution of this envelope and especially to determine how the material propagates and interacts with what it has around. It will also be possible to verify if gamma-ray bursts can be related to other types of events such as rapid radio bursts, which are one of the most exotic and mysterious phenomena in the universe.
