One of the bulky stars ever identified today, the WOH G64 It may be undergoing “a sudden but smooth change in its nature,” says one study.
This change of extreme red supergent, which is part of the great cloud of Magalhães (LMC), seems to have occurred in just a few years, which represents a fraction of the second in cosmic terms and indicates that the object with a radius of 1.54 thousand times the sun can explode in a supernova.
Conversion to Supernova, which develops in a dramatic sequence of events, can be visible from the earth as an extremely bright point in the LMC satellite galaxy, even at a distance of about 160,000 light years.
This type of explosion of a massive star occurs when its core collapses over itself after becoming iron. The phenomenon happens in the blink of an eye, reaching approximately 23% of light speed .
The core fall matter comes to extreme densities, creating a shock wave that propagates out, but usually loses energy and stagna. However, it releases a huge mass of neutrinos, elementary subatomic particles that deposit energy in the outer layers of the collapsed core.
In this process, they end up reenergizing the shock wave and enable the explosion of the external layers of the star. The resulting brightness increases rapidly and can temporarily overcome the brightness of an entire galaxy.
The sudden change of star Woh G64
Located about 160,000 light years from Earth, WOH G64 was originally cataloged in 1981, at the Great Cloud of Magalhães, a collision galaxy with our Milky Way. The star is one of the largest known red supergigants that exhausted the hydrogen from the nucleus.
It was believed that it had 1,500 times the size of the sun and had an instability that caused the faster loss of mass already seen to this day. With data from the VLT and Magellan telescopes in Chile, astronomers discovered the surprising cause of this turbulent behavior.
A spectral analysis (study of light) showed that the star underwent a drastic change: its temperature: it rose from 3,000 ° C to almost 4,500 ° C, which changed both visible chemical composition and its color, which went from characteristic red to more bluish tones.
The transformation was so significant that co -author Alceste Bonanos, from the National Observatory of Athens, in Greece, He thought he was watching a wrong star . “This was the first clue that something was happening,” she said in a statement.
Since there were no continuous observations of the star, it is not yet possible to know accurately when the transition occurred. But there is evidence that it happened in a very short astronomically of just a few years.
The star has undergone two drastic changes: first, a reduction because it now has about half the size it had before. There was also a decrease in luminosity: its red light is currently about 1% of the original shine
Is WOH G64 about to become a supernova?
The authors observed the transformation of WOH G64, from red supergent into yellow hypergigging, between 2009 and 2016. Although already theorized, Metamorphosis had never been documented in real time .
To explain the changes observed in the hypergicient, the researchers have two theories. In the first of these, they propose that the stellar wind, a particle flow that comes out of its own star, may have expelled its outer layers into space, leaving it dangerously unstable.
In the second scenario, the external layers of the star may have been removed due to an interaction with another cosmic giant. This hypothesis implies that Woh G64 is part of a binary system (two stars that orbiting each other).
Leader of the first team to capture the image of a star in another galaxy, Jacco Van Loon of the University of Keele explains: “We knew that Woh G64’s behavior was unsustainable by the high rate of mass loss, but we did not expected to witness this transformation into our time.”
Roberta Humphreys, who, like Van Loon, did not participate in the current study, suggests a curious alternative. For star astrophysics at the University of Minesota, USA, WOH G64 has always been a yellow hypergicient, but appeared to be a red supergent so far.
The truth is that, red or yellow, the evolutionary nature of Woh G64 continues to generate heated debates in the scientific environment. “We need to question: What exactly is the evolutionary state of this star? Is it close to becoming a supernova?” Asks Humphreys to New Scientist.
During next year, the Bonanos team will continue to regularly monitor WOH G64, with the VLT telescope. After all, this is a unique opportunity to observe and document the final stages of the life of a massive star .
The study is in the peer review phase in Nature Portfolio.
This content was originally published in Estrela 1,500 times larger than the sun has rapid metamorphosis and can explode on the CNN Brazil website.
Source: CNN Brasil
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