Red Super giants do not always ends in supernova.

 In 2008, a giant red star appeared on the horizon of its life. A heavy star like this is born 25 times the mass of the Sun, had to come out with a boom of firelight known as a supernova, millions or billions of times brighter than our Sun. But this star refused to play the role of the drama queen. Instead, it just emits a little light, then disappeared, perhaps leaving a black hole.

No one has ever seen one of these huge red stars dying quietly in the past. It was a sign that the lives and death of these stars are even more complicated than our simple ideas. "As amazing and important and fun and exciting as this is, it's not surprising," said Stan Woosley at the University of California, Santa Cruz. In fact, the discovery may be helpful in explaining why big stars in computer models often fail to explode.

A popular theory holds that almost all stars born more than eight times the size of the Sun ends up in supernovae. When the star is young, it shines brightly and blue. A nuclear reaction in its sphere produces great power. This keeps the star so hot that gas pressure pushes out and partially opposes the internal gravity of the star's gravitational pull; as well as the pressure of multiple photons emanating from the core of the star. As long as it produces energy, the star can hold on.

But in the end, gravity wins. Later in life, as the big star begins to run out of fuel, it expands. Stars born between 8 and 25 or 30 solar masses grew so numerous that their surface cool, and the stars became red supergiant. If the Sun were equal to that the biggest red supergiant, would cover every planet from Mercury to Jupiter. After that, according to typical learning, a star consumes its fuel and its core collapses. The fall triggers a wave of neutrinos. These ghost particles often pass uninterrupted on the subject, but the fall of the core produces so many neutrinos that they explode the outer surface of the star layers, launching the titanic supernova explosion.

Indeed, astronomers see many supernova explosions in other galaxies, usually in orbits the big stars remain. So common belief has always been that almost all stars are born over eight days the masses explode like supernovae. But for decades, scholars like Woosley have struggled to make these big stars explode inside computer models; instead, model stars often fall under their own weight. Investigators often think of Shakespeare's famous words it sounds true here: The fault is not in our stars, but in us. Types of theory may not mimic the worst situations in these worst stars.

But in recent years, recognition has begun again to suggest that some red supergiants do not actually go supernova. Since 1987, when viewers saw the supernova in the Large Magellanic Cloud, a neighbouring galaxy, astronomers have been able to explore the newly exploded images of galaxies again which star exploded.

As expected, most of the doomed stars were great red supergiants. But do not replace the full range of mass from eight to 30 days. "We have there is almost no stargazing over the [birth] mass of 17 solar masses, "says Smartt, "and this should be bright, easy to find in photos."  He calls this failure a red supergiant problem.

That disappearing supergiant of 2008 is possible for example, Smartt says. The star's home is an inexhaustible galaxy of 25 million light-years from Earth named NGC 6946, famous for its numerous supernovae. From 1917 to 2017 astronomers saw 10 supernova explosions there, more than any other galaxy; but the supernova did not occur it may seem more important than all that happened.

No one saw the star disappear from time. In 2014, however, Christopher Kochanek and graduate Jill Gerke, both at Ohio State University in Columbus, was studying photography near the Milky Way so that they can see the stars more clearly. These astronomers knew about the red supergiant and the problem and trouble the theorists had in their discovery of exploding stars. Pictures of galaxies have taken a million red supergiants, each possible future supernova. By comparing images of different ages, astronomers hoped to capture the exact opposite: the red supergiant fell out of sight as it became a black hole.

In 2019, Tuguldur Sukhbold at Ohio State University has suggested an explanation for the explosion of large red supergiants at the lowest and highest masses: “The end depends on how carbon burns in a big star, ”he said. His work builds on the adoption of a quarter of years ago that carbon burns differently depending on the big star was born at least or less than a certain weight.

For most of its life, the giant star converts hydrogen into helium in its core, as does the Sun. When hydrogen runs out, helium burns, creating carbon and oxygen. And when the helium runs out, the star, desperately trying to hold on to its heavyweight, hits it carbon, converting it into neon, sodium, and magnesium.

But carbon comes with a catch. It burns at such high temperatures that the intense heat generates photons, which is converted into pairs of electrons and antielectrons. These tend to end one another and can also produce neutrinos and antineutrinos, emanate from the star, deprive them of energy, and do nothing to oppose it against gravity. Due to neutrino loss, as long as the carbon burns, the star does not have more than a few thousand years of life. Then the star heavy fuel burns until it run out out of all its gases (i.e. hydrogen and helium). The final reaction forms iron, which means death, e.g. the star will no longer be able to combine nuclear energy from the most stable nuclei. With nothing to support, the core collapses.

But whether the star explodes or falls really depends on how you burn its carbon in its core. In large red supergiants, carbon is not burned in a typical way; this reduces neutrino loss and it leads to a more extended core with the dense material around it. When the core falls,  the blast wave hits a thick dense materials above, which prevents explosion. Instead of building a supernova, a star ends up forming a black hole.

This new thinking does not change our perception of the lives and deaths of big stars but also statistics

on how they born in their galaxies with new chemical elements. From the giant stars, neutrons slowly alter the nuclei of the metal with the star was born into heavy materials like yttrium and zirconium. But if the stars never explode, these elements fall into the black hole, depriving the galaxies of the full chemical properties of the stars.