What color does a star turn when it dies?
Most stars take millions of years to die. When a star like the Sun has burned all of its hydrogen fuel, it expands to become a red giant.
The color of a star is linked to its surface temperature. The hotter the star, the shorter the wavelength of light it will emit. The hottest ones are blue or blue-white, which are shorter wavelengths of light.
After the star's outer layer has escaped, the much smaller inner layer collapses into a white dwarf. This star, which is hotter and brighter than the red giant it came from, illuminates and warms the escaped gas, until the gas starts glowing by itself – and we see a planetary nebula.
Once there is no fuel left, the star collapses and the outer layers explode as a 'supernova'. What's left over after a supernova explosion is a 'neutron star' – the collapsed core of the star – or, if there's sufficient mass, a black hole.
Superluminous supernova marks the death of a star at cosmic high noon.
Some swell into red giants, blow away their outer layers, and then fade away. That process, though, takes tens of millions of years to complete at least—again, far longer than the time it takes light to reach us. Lower-mass stars don't even do this. They just fade over time, lasting hundreds of billions of years.
Young stars appear blue and old stars appear red because the young stars are hotter than the old stars. The hot stars emit more energy and appear blue, old star emits less energy and appear red.
This is because information about the color of stars is very useful to astronomers and gives them information about the surface temperature of a star. The surface temperature of a star determines the color of light it emits. Blue stars are hotter than yellow stars, which are hotter than red stars.
Blue Period
Luminous blue variable (LBV) stars are indeed incredibly rare; astronomers have only identified about 20 (maybe) and suspect there are only a few hundred in the Milky Way, tops.
One Star's End is a Black Hole's Beginning
Most black holes form from the remnants of a large star that dies in a supernova explosion. (Smaller stars become dense neutron stars, which are not massive enough to trap light.)
What is a dead star?
A white dwarf is what remains of a star like our Sun after it sheds its outer layers and stops burning fuel though nuclear fusion.
As the core runs out of hydrogen, the star starts to briefly burn helium. This causes the surface layers to be pushed out and the star is now known as a red giant.

Every star we can see is almost certainly still alive, dispelling one of astronomy's most popular myths. Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words.
Although nuclear burning of hydrogen and helium had ceased in its core, causing it to collapse under its own weight, some of the star's outer layers became so dense that fusion of helium resumed there. It came back to life.
The upper layers will expand and eject material that will collect around the dying star to form a planetary nebula. Finally, the core will cool into a white dwarf and then eventually into a black dwarf. This entire process will take a few billion years.
The most massive stars live for a cosmically brief hundreds of millions of years. They live fast and die young. The smallest stars that are less than about 10% of the sun's mass have far less fuel to begin with; even so, they can eke out a living from their fuel supply for hundreds of billions of years.
These stars are most probably around 15 billion years old, but they could conceivably be as young as 12 billion years or as old as 18 billion years. It is very unlikely that most of them could be either younger or older than this range.
Star sapphires and star rubies are the rarest and most valuable stones of their type.
A blue supergiant (BSG) is a hot, luminous star, often referred to as an OB supergiant. They have luminosity class I and spectral class B9 or earlier. Blue supergiants are found towards the top left of the Hertzsprung–Russell diagram, above and to the right of the main sequence.
As stars age, they run out of hydrogen to burn, decreasing the amount of energy they emit. Thus, younger stars can appear bluer while older ones appear more red, and in this way, a star's color can tell us something about that star's age.
How long do blue stars last?
In exchange for their tremendous size and energy, blue supernovas have short lifespans. They only live around 10 million years, which sounds like a long time ... until you realize the sun can live to be 10 billion. While they're alive, blue supergiants produce a tremendous amount of energy within themselves.
A blue star survives on average only 15 to 20 million years. They go giant after eight million years after having already burned through all the hydrogen it has. Blue stars die out 1000 times faster than even a yellow star like our Sun, let alone a red star!
There are still stars capable of producing them, like the Wolf-Rayet blue giants and supergiants, and white dwarves and post-AGB stars. Even O-class stars can produce copious amounts of such radiation. Just they are quite rare, or (in the case of white dwarves), quite dim.
Green and purple stars do exist. The color of stars depends on their temperatures, and they emit radiation throughout the visible spectrum. But when a star emits peak radiation at a wavelength we define as green, it also emits radiation over the rest of the spectrum.
The energy of the blue star is therefore more than the energy of the Sun (since it is inversely proportional). Therefore, the temperature of the star will be greater than the temperature of the Sun, i.e., the star which appears blue will be much hotter than the Sun.
We Can See Protoplanetary Disks
Also, there appears to be a very young star that has formed out of the remnants of Supernova 1987A, making it the youngest star we've yet seen.
"Earendel" was spotted about 900 million years after the universe was born, making it by far the most distant star ever seen.
The overwhelming majority of the Universe will not be consumed by black holes, but rather flung into intergalactic space. Once there, they will wander the Universe as "runaway stars" (or stellar remnants) for as long as the Universe still exists.
No. While none exist to date it would be possible for a dead star to have cooled to a safe temperature. However, such objects are inherently supported by degeneracy pressure--they're very dense.
Brooks Peck, a curator at the EMP Museum in Seattle believes that creating enough metal to build the Death Star is also theoretically possible—but only if we already have an established space infrastructure to support it. We technically do, but it's still in its infancy.
Is the Moon A dead star?
There is no life on the Moon, for example, there is no air for a living being to breathe. We can see the Moon in the sky (especially at night) because it is illuminated by sunlight. The Moon is a secondary planet because it revolves around a larger planet, Earth.
But as a star burns through its fuel and begins to cool, the outward forces of pressure drop. When the pressure drops low enough in a massive star, gravity suddenly takes over and the star collapses in just seconds. This collapse produces the explosion we call a supernova.
Massive stars transform into supernovae, neutron stars and black holes while average stars like the sun, end life as a white dwarf surrounded by a disappearing planetary nebula.
As these stars churn hydrogen into helium in their cores, they constantly replenish their hydrogen stores from the surrounding disk. As a result, they never run out of fuel, never leave the main sequence, and never die.
We estimate at about 100 billion the number of galaxies in the observable Universe, therefore there are about 100 billion stars being born and dying each year, which corresponds to about 275 million per day, in the whole observable Universe.
What has happened to the stars? Of course they're still there, but we can't see them because of light pollution: the excessive and misdirected anthropogenic and artificial light that has invaded our night skies. Stars have helped shaped human culture for thousands of years.
As the cloud collapses, the material at the center begins to heat up. Known as a protostar, it is this hot core at the heart of the collapsing cloud that will one day become a star.
One Star's End is a Black Hole's Beginning
Most black holes form from the remnants of a large star that dies in a supernova explosion. (Smaller stars become dense neutron stars, which are not massive enough to trap light.)
Green and purple stars do exist. The color of stars depends on their temperatures, and they emit radiation throughout the visible spectrum.
A star's color tells us about its temperature and mass, and blue stars are the hottest and most massive of all. Any star that has three or more times as much mass as the sun will tend to look blue to our eyes.
When a star dies does it get brighter?
Yes. A star like the Sun spends about 10 billion years on the main sequence. During that time, it gradually gets brighter. After that, when it's running out of hydrogen fuel in its core, it swells into a much brighter red giant star for a relatively brief time before dying.
When stars die, they become either black holes, neutron stars, or white dwarfs.
There are no classes of object in our Universe more extreme than black holes. With so much mass present in such a tiny volume of space, they create a region around them where the curvature of space is so strong that nothing — not even light — can escape from its gravity once a certain boundary is crossed.
As the remains of the star get pulled in, it releases blips of light about every 200 seconds, with occasional lags. "You can think of it as hearing the star scream as it gets devoured, if you like," Jon Miller, a University of Michigan astronomer, said in a statement.
Blue Period
Luminous blue variable (LBV) stars are indeed incredibly rare; astronomers have only identified about 20 (maybe) and suspect there are only a few hundred in the Milky Way, tops.
Blue stars are stars that have at least 3 times the mass of the Sun and up. Whether a star has 10 times the mass of the Sun or 150 solar masses, it's going to appear blue to our eyes. An example of a blue star is the familiar Rigel, the brightest star in the constellation Orion and the 6th brightest star in the sky.
“There are dead stars that still shine because their light is trapped in time.
Some will exhaust their available hydrogen within a few million years. On the other hand, the least massive stars that we know are so parsimonious in their fuel consumption that they can live to ages older than that of the universe itself--about 15 billion years.
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