#stellar evolution

[fuckyeahfluiddynamics]

The Start of a Supernova

Stars about eight times more massive than our sun end their lives in supernovas, incredible explosions that rip the star apart. The earliest stages of this explosion are something we've never observed firsthand, until now.  (Image credit: ESO/L. Calçada; research credit: Y. Yang et al.; via Gizmodo)

[the-blaze-empress]

lifecycle of a star

There’s something on Corva-6p. Something perplexing. The signal was hazy, Ranboo said it was a scrambler, and a very advanced one at that. Even after Techno finally slept his highfire, the best Ranboo could tell them was that the scramble pattern looks Endran. It’s something of Ender’s, and Ranboo says that if he was given a few rotations he could probably crack it, but there’s an equal chance that they don’t have a few rotations. They don’t know what it is. --- Or, General Technoblade grows attached to an abandoned weapon of mass destruction

Chapters: 12/12

Words: 31,737

Fandom: Dream SMP

Rating: Teen And Up Audiences

Warnings: No Archive Warnings Apply

Relationships: Technoblade & Phil Watson | Philza, Technoblade/Phil Watson | Philza, Niki | Nihachu & Ranboo & Technoblade, Niki | Nihachu & Ranboo & Technoblade & Phil Watson | Philza

Characters: Technoblade, Phil Watson | Philza, Niki | Nihachu, Ranboo, Background & Cameo Characters

Additional Tags: Alternate Universe - Space, Space Opera, Philza Hardcore Lore References, Alternate Universe - Robots & Androids, Androids, Android Phil Watson | Philza, Hoglin Technoblade, Android Ranboo, He/Him Pronouns for Ranboo, The Syndicate, Military General Technoblade, BAMF Technoblade, BAMF Phil Watson | Philza, Implied/Referenced Abuse, Dehumanisation, Rehumanisation, Worldbuilding, Universe Building more like, Loyalty, Autistic Phil Watson | Philza, Post-War, Hurt/Comfort, Angst, Ambiguous Relationships, Ambiguous Technoblade and Phil Watson | Philza Relationship, emotions are hard

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Prologue: dark matter halo (1/1 chapters, 3k words)

Series: stellar evolution (2 works, 34k words)

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a little late BUT I WROTE A 31K SPACE AU!!! and a 3k prologue!! ive been meaning to write a space au for about 4 years so thank you to @antimony-medusa for giving me the opportunity to write one for her for fic in a box!! this is one of my favourite things ive written and im loving seeing other people enjoy it too

also i made a spotify playlist for the fic <3

[zespaceblog]

NGC 6752 - Globular Cluster

The third brightest globular cluster in our skies, and orbiting in the Milky Way's halo, this group of stars are over 10 billion years old (if not more), and yet, look closely and you'll spot a number of bright blue stars, how is this possible for a cluster of such age ? Most blue stars only last a few million years, so what is happening ?

Setting aside the one bright blue star in the image at 11o'clock which is a foreground star, you'll see countless red and blue stars in the cluster, yet there is no star formation going on here.

The vast majority of stars in the cluster are F,G,K,M type stars, stars a little larger than our sun down to red giants, as all the others have long since ended their stellar lives.

However, the blue stars are not new born stars as we often see in nebula, they are what is known as "blue stragglers".

The best theory for what is going on is that the dense cluster has meant some stars have actually merged, and the increase in mass has created a blue giant star, they won't last too long, but as globular clusters are some of the most dense areas of stars, there's a steady supply of mergers and blue stragglers.

[theexclusivestory]

Stellar Evolution: An In-Depth Journey into the Lifecycle of Stars

Stellar evolution tells the fascinating story of how stars are born, change, and eventually die. It's a process that takes billions of years and has a big impact on the universe and even life itself. In this article, we'll explore the journey stars take throughout their lives, looking at the different stages they go through and what causes them. Let's dive into the details of stellar evolution and understand how these celestial objects live and evolve.

Formation of Stars: Birth from Cosmic Clouds

Stars begin their journey in huge clouds of gas and dust called nebulae. These clouds are like giant factories that have all the ingredients needed to make a star. When something like a shockwave or a disturbance happens, parts of the nebula start to get denser. This denser area is where a new star begins to form. It starts as what we call a protostar. As more and more material gets pulled in by gravity, the protostar grows bigger and denser. Eventually, it becomes so dense and hot that nuclear fusion starts happening in its core. This is when the star "turns on" and starts shining.

The Main Sequence Phase: A Star's Brightest Period

When a star begins nuclear fusion, it enters its main phase, which is its brightest time. In this phase, hydrogen atoms in the star's center combine to form helium, releasing a lot of energy. This energy pushes outward, balancing the star's gravity and, keeping it stable. How long this phase lasts depends on how big the star is. Bigger stars go through this phase faster than smaller ones.

Stellar Metamorphosis: Beyond the Main Sequence

Once a star runs out of its hydrogen fuel in the center, it starts changing and moves away from its main form. What happens next depends on how big the star is to begin with. Different-sized stars go through different changes, each with its own special things happening.

Red Giant Phase: The Stellar Expansion

When stars like our Sun start running out of hydrogen, they enter a phase called the red giant phase. At this point, the star gets bigger and expands outward, but its core gets smaller and hotter. This makes the outer layers of the star glow red. Inside the star, helium starts fusing together, creating even more energy. This red giant phase shows that the star is getting closer to the end of its life.

Planetary Nebulae and White Dwarfs

When a star becomes a red giant, it swells up and eventually sheds its outer layers into space. This creates a beautiful cloud called a planetary nebula. What's left behind is the core of the star, which becomes a white dwarf. A white dwarf is a small, dense object about the size of Earth. It's made mostly of a special kind of matter called electron-degenerate matter. Over a very long time, white dwarfs cool down and become less and less bright. Eventually, they become invisible and mark the end of the star's life for smaller stars.

Supernovae and Neutron Stars: The Fate of Massive Stars

When big stars run out of fuel, they collapse suddenly, causing a massive explosion called a supernova. This explosion is so bright that it can outshine entire galaxies. During this explosion, heavy elements made inside the star's core are scattered into space, which later helps in forming new stars.

After a supernova, the core of the big star can shrink even more, forming a neutron star. Neutron stars are very small, like cities, and are made mostly of tightly packed neutrons. They have strong magnetic fields and spin very fast, leading to interesting things like pulsars and magnetars.

Black Holes: The Mysterious End

When really big stars run out of fuel, something incredible happens. They collapse under their own gravity, squeezing down into a tiny, super-dense point. This creates something called a black hole. Black holes are mighty, with gravity so strong that not even light can escape from them. They're like cosmic vacuum cleaners, sucking in everything around them. Black holes are mysterious and fascinating, and they impact how galaxies work, shaping the universe in a really big way.

Conclusion

Stellar evolution is like a never-ending story of how stars are born and eventually fade away. It starts with the peaceful formation of baby stars in cloudy areas of space called stellar nurseries. Then, stars grow and shine brightly during their main life phase. But as they run out of fuel, some stars become red giants, swelling in size. Eventually, smaller stars become white dwarfs, while bigger ones explode into supernovae, scattering elements into space. This process helps shape the universe, showing us how everything in space is connected. By studying stars, we learn more about where we come from and our role in the vast cosmos.

FAQs

Who came up with stellar evolution? In the early 1900s, two astronomers named Ejnar Hertzsprung and Henry Norris Russell found a helpful way to compare different stars. They called it the Hertzsprung-Russell (H-R) Diagram. It's like a big chart where scientists can see how stars compare to each other based on their brightness and temperature. This diagram has been super useful in understanding more about stars and how they work.

What are the elements of stellar evolution? These are some of the building blocks found in space i.e. hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, chlorine, sodium, magnesium, potassium, calcium, and iron.

What is the lifetime of a star? Very big stars burn through their fuel fast, so they don't live very long, maybe just a few hundred thousand years. But smaller stars use their fuel more slowly, so they can shine for billions of years. However, no matter how big or small a star is, eventually, it starts running out of hydrogen, which is what keeps it shining.

What is the stellar life cycle? Stars go through a cycle of being born, burning fuel, and spreading out material when they die. This cycle is ongoing and helps create elements that fill the universe. Depending on how much stuff a star has (its mass), it follows a different path in its life.

What are the 7 types of stars? Stars come in different types, and scientists classify them based on how hot they are. There are seven groups, starting with the hottest and ending with the coolest. They are named O, B, A, F, G, K, and M stars. O stars are the hottest and brightest, while M stars are the coolest and dimmest.

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TheExclusiveStory

Welcome to TheExclusiveStory! On this website we will share the content related to Real time facts and Astronomy.

[mindblowingscience]

Scientists catch real-life Death Star devouring a planet in 1st-of-its-kind discovery

The action 12,000 light-years away may presage what happens to Earth about 5 billion years from now.

Astronomers may have for the first time witnessed a sun-like star devouring a planet, shedding light on the fate that will befall Earth in about four billion years when our dying sun swells to engulf our world, a new study finds.

By analyzing countless stars during various stages of their evolution, astronomers have discovered that as our sun and stars like it near the ends of their lives, they begin to exhaust their primary source of fuel, the hydrogen near their cores. This leads their cores to contract and their outer shells to expand and cool. During this "red giant" phase, these stars may billow out anywhere from 100 to 1,000 times their original diameter, swallowing closely orbiting planets.

"We know that this must happen to all planets that are orbiting at distances smaller than that of the Earth, but it was considered extremely challenging to provide experimental evidence for this," study lead author Kishalay De, an astrophysicist at the Massachusetts Institute of Technology, told Space.com.

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[clwhowrites]

Prompt 27/2/25

The sun enters the next phase of it’s evolution early. Humanity has 100 years before the brightening sun makes the earth become uninhabitable.

[pigeontheoneandonly]

Astronomy 101: Stellar Life Cycles

This is the first in a series of posts I plan to make explaining basic astronomy concepts.  I am not a professional astronomer, but I have a B.S. in Astronomy and Astrophysics, experience performing professional astronomical research (primarily photometry), and a lifelong amateur interest in astronomy. I am committed to accuracy in these posts (though some simplification is necessary) and welcome questions/comments.

(Image source)

Nearly every aspect of a star’s evolution is governed by a single characteristic: the star’s mass.  Stellar masses are enormous, and so astronomers find it more convenient to measure them in solar masses (M☉, M being mass, and ☉ being the astronomical symbol for the sun, pronounced “M-sol”). 1 M☉ is equivalent to the sun’s mass; 2 M☉ is twice the sun’s mass; 0.5 M☉ is half the sun’s mass; and so on.  Our sun masses approximately two quintillion kilograms—that’s 30 zeroes!—so it’s easy to see why this convention makes comparisons between stars easier.  

Stars are composed primarily of hydrogen, with non-trivial amounts of helium (ex. our sun is about 74% hydrogen and 25% helium).  They fuse the elements within themselves to produce an outward pressure from radiation that balances the inward pressure imposed by their own gravity (gravity wants to collapse the star; radiation keeps this from happening).  The lowest stellar mass that can sustain a fusion reaction is theorized to be 0.08 M☉.  It’s not physically possible for a star to be smaller than this.  On the other end, the most massive stars range up to 250 M☉. (It should be noted that as the universe ages, stars are getting smaller; it is hypothesized that new stars cannot exceed 150 M☉.)

Stars are born from the gravitational collapse of giant molecular clouds (GMC), which are large, cold, and relatively dense pockets of interstellar gas.  It’s theorized that several mechanisms can trigger GMC collapse, including the shock wave from nearby supernovae, collisions with other clouds, or passing through the spiral arm of a galaxy (which is denser than other areas). These all disrupt the balance within the cloud.  As it collapses, it begins to fragment, forming individual stars.  One GMC will produce numerous protostars.  

The protostar phase lasts a relatively short time, about 500,000 years for stars the size of the sun. During this time, the protostar continues to accrete mass from the surrounding nebula (its own pocket of the GMC).  Gravitational collapse is countered by gas pressure and magnetic pressure rather than by nuclear fusion as the protostar grows.  Eventually, this is not sufficient and the protostar begins to collapse and enters a new phase: it reaches sufficient density to ignite nuclear fusion in its core, and becomes a proper star.

Initial fusion in the core fuses hydrogen into helium.  It may seem counter-intuitive, but the lower a star’s mass, the slower it burns through its fuel and the longer it remains in this phase of its life.  Massive stars are not only much hotter than small stars, but they need to produce more energy to stave off gravitational collapse. This causes them to burn through their supply of hydrogen very quickly.  Very low mass stars born early in our universe have not existed long enough to burn through their hydrogen supplies.  Models predict stars of 0.1 M☉ will take 6-12 TRILLION years to exhaust their hydrogen, and our universe is only 13.8 billion years old.  These stars are barely getting started.  These stars, known as red dwarfs, will never become red giants.  Instead, they will continuously mix their original hydrogen stores with their newly produced helium until the entire star is composed of helium, at which point fusion will shut down.  As they reach the end, they are predicted to become blue dwarfs, and then eventually white dwarfs.  No blue dwarfs presently exist because the universe is still young.

Stars more like our sun, ranging from 0.6 to 8 M☉, have lives more consistent with what many people are taught in high school science classes.  When these stars exhaust the hydrogen in their core, they still contain a large volume of hydrogen in their outer layers.  They enter the subgiant phase, where they fuse hydrogen in a shell surrounding the helium core, and the star begins to expand and cool.  This new helium adds to the volume of the core, the hydrogen-fusing shell moves outwards.  This phase lasts several million to two billion years, again with lower-mass stars spending longer in this phase.  

(You may have read that the sun will get hotter as it ages.  This is true, and it’s due to the fact that as the fraction of hydrogen in the core decreases, the core temperature and rate of fusion increase.  The sun will contract and become hotter as it approaches the subgiant phase.  It’s theorized that this will make the Earth uninhabitable in about one billion years.  However, the effects of plate tectonics and specifically the subduction of water from the oceans and the gradual slowing of tectonic activity is likely to play as large a role if not larger.)

This hydrogen-burning shell supports the star against gravitational collapse until the helium core grows too large.  The core will contract, and the outer layers will further expand and cool as the star becomes a red giant.  In the case of our sun, its radius will expand beyond the orbit of the Earth, in about six billion years.  Shell burning continues at an increasing rate, but the star is no longer in equilibrium, and the core continues to contract even as it increases in mass, until eventually the star begins fusing helium into carbon.  This can happen very suddenly for stars at the lower end of this mass range, or more gradually for more massive stars.  The growth of the star can also temporarily create new habitable zones, primarily for the moons of gas giants, lasting several hundred million years.

Stars in this mass range do not have sufficient mass to fuse carbon, and so when the helium is largely consumed in the core, the core begins to collapse, and this time, only a strange state of matter called electron degeneracy will stop it.  The Pauli Exclusion principle states that no two electrons can occupy identical states, and electron degeneracy occurs when a star has collapsed to the point that all the electrons of the star have been forced to occupy all the lowest-available energy states within the atomic structure of the star. The energy of the gravitational collapse is insufficient to overcome this electron pressure.  White dwarfs are very small and incomprehensibly dense; similar to the mass of the sun, they are similar in size to the Earth.  A teaspoon of white dwarf would weigh about 15 tons. Fusion has ceased, and the star is an inert ball of slowly cooling degenerate matter.

This is the end of the road for stars in this mass range, which is most of the stars that presently exist in the universe.  Very, very slowly, solo white dwarfs will continue to cool.  White dwarfs are predicted to outlast the lifespan of galaxies as structures in our universe.   They may still be extant when enough time has passed for proton decay to become a significant force and ultimately devour the white dwarf.  If proton decay takes significantly longer than predicted or turns out to not exist, the ultimate fate of a white dwarf is to be devoured by a black hole in the very, very, very far future of our universe when other forms of stars have all ceased to exist.  (The black hole era is predicted to begin 10^43 years after the Big Bang, but it’s dependent on a lot of poorly-understood factors.  Safe to say, this is not anything anyone needs to worry about.)

More massive stars have a more interesting if shorter life.  They blow through their hydrogen quickly, ranging from 1 billion years to as few as 10,000 years. (You can calculate here.)  As these stars enter their supergiant phase, they lose mass rapidly due to strong stellar winds.  These stars do possess enough mass for more complex fusion reactions, and will gradually develop shells fusing various elements, and finally in the core, ultimately producing iron via fusion.  All elements aside from hydrogen, some helium, and small amounts of lithium and beryllium are created by stellar nuclear fusion.  Iron, however, is special, because it is the lightest element on the periodic table that requires more energy to fuse than it produces through fusion. A star attempting to fuse iron is going into an energy deficit, rather than producing energy through radiation that can stave off gravitational collapse.  A star cannot fuse iron.  

The final days of such stars come on quickly.  The core turns to iron within a few hundred years, so rapidly that there is little change in the outward appearance of the star, which continues shell burning right up to the end.  Eventually, this iron core reaches the effective Chandrasekhar mass, a little larger than the mass of our sun, and the core can no longer support itself.  The core collapses.

It’s easy to say the star then explodes in a supernova, but the truth is more complicated.  A supernova is triggered by the release of gravitational potential energy from the core collapse.  If this is insufficient, instead the core becomes a neutron star or a black hole with very little fanfare.  Some supernovae (pair-instability supernova) do not leave behind any stellar remnant despite originating from supermassive stars.  Other supernovae do not involve supermassive stars, but white dwarfs in binary pairs accreting matter from their stellar companion.

The core collapse takes less than a quarter of a second.  Within a few hours, the shockwave reaches the surface of the star, which will brighten tremendously over the next few months.  At peak, supernovae can outshine their host galaxies.  Perhaps the most famous supernova, SN 1987A, was visible to the naked eye and wasn’t even located in our own galaxy, but in a satellite galaxy.  This shockwave is incredibly high-energy, to the point that it not only ejects outer material from the star, but ignites fusion reactions in that material. Here, we have an excess of energy, and nuclear fusion reactions that require more energy than they create are possible.  This is how all elements heavier than iron are created. 

The core becomes a neutron star or a black hole.  Which depends on a large number of variables, perhaps strangely only two of which are core mass and stellar mass.  A neutron star is similar to a white dwarf, in that it is composed of degenerate matter, but in this case electron degeneracy was not strong enough and it is held up by neutron degeneracy.   In this state, electrons have combined with protons to produce neutrons, leaving behind a highly dense star composed of nuclear matter. While a neutron star is again slightly more massive than our sun, it has a diameter of only about 20 kilometers. A teaspoon of neutron star weights approximately 4 billion tons.  Many neutron stars rotate rapidly, giving off jets of radiation from their poles. These stars are known as pulsars. The fate of neutron stars is similar to that of white dwarfs; they will eventually merge into black holes in the far distant future.  

Other stars become black holes. In this case, even neutron degeneracy cannot stave off gravitational collapse, and the core collapses into a singularity.  A singularity is a poorly-understood object where spacetime curvature becomes infinite. We can study singularities mathematically, but we can’t observe one, because it is hidden behind an event horizon—a boundary surrounding the black hole where gravity is too strong for even light to escape.  And if light can’t escape, we can’t observe anything inside the event horizon.  Our current understand of physics also breaks down here; our theories of gravity aren’t sufficient to fully understand singularities.  We can, however, study event horizons, accretion disks (matter falling into the black hole), and jets of particles and radiation some black holes exhibit.  This has given us a good understanding of the external properties and behavior of black holes, and we detect them based on these characteristics and the effects they have on other objects (ex. an orbiting companion star).  

So if everything eventually becomes part of a black hole, what happens to a black hole?  The answer is they evaporate through a process called Hawking radiation.  Essentially, according to quantum mechanics, space has a quality called vacuum energy that causes virtual particle pairs to continuously pop in and out of existence. The pair consists of one particle and one anti-particle, which annihilate each other and return the energy of their creation to the vacuum.  Therefore, no energy is created or destroyed.  However, every so often, one of these pairs pops into existence with one particle on the outer side of the event horizon, able to escape, and the other trapped inside the event horizon.  The virtual particle that escapes becomes a real particle, and that energy has to come from somewhere.  It takes it from the black hole.  Because mass and energy are functionally equivalent, this drains a tiny amount of mass from the black hole.  (Please note: this is a dramatic oversimplification, but gets the basic idea across.)  On long enough timelines, this will cause even the largest of black holes to evaporate. Unlike just about everything else involving stars, smaller black holes evaporate more quickly than large ones.  

[ravewing]

hello astronomy tumblr!!😁

so erm. im participating in science olympiad and i have to study stellar evolution (i think star formation specifically but i assume ill have to know the other stuff as well) and exoplanets but uhh i have NOT studied SHIT all year and regionals are in a month so. if anyone is knowledgeable in this area. please i need help i am begging anything helps if you dont know anything then tag like a friend who might idfk please i am desperate🙏🙏🙏