Stellar structure models are used to describe the internal structure of a star, making predictions about its luminosity, color, and future evolution. Different classes and ages of stars have different internal structures, reflecting their elemental makeup and energy transport mechanisms. The objective is to describe the entire internal structure of a star in terms of its fundamental physical properties and to model how this structure will change over time.
The core of a star is the hottest and most dense region, and as one moves away from the star’s center, the core becomes more dense. Any theory of stellar structure must explain the observed properties of stars and seek clues in correlations among the observed properties. This book is divided into two parts: stellar interiors and stellar atmospheres.
The internal structure of a star contains a mixture of ions, electrons, and radiation (photons). For most stars, the ions and electrons can be treated as an ideal gas, and quantum effects can be neglected. The internal structure of a main sequence star depends upon the mass of the star. In stars with masses of 0.3-1.5 solar masses (M), including the Sun, the average particle mass, μ, is strongly magnetized.
Nuclear fusion is what makes a star what it is: the creation of new atomic nuclei within the star’s core. Many of stars’ properties, such as how long they live, what they contain, and their life cycle, are held together by gravity. Astronomers have probed the magnetic fields in the mysterious inner regions of stars, finding they are strongly magnetized.
In conclusion, stellar structure models help explain the observed properties of stars and provide insights into their internal structure, temperature, density, pressure gradients, and life cycles.
📹 The Sun: Crash Course Astronomy #10
Phil takes us for a closer (eye safe!) look at the two-octillion ton star that rules our solar system. We look at the sun’s core, plasma, …
What is the interior of a star’s core made up of?
A stellar core is the hot, dense region at the center of a star, where the temperature and pressure conditions allow for energy production through thermonuclear fusion of hydrogen into helium. This energy counterbalances the star’s mass, maintaining thermal and hydrostatic equilibrium. The core is surrounded by the stellar envelope, which transports energy from the core to the stellar atmosphere.
Main sequence stars are distinguished by their primary energy-generating mechanism in their central region, which joins four hydrogen nuclei to form a single helium atom through thermonuclear fusion. The Sun is an example of this class of stars. Once the core region reaches thermal equilibrium after about 100 million years, it becomes radiative, allowing generated energy to be transported out via radiation and conduction.
At lower stellar mass, the outer convection shell takes up an increasing proportion of the envelope, and for stars with a mass of around 0. 35 M ☉ or less, the entire star is convective, including the core region. Very low-mass stars (VLMS) occupy the late range of the M-type main-sequence stars, or red dwarf, and form the primary stellar component of the Milky Way at over 70 of the total population.
The temperature of the core region for a VLMS decreases with decreasing mass, while the density increases. Even at the low end of the temperature range, the hydrogen and helium in the core region are fully ionized.
What element is inside stars?
Stars are composed of extremely hot gases, containing only 98 hydrogen and helium, the two lightest elements in the universe. Despite being light gases, they have enormous mass, making them dense in the center. The gas at the Sun’s core is ten times denser than gold, making it ten times heavier than gold. Stars are formed from massive clouds of hot gas, similar to those on the Sun’s surface.
What are the interior layer of a star?
The inner layers of a star consist of the core, radiation zone, and convection zone, followed by the outer layers. The photosphere is where energy from the inner layers becomes visible, as photons created in the core take thousands of years to travel to the surface due to constant bouncing off atoms. The photosphere is the region where the density becomes low enough that most outward photons are irradiated into space.
There are two additional layers in the star’s atmosphere, the Chromosphere and the Corona, visible during a solar eclipse. If a star is habitable, it provides a reliable and constant supply of heat through radiation, which warms the atmosphere molecules. If a star is too far away, the photosphere can still be seen in the form of a bright white light.
What are the structures of a star?
The core-envelope structure of a star is formed by the application of significant pressure, resulting in the formation of a hot, dense central core surrounded by a cooler, lower-density, extended envelope. The primary feature of the Hertzsprung-Russell (H-R) diagram is the main sequence (MS), which exhibits a strong correlation between luminosity and temperature. This implies that hotter stars are brighter than cooler ones.
What is the inside of a star like?
Stars are composed of hydrogen and helium gas, with the high temperatures and pressure found within their cores allowing four protons to fuse to form helium. This process releases a considerable amount of energy, which enables the stars to emit a brilliant light.
What is the interior layer of a star?
The core constitutes the central layer of a star, whereas the radiative zone represents a dense shell of cooler hydrogen situated above it. This region is characterised by the transfer of light energy from atom to atom as it ascends.
What is the composition of the star?
Cecilia Payne, a renowned astronomer, conducted a groundbreaking study on the absorption lines in stellar spectra. Her doctoral thesis, the first awarded for work at Harvard College Observatory, demonstrated that the wide variation in stellar spectra is primarily due to the different ionization states of atoms and surface temperatures of stars, not to different amounts of elements. Payne calculated the relative amounts of eighteen elements and found that the compositions of stars were nearly the same among different types.
She discovered that the Sun and other stars are composed almost entirely of hydrogen and helium, the two lightest elements. The heavier elements, like those making up the bulk of Earth, account for less than two percent of the mass of the stars. This groundbreaking discovery led to the publication of her book Stellar Atmospheres, which was well-received by astronomers. Payne’s work demonstrated the ability to “read” the surface temperature of any star from its spectrum and the Hertzsprung-Russell diagram, a plot of luminosity versus spectral class of stars, which became the most powerful analytical tool in stellar astrophysics.
What is the interior structure of a star?
The interior of a star is composed of ions, electrons, and radiation (photons). In the majority of cases, ions and electrons are treated as ideal gases, which allows for the neglect of quantum effects.
What makes up the atmosphere of a star?
Stars have a low-density outer region called the photosphere, which is mostly transparent to light. Most stellar atmospheres consist of a photosphere, chromosphere, transition region, and corona, similar to the solar atmosphere. However, some evolved stars and B and A main-sequence stars lack transition regions or coronas. The photosphere and chromosphere absorb radiation at specific wavelengths, resulting in dark absorption lines called Fraunhofer lines. These lines provide information about the star’s chemical composition, pressure, temperature, rotation, and magnetic field strength.
What is there inside the star?
Stars are hot gas balls, primarily hydrogen, with some helium and other elements. They have a life cycle ranging from a few million to trillions of years, and their properties change as they age. Stars form in molecular clouds, which are cold and create high-density pockets. Gravitational force strengthens these clumps, leading to their collapse. Gravity causes some of these clumps to collapse, causing friction and the development of a protostar, or baby star. These protostars are called stellar clusters, and molecular clouds full of stellar nurseries.
The protostar’s energy initially comes from heat released from its initial collapse. After millions of years, immense pressures and temperatures in the star’s core cause the nuclei of hydrogen atoms to form helium, a process called nuclear fusion. This energy heats the star and prevents further collapse under gravity.
What is a star mainly made up of?
Stars are composed of hot gas, primarily hydrogen and helium, which are the lightest elements. They shine by burning hydrogen into helium in their cores and later create heavier elements like carbon, nitrogen, oxygen, and iron. These elements were created by previous stars. When a star runs out of fuel, it ejects much of its material back into space, forming new stars and recycling the material in stars.
📹 ASTR 503 – Class 19 – Video 1 – Intro to Stellar Structure
Let’s look at the internal structure of stars you see here is a drawing of the internal structure of the sun you have the region here …
You know I just take the heat of the Sun for granted, especially growing up in Arizona. Of course the Sun is hot, I know that, you know that, we all know that. But it didn’t hit me until I watched this how amazing it is that I can feel that heat from so far away. I love that little feeling of realization.
I remember the day I realized the Sun was just another star when I was a child. It was a mind blowing realization and allowed me to step into a bigger world where I understood not all things I see or experienced were correct. That there are hidden meanings, connections and explanations that everywhere in the world.
CrashCourse, it’s partly because of you that I started making articles (in fact, I uploaded my first articles only a couple weeks ago!) in the hopes that I can help people aspire to look at the world through a scientific perspective. And if anyone here is interested in perusal more science-based articles, please give my website a try! I strive to make my articles as visually appealing as possible, and as a grad student who is trying to put himself through school while also supporting his parents, your support and viewership would be greatly appreciated! Thank you guys 😀
CME is not really a direct event to compire it to flares, its a result of different sun events which cause various ejections. 2 common causes is: -Flare which blasts surrounding material -Filament Release where that released filament is… ejected and practically becomes CME by it self. In other words flare is a explosion, CME is a shockwave (of charged particules) which travels thru solar system
I LOVE the Crash Course series, but in this case some of the statements are misleading. Suggesting that scientists have a firm grip on solar mechanics is misleading and may bias young curious minds. It is OK discussing what the interior of the Sun MIGHT consist of, but it must be presented with the caveat that we can only speculate, and that these are suppositions. Our understanding of plasma behavior is at best rudimentary; we know that the Solar plasma state has a magnetic potential many magnitudes more powerful than its gravitational consideration. As proof of this, one can plainly see that the plasma loops on the Sun, consisting of millions of tons of looping matter, utterly ignore the Sun’s crushing gravity while in a plasma state. Is it not sometimes more important presenting what we don’t know than what we think we know? …Otherwise, love these documentaries. Think of this comment as tough love 🙂
How things where be so different for me when I was a kid, all I got when ask what the sun was? is that it is a giant gas ball burning in the space, and this was not from my mom, this was from all the information available to me at the time, in any case, thank you guys for let me know a more detailed answer to a question long time made.
The power density in Sun’s core (from the hydrogen fusion) is the same as an active compost heap. It’s 30 Watts / m**3 which is a dim 30-Watt light bulb inside a large tea chest, with many of those tea chests stacked up, many of them, many many many of them. Sun’s core is very very big. That’s why it’s a sonofabitch to get that hydrogen fusion working on Earth. A dim 30-Watt light bulb inside a large tea chest like in Sun’s core just don’t cut it on Earth.
Chemical element #120 (8s2), with all 120 electron spots filled, is probably inside stars. When it’s neutron splits, it gives off one proton, one electron and energy. 1P and 1e are basic hydrogen of what the Sun is primarily made up of and the Sun certainly gives off energy. With it’s position on the Periodic Table of Elements, it probably only exists inside the Sun in a Plasmic state of existence.
While this is a very detailed explanation of the workings of the Sun, the explanation about auroras could be misunderstood. The energetic particles do not have enough energy to cause auroras directly. What happens is that the magnetic field from the Sun and the earth get entangled and earth’s field lines stretches out on the far side of the Sun. At some point these field lines collapse again and the released energy is transferred to the charged particles in the solarwind, and they then generate auroras…..as far as I understand it.
The way my Astronomy professor explained the population of stars was to compare it to birds. Sure the birders search for all of the fancy birds, but the vast majority of birds are “Little Brown Birds” or LBBs, which nobody pays much attention to. Sure, everybody wants to see a Bird-of-paradise, but our sun is more like a mallard.
Hey, great work explaining such a topic! It was, to me, a perfect manner. At the start, it seemed like this article was going cool, but it just went nuts when focusing on the Sun’s magnetic field. It’s great to learn about the relations between its magnetic field and the dynamics of those Solar events. Thanks a lot!
This was a great article, you guys have such great production for an educational website! Also you’re not annoying to listen to that helps lol. It’s fascinating how much damage could be done by a large enough solar storm. Knocking out satellites could cause a mass outage in GPS, which is also how all of our computers synchronize their clocks. When a computers clock is out of sync it effectively can’t do anything at all without errors as the processor is very reliant on accurate time keeping. Imagine if every computer in the world was incapable of doing anything?? There goes our internet, our banks, logistics, entertainment, transportation, resource management, government, hospitals, the list goes on! It would be complete and utter chaos and would likely lead to an unprecedented level of suffering and death. It’s honestly completely terrifying to think about. So on a brighter note (pun intended), please keep making these articles and educating people! More inquisitive minds in the world will likely lead to the next generation of technological and scientific advancement, which could very well save lives.
A toy is an item that is used in play, especially one designed for such use. Playing with toys can be an enjoyable means of training young children for life in society. Different materials like wood, clay, paper, and plastic are used to make toys. Many items are designed to serve as toys, but goods produced for other purposes can also be used. For instance, a small child may fold an ordinary piece of paper into an airplane shape and “fly it”. Newer forms of toys include interactive digital entertainment. Some toys are produced primarily as collectors’ items and are intended for display only. The origin of toys is prehistoric; dolls representing infants, animals, and soldiers, as well as representations of tools used by adults are readily found at archaeological sites. The origin of the word “toy” is unknown, but it is believed that it was first used in the 14th century. Toys are mainly made for children. The oldest known doll toy is thought to be 4,000 years old. Playing with toys is considered to be important when it comes to growing up and learning about the world around us. Younger children use toys to discover their identity, help their bodies grow strong, learn cause and effect, explore relationships, and practice skills they will need as adults. Adults on occasion use toys to form and strengthen social bonds, teach, help in therapy, and to remember and reinforce lessons from their youth.
Hey guys! I just saw a article about the Sun’s nuclear fusion, and it says that the Sun’s core isn’t that hot, and because of that, the atoms woudn’t fuse, but they do due quantum tunneling! A way to understand quantum tunneling in this case is to think about that the fusion reaction will happen, even with low temperature and pressure, in a given probability. Due to the very big number of atoms “trying” to fuse, some of them finaly get it. Is this true? Thanks, Bruno Adipietro
@1:35 to help you grasp the enormity of the pressure at the core of the Sun, consider that it is equivalent to the pressure at the depth of 2,594,706,798 km. That considering the deepest depth the men could ascend to is currently standing at 10898 meters, or mere 10.9 km!!! That’s at least 259,470,579 times less than the pressure we’d experience at the core of the Sun! Think about that!
I dont think the loss of our entire sat network would be THAT devastating. Not even close tot he 2008 crisis, for instance. Planes could still navigate just as they did until the mid 80’s when the GPS network wasnt available, and could still talk to everyone over VHF, which is still mandatory, even if rarely used over the atlantic. The same with sea traffic. Some isolated areas would loso comms. The internet wouldnt notice much, everything is ground-based (or sea-based, in sub-aquatic cable’s cases) so it would still work just fine. Weather sats would be out and that would be inconvenient, but hardly disastrous on a global scale. Early warning systems would also be out, but without GPS, GLONASS and such it’s difficult to pint ICBM’s so i dont think anybody would fire any. Besides, there is no reason to do so. As for the power network, core systems are a lot hardier than people give them credit for. Blackouts would be bad, but probably taken care of in weeks, if not days. I cant think of anything that would be so disastrous that we wouldnt be able to watch this vid 3 years after the event in question. Which doesnt mean i think we shouldnt study it carefully to have some preventive measures in place, of course.
The reasoning, behind the corona’s heat: Is probably similar, to the one, which made finding, the remaining mass, from the “missing baryon mystery,” so hard; besides, considering the location of the corona, it also makes sense, the answer should probably be: (I suggest, if you haven’t already; that you check out, PBS Space Time’s article: The missing mass mystery.) Due to it’s location, and it’s density; it absorbs more heat, that it can radiate away. Since the density, is so low, the mass in the corona, cannot effectively rely, on vibrations, to lose energy, neither is it hot/dense enough, to release that heat, through fusion; hence, the only reliable way, is through photon emission, while it’s being bombarded, with high energy particle/photons. There’s probably, also some sort of convection, that goes on, in the corona, as well; which would aid in this progress, though I suspect, that the convections, would mostly be moving, towards the sun. (I.e. Aiding in keeping the corona, so hot.)
I super enjoy your teaching methods and it’s easy to catch on for me with said methods but holy scheiße the way you say kilometers bugs me SO much for some stupid reason lol! It’s dumb but I just can’t help it it’s like nails on a chalkboard or silverware scraping on a dish!BUT other than that, I really super enjoy the astronomy crash courses! 🤓 thanks for dumbing it down for my brain!
There’s sometihng I never understood about solar flairs bringing our society to our knees. As far as I know, shielding electronics against electromagnetic radiation is a thing. In fact, as far as I know, a proper shield lets NOTHING electromagnetic pass through it, on matter the intensity. So…. Can’t the powergrid and especially satelites protect themselves? I mean really are satelitles sent into space unshielded? Also, if green energy had developed proerply we might be desiring a solar flair right into our face. If the tech to turn excess electricity into gas or graphene were developed enough, we could cheed when a solar falir hit earth because it would mean free energy for the next 10-20 years or more. Seems to me, solar flairs are a problem because we allowed them to be a problem.
the sun is a ball of plasma…. not gas, two completely different forms of matter. for those who don’t know what plasma is, it is gas heated to the point where its electrons get stripped from the nucleus. just think about it this way. Heat up a solid, it melts and becomes a liquid, heat up a liquid it boils and becomes a gas. Heat up a gas enough and it IONIZES into plasma (ie. the electrons being stripped from the atom core).
1.4KWatt for each square meter at the earths equator, on a good day of course. That’s the amount of EM from the sun we get, that’s what enable’s us to have solar panels that can produce clean energy. The UV from the sun is what generates photosynthesis for plants and is the source of ALL your food. Thankyou Sol for all those free things. ☼
One thing I don’t understand is how much the loss of mass from the Sun affects the orbits of planets. By the solar wind and coronal mass ejections, plus the small amount it “looses” as it transforms matter into energy, I would guess the Sun gets a bit lighter every year. But how lighter? And does such loss of mass extends the planet’s orbits?
Phil, a small pet peeve: “a 100 times the diameter AND 1 million times the size”. It would be a great opportunity in an educational article to take some time to explain how this is the same piece of information because volume scales with the cube of the diameter, but I find that nobody does explain it.
Theoretically, if I could position myself in space with both the Sun and Earth in my vision … and if I held a big, opaque board that blocked the sunlight from the Earth … then, if I lifted the board to let the light through, could I actually see the light travel from the Sun to the Earth over the next 8 minutes (assuming that there’s some space dust to reflect the light)?
What is really surprising is that the amount of heat produced in the core is actually very small in terms of volume. The amount of continuous energy produced in a cubic meter of the Sun’s core is only about 280 watts, roughly the same as 3 regular tapered candles. It’s the huge size of the core, and the resultant sum of all this energy that makes the Sun so hot.
Wow! This article has provided me so much insights into what the sun’s effects on our civilisation are / can be! Even if a solar storm hits the Earth in the future without us knowing and all telecommunications become shut off due to the failure of the global electric grid, I would know how to respond since I know the cause! Perhaps this is useful knowledge, no one can tell!
I got an old safe off Craigslist for a few hundred dollars. I’ve converted it into a faraday cage on the cheap. Inside I’ve got CD player. When the grid goes down I may not have TV or the Internet but I will have my tunes even if I have to use a hand crank generator for electricity. Of course I keep all my computer backups in there with an old laptop just in case all my other stuff gets fried. If you are really worried about this then maybe my solution is something to consider.
Really you are a good lecturer . In your view, your lecture is true . If you know about formation of Stars, Planets etc, really you can give an unforgettable lecture . The World must know about formation of the Universe, as soon as possible . Now the World is not in a position to understand the real facts . Though I am telling the truth, the World is not in a condition to pay attention with my words . I am the only man on Earth who know the total knowledge about formation of the Universe .
Hmm…does anyone else think that this host is a little patronizing in comparison to the others? I don’t know, it just feels like his tone of voice and the way he directs his words are more suitable for an audience of children. Trying to look past it since I do find the content interesting but it’s really distracting.
I think that you shouldn’t mention eye protection for “seeing sunspots”. That implies that you look directly at the sun, and that you would need goggles to dim the light of the sun, when in fact observations of the sun can be done without any eye protection as shown here. skyandtelescope.com/observing/sketching-sunspots/
Is the corona so hot because the molecules have escaped the suns mass and there4 theyve stopped bumping in2each other exchanging energy and once they reach space there is a lack of particles to release thier energy quickly, with this im thinking that yh space is cold but lacks particles to share energy with to efectively cool down the corona or isit the opposite un 1nce particles reach space they can radiate energy away making the corona hotter than the surface. rAyZoR.
The fact that the sun could so massively effect us that it could take out the power in 2012 and it still be down now rattled me. So much of our lives are based around tech now even beyond social ways. It would be chaos. I hope that there are some sort of plans in government vaults for how to pick up the pieces if that were to happen.
Why can we not have mass solar powered fields in the Sahara desert, and all other unhabitable hot and dry places for fuel, there could be millions of them all over the world, and makes things much more friendly, cost effective, and possibly used to pump sea water filtered to the people who need it to irrigate whole countries at a time so they can prosper, and end misery for millions of people. The answer is on Earth not in space.
some idea popped on my mind that if the cores element pressure to the atmosphere is the same as object its heavy cuase there similar elements (for example) the earth’s core is iron and flourine and so the highest or possible object that has the heavy pressure is most likely Iron and other mineral ore.
The sun is powerful enough to power a star right, so when our star runs out it will expload and when that happens can’t we harness its energy to power another star to run our solar system.I mean if its able to create even a little of energy to power a star that all we need.But once that happens we need a star thats not that far away but is close enough to power our solar system.