Astronomy

Why is our Sun hotter than UY Scuti?

Why is our Sun hotter than UY Scuti?


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As Wikipedia says the surface temperature of UY Scuti is 3,365 K and the sun is 5,778 K

Why is the Sun hotter than a supergiant star like UY Scuti?


UY Scuti is a red supergiant star.

When stars start to run out of hydrogen fuel, their cores start to collapse, causing the core of the star to heat up, and heavier elements start to be used as fuel. This means that the core of the star is hotter and producing more energy.

The effect on the outer layers of the star is to cause them to expand, and as things expand, they cool. The outer visible layer of the star cools (to about 3500K)

So the energy output of the star increases, but the temperature of the outer layer decreases. As you might expect this leaves the star unstable, and UY Scuti undergoes semi-regular variations in brightness.


Our Sun is an average sized star: there are smaller stars and larger stars, even up to 100 times larger. Many other solar systems have multiple suns, while ours just has one. Our Sun is 864,000 miles in diameter and 10,000 degrees Fahrenheit on the surface.

In 2017, an international team of astronomers announced the discovery of a so-called red dwarf star that’s so small it barely functions as a star. Code-named EBLM J0555-57Ab and lying some 600 light-years away, it’s similar in size to the planet Saturn.


What Is the Biggest Star in the Universe?

Some people may think that our Sun, which the Earth revolves around, is the brightest star in the universe. This, however, is not true. Therefore, you may wonder, what is the biggest star in our universe?

The problem with this questions is that the universe is HUGE, and we haven’t touched, photographed, or seen all of it quite yet. Instead of pinpointing the biggest star in the universe, we can clearly point to the biggest star that we humans have identified and seen.

We then have to consider how we are measuring these celestial bodies. Are we weighing them? Are we taking a tape measure around their waist to measure their circumference? Scientists like to use the measurement called the “solar radius” and “solar mass.” They like to use our Sun to measure size. This means scientists like to place stars and suns next to our own Sun to see how these objects compare. The solar radius is 690,000 km and the mass is 4.3 x 10^30 pounds.

Supergiant stars are the largest stars, and they are much larger than our own Sun. Some of them are thousands of times bigger than the Sun. Betelgeuse, which happens to be the 9th brightest star in the sky, is much larger than our Sun. The radius of this star is up to 1200 times than of our sun. That means if Betelgeuse was placed where our sun is now, it would eat Jupiter.

If you think Betelgeuse is large, it does not even compare to the largest star we have located. The largest star we have identified is UY Scuti, which was found in 2012. Its radius is in between 1,054,378,000 and 1,321,450,000 miles, which is about 1700 times larger than the radius of Sun. If you replaced our Sun with UY Scuti, the star would go beyond the orbit of Juptier, consuming all the first five planets, and drawing all the celestial bodies around it towards it.

Scientists have begun to classify UY Scuti as a hypergiant star, which means it is more massive than a supergiant. While UY Scuit may be the brightest, it actually is not the most massive. UY Scuti is around 30 times the mass of the Sun, but there are other stars that measure in around 265 times larger than the mass of our Sun.

UY Scuti is the biggest star we have identified to date, but this could change as scientists continue to research the stars. Our Sun is by no means a large star, but scientists like to use our Sun to measure the size and scope of other stars we find.


I rendered a quick picture showing the comparison of our sun to UY Scuti, the currently largest known star at an astonishing 7.94 AU.

Not sure exactly what you're picturing when you say "orbiting it just like a planet" but what I imagine you're suggesting is a binary system where the more massive star doesn't move, only the smaller star is moving around it.

However, the reality is that gravity is reciprocal, with both bodies pulling on each other. Any orbiting body will cause the other body to experience a force, and thus, a movement. Even the Earth's orbit alone causes our sun to wobble slightly. Only a very small amount, but it does cause a pull.

So a better definition would be to say that a star in a "planet like" orbit is one where the barycenter of the two-body system is within the more massive of the two bodies. If the barycenter was outside the more massive star, then it would be two stars orbiting a common point. Unfortunately, this definition has problems too -- Jupiter and the Sun, in fact orbit a common point just slightly above the surface of the sun, so it's not exactly a definitive or exhaustive test of what might constitute a "planet like" orbit. The good news is, both scenarios do happen in binary star systems, so there are plenty of candidates for the planet-like orbit you're probably picturing.


Size comparison between our Sun and the largest star ever observed: UY Scuti

I'll say the same thing I've said before: take this with a grain of salt.

When we get the radius of a star we do so mathematically,

where everything is in solar units. L and T are both easily measureable. But this doesn't really tell the whole story.

The outer atmospheres of hypergiant stars are incredibly diffuse, often less dense than air. So you see this nice defined boundary in the above image, but it's not like that at all. To compare, the surface of the Sun is about as dense as water,

1 g/cm 3 . The "surface" of UV Scuti might be

0.0001 g/cm 3 . Are we really comparing apples to apples?

I know I'm nitpicking, but imagine it like this: do you consider the Earth's radius to stretch to the exosphere? That is what we're doing here. Hypergiants like this have flipped internals (compared to the Sun): they have convective cores with a radiative envelope. with some shell burning and mixing added in. The reaction rate for triple-alpha scales as T_6 (the temperature in millions of Kelvin) to the 40th power. Temperature scales as inverse density. That's how these stars have such huge envelopes.

Like I said, I know it's nitpicky. And I'm sorry. I think large stars are awesome too, they're my favorite part of astrophysics. I don't mean to take anything away from the awe of it. But they're not as cut and dry as they're depicted.

EDIT: Wanted to highlight a point /u/uforeader brought up: I had not considered optical depth. If we consider the photosphere to be the surface, and use a tau

2/3 to define the photosphere, it's entirely possible that the surface of such a star could be as diffuse as I have pointed out. Touche, /u/uforeader. /u/DrunkHacker also brought up the same point and I missed it.

I still stand by my point that these aren't nearly as clean as they're always depicted, but I also stand corrected.


Apparent (Brightness) and Absolute Magnitudes

UY Scuti has an apparent magnitude of 11.20, this is a measure of the brightness of the star as seen from Earth. Apparent Magnitude is also known as Visual Magnitude. Using the supplied Parallax value, you would get an absolute magnitude of 0.24

Absolute Magnitude is the apparent magnitude of the star from a distance of 10 parsecs or 32.6 light years. This assumes that there is nothing in between the object and the viewer such as dust clouds. To really compare the brightness of the star, it is best to use Absolute rather than Apparent Magnitude.

Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.


What UY Scuti Looks Like In Real Life

Tags: anton petrov, education, #education, space, astronomy, universe, whatdamath, what da math, science, game based learning, UY Sct, BD-12 5055, IRC -10422, RAFGL 2162, HV 3805, uy scuti, uy scuti planets, uy scuti vs sun, what uy scuti looks like, giant stars, red giants, orange giants, red giant, orange giant, yellow giant, supergiant, megagiant, ultragiant, giant star, what giant stars look like, What UY Scuti Looks Like In Real Life

These girls thick and juicy and squirting that plasma shit

You can achieve kind of effect in space engine, by messing around with the star corona settings, exposure, and high bloom, I did so here, and it turned out really good : https://imgur.com/a/SsRUq3t

Black hole-oh so you say you aint die- UY scuti-ye-black hole-bye uy scuti

And how would you know that? Because some program tells you that? Programmed by guy who never saw a hyper giant? Or the same peeps who think there’s dark matter or nonsense like a black hole. Oh man, disappointing.

Stars are just lights on the vault ceiling space isn’t real. I’m calling security.

Why is UY Scuti a red supergiant when VY Canis Majoris is a red hypergiant? VY Canis Majoris is smaller (on average) than UY Scuti. Are they classified by mass and not size?

What are your graphics settings?

Can you do a beginners class? i need to know what this genius is saying!

Its crazy how someone can program a system to generate the who entire universe and every single start that you can to up to! It’s crazy. BTW good video like always.

So does uy scuti have stable mass?

but why they look like that?

What if I said that one’s entire life had been decided by fate? That every single one of your actions, from the minute to the monumental, stemmed not from your own choices, but had already been decided upon? That life being a journey of limitless possibilities was but an illusion, and no matter how fiercely man struggled, he stood at the mercy of a long-established path? The wealthy shall know their riches. The needy shall starve on the streets. The wicked shall be wicked, the righteous just. The beautiful, the hideous, the strong, the frail, the fortunate, the miserable… and finally, the victors and the defeated. What if I said that all such things had been carved into stone eons ago, allowing for no divergence? If so, sinners have nothing to answer for, nor do saints have any true virtue to their name. What if I said that not a single action is carried out of one’s own volition, but had been decided long ago? That we are merely adrift in the current of time? Tell me, would you feel content with such a world? A world in which power is merely given, not earned – would you accept knees bent to a throne build upon such falsities? A universe where the sinless have-nots are oppressed and downtrodden – would you allow such a world to exist?
Never, I say. Never.
Those in possession of such knowledge who can still laugh joyfully, oblivious to what it means to be truly alive, are but slaves, the lowest of the low, hardly deserving to be called human beings. Nothing dampens the spirit like the stale wine of an unearned victory. Nothing is more unbearable than bitter defeat against the chains of destiny. Should ceaselessly repeating this farce – this slander of the highest order – be the fate of mankind, then I will struggle against those chains with all my might. I shall walk this road to its utmost conclusion, and, at the distant place I can call my finale, compose an opera that belongs only to me.
And so, I require your aid, my dear ladies and gentlemen. You, the oppressed, the downtrodden, the massacred – you who where once as brethren. You where born to be defeated, to be massacred till the end of times. Should you curse that fate of yours, come and stand at my side as comrades. If a hundred battles yield no victory, fight a thousand. If a thousand battles yield no victory, fight ten thousand. Vow to struggle for an eternity, ceaselessly, till the light of victory finally shines upon you. Any that has the strength to do this shall be permitted to become a means to that end – a part of the “sorcery”. All in order to claim eternal victory. The Mane of the Beast, each an every strand of it, shall be from your flesh and blood. You are blessed to be as such. Although I, you, and he as well… are still bound by that miserable cycle at this moment… let us believe that the decision we are about to make truly holds a meaning… That one day, we can break free from this perpetually repeating cycle.
My dear ladies and gentlemen. Defeated souls of the present age. I await your answer:
Will you rise to battle?

i’m pretty sure stars don’t look like that…. we have technology that allows us to see stars shape because it cancels out a huge majority of the light and severely dims the remaining amount of it… and they are shown to be a sphere… this is real data from our own sun and other suns too.. also most suns don’t have an actual color because when your out in space they look like a ridiculously white ball of blazing light. google that. also its earths atmosphere that makes suns look like they have color.
also i’m not exactly sure where people got this weird info about suns being chaotic and formless, this is like… old timey science theory again, “suns are just clouds of fire.”
why to people jump to theories more than they do fact and truth, facts and truth and hard data that we have obtained through real solid means and through mind and mental theory junk, but through actual physical things..
people dive to theories almost like its their religion, and its starting to make me think that most modern science especially theoretical science is a religious “science” cult, that worships gods of illogical, chaos, Overthinking, Rejection, Denial, Lies, and their most important god they worship of all, a god of Theory and Schemes.
i don’t fear crazies, but i do worry for this world and what you might end up doing to it, with your obsessions and far too unreasonable jumps and wild inquiries about things we cant even access yet.
save thinking about something for when we have the ability to finally access the thing, that way when we actually do get to studying it fully, we arn’t harmed by the previous assumptions that your people made about it, you understand that all it takes is once dingus to make a theory about something that is ending up accepted as fact by your stupid cult, and the next thing you know, the entire safety of earth is at stake.
its most likely going to be through contact with a foreign parasitic organism that takes over its hosts.. because “ohhh this planet was decided that it didn’t have life on it because our cult ancestors said it wasn’t alive or habitable and we accepted it as fact despite it being just a theory because that’s what we do…”
because that is what you do, you replace fact with theory and make theory take the meaning of fact for some twisted backwards reason, but that’s what cults do, even though theory is the exact opposite of fact… your cult will go that 10,000 miles and accept any theory as fact, because to you, theory is fact, and that is very dangerous.. but considering the gods your cult worships, its not very surprising that you don’t care.
the worst part is you probably don’t even realize your part of a cult…that or your just too far gone, into the ideals and manipulation and brainwashing, that your mind that you cant even tell right from wrong… or fact from fiction.. every time one of your gods saints makes a new theory you pounce on it without hesitation.


How big is our Sun?

How big is our Sun? How big can stars get? Above: red supergiant UY Scuti size comparison to the sun.

UY Scuti has a radius 1,700 times that of our sun! Image credit Philip Park via Jillian Scudder/wikimedia

In terms of physical size UY Scuti, has a radius more than 1,700 greater than the sun, but it’s only 30 times the sun’s mass.

The heaviest star is R136a1, 265 times more massive than our sun.

Left to right: a red dwarf, the Sun, a blue dwarf, and R136a1. R136a1 is not the largest known star in terms of radius, only in mass and luminosity. Image credit wikimedia.

More about star sizes, here and here.

UY Scuti is a bright red supergiant or hypergiant and pulsating variable star in the constellation Scutum. It is a leading candidate for being the largest known star. It is also one of the most luminous and well-known of its kind. It has an estimated average median radius of 1,708 solar radii, or a diameter of 2.4 billion km (1.5 billion mi 15.9 AU) thus a volume 5 billion times that of the Sun. It is approximately 2.9 kiloparsecs (9,500 light years) from Earth, making it one of the nearest known hypergiants. If placed at the center of the Solar system, its photosphere would engulf the orbit of Jupiter, although the radius is not known for certain and may be larger than the orbit of Saturn.


What is the Hottest Star?

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Stars can range in temperature, from the relatively cool red dwarfs to superhot blue stars. So what is the hottest star in the Universe?

First, let’s talk a bit about temperature. The color of a star is a function of its temperature. If a star looks red, that means its surface temperature is approximately 2,500 Kelvin. Just for comparison, our Sun, which actually looks white from space, measures about 6,000 Kelvin. The hotter the star, the further up the spectrum you go. The hottest stars are the blue stars. A star appears blue once its surface temperature gets above 10,000 Kelvin, or so, a star will appear blue to our eyes.

So the hottest stars in the Universe are going to be a blue star, and we know they’re going to be massive. So the question is, how massive can stars get? One example is the star Rigel, in the constellation Orion. Rigel is thought to have 17 times the mass of the Sun, and puts out 40,000 times the luminosity of the Sun. It’s surface temperature is a mere 11,000 Kelvin. Another star in Orion, Bellatrix, has a temperature of 21,500 Kelvin. That’s even hotter.

But the hottest known stars in the Universe are the blue hypergiant stars. These are stars with more than 100 times the mass of the Sun. One of the best known examples is Eta Carinae, located about 7,500 light-years from the Sun. Eta Carinae could be as large as 180 times the radius of the Sun, and its surface temperature is 36,000-40,000 Kelvin.

Just for comparison, 40,000 Kelvin is about 72,000 degrees F.

So it’s the blue hypergiants, like Eta Carinae, which are probably the hottest stars in the Universe.

We have written many articles about stars on Universe Today. Here’s an article about how Eta Carinae is almost ready to explode as a supernova. And here’s a link to a nice photo of the nebula around Eta Carinae.

We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful: Episode 12: Where Do Baby Stars Come From, and Episode 13: Where Do Stars Go When they Die?


The Hottest Star

When people talk about the temperatures of stars, we usually are referring to the surface temperature. The surface temperature is way cooler than the believed temperature of the core. Its believed/calculated because no one is ever going to be able to get inside a star and measure one. The temperature at the core of our star, the Sun can reach to about 25 million degrees. Temperatures inside stars could reach four times.

If you happened to have come here because you was looking for the hottest actor or actress in the world then you've come to the wrong place. If you want my answer, its subjective and its in the eye of the beholder and who you think is not necessarily who someone else thinks. Best to go elsewhere.

Does size matter in star temperatures?
Being a large start does not mean it is the hottest star, The largest known star is UY Scuti which is a massive 1,708 times times larger than our Sun but is cooler than our Sun. UY Scuti is only 3,365 K compared to our sun at 5,778 K. The reason for the difference is that the Suns' gravity is holding the Sun in and thereby causing the Sun's atoms to hot up.

Smaller stars are not necessarily hotter, the closest star to our solar system, Proxima Centauri is a red small red dwarf star whose temperature is about 3,042K, not far off the temperature of UY Scuti.

Colours of Stars
The temperatures of the stars follow the colours of the rainbow, (Red, Orange, Yellow, Green, Blue, Indigo, Violet). The coldest stars are red and the hottest stars are blue.

Green Stars
You might what might be a mistake with the diagram, there's green and there's no green stars. There are technically green stars but we can't see them. Stars give off a range of colours rather than one specific colour. Green being slap bang in the middle will be polluted by other colours and not appear green, in fact they'll appear white because of light pollution. Our Sun although it looks yellow in the sky, it looks white in space could really be a green star if it only gave off line in one colour.

Why not all stars are white is because for example, blue stars are on the edge of the spectrum so there's not much to pollute and affect the colour. The same goes with red stars as they are on the end of the scale. There are no invisible stars such as Infra-red or Ultra-violet because they're polluted by other colours to be visible.

Life of a Hot Star
The hotter a star is, the shorter it lives. A star that is cool and small is more energy efficient and will live many times longer than a hotter larger star. Proxima Centauri will still around long after our star has exploded in a supernova explosion. Our Star will around for longer than say Regulus which is a large hot blue star.

Hottest Star Candidates
WR 102
WR 102 is a Wolf-Rayet star, an extremely hot star that is nearing its death. It has passed the main sequence of its life. The Main Sequence is the part of a stars life in which it has finished burning/converting hydrogen into helium. A Wolf-Rayet star has blown off its hydrogen atmosphere and progresing to the next stage. wolf-rayet stars are rare, there are only two stars that can be seen by the naked eye, Regor and Theta Muscae. All the others are too far to be visible including WR 102.

WR102 is about 210,000 Kelvin temperature. It is one of three stars that have a temperature of 200,000 or more. The other being WR 142 in Cygnus and LMC 195-1 in The Large Magellanic Cloud, a satellite galaxy. All three are Wolf-Rayet stars.

Neutron Star
When a star has died, it will either become a black hole or a neutron star depending on its size and mass before it exploded. A Neutron star is the result of the death of a small - medium star whereas anything larger could create a black hole. Neutrons are atoms without electrical charge. A Neutron Star could be nothing larger than the size of Manhatten Island but a teaspon of the stuff would weigh the same amount as a house. Neutron stars can reach temperatures of over 100 billion to a trillon. Quora

Hadar (Beta Centauri)
Based on the Hertzsprung-Russel diagram that you can find elsewhere, one of the hottest stars out there is Hadar which is also known as Beta Centauri in the constellation of Centaurus. It has an estimated temperature in excess of 30,000 K, which is about five times more than our own Sun.

Although Alpha Centauri is the second closest star to us, Hadar is a long way away, it is 525 light years from us compared to that of Alpha Centauri which is a mere 4.32 light years. The only heat we get is from our own Sun.

Interesting Sun's Temperature Fact
The temperature of the Sun is about 5.7K but the corona of the Sun reaches to a few million degree less 500 miles from the photosphere. Scientists have yet to work out the reason why this happens.