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The Universe, And Its Mysteries....
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The Universe, And Its Mysteries....Posted:

Logistics
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THE MYSTERIES OF THE UNIVERSE




Biggest Star In Universe

Before we jump straight to the answer, lets take a look at our own Sun for a sense of scale. Our familiar star is a mighty 1.4 million km across (870,000 miles). Thats such a huge number that its hard to get a sense of scale. The Sun accounts for 99.9% of all the matter in our Solar System. In fact, you could fit one million planet Earths inside the Sun.

Astronomers use the terms solar radius and solar mass to compare large and smaller stars, so well do the same. A solar radius is 690,000 km (432,000 miles) and 1 solar mass is 2 x 1030 kilograms (4.3 x 1030 pounds). Thats 2,000,000,000,000,000,000,000,000,000,000 kg.

One huge, famous star in our galaxy is the monster Eta Carinae, located approximately 7,500 light years away, and weighing in at 100 solar masses. Its 4 million times as bright as the Sun. Most stars blow with a solar wind, losing mass over time. But Eta Carinae is so large that it casts off 500 times the mass of the Earth every year. With so much mass lost, its very difficult for astronomers to accurately measure where the star ends, and its stellar wind begins.

So the best answer astronomers have right now is that Eta Carinaes radius is 400 times the size of the Sun. And as star size estimates go, thats pretty accurate.

And one interesting side note: Eta Carinae should explode pretty soon as one of the most spectacular supernovae humans have ever seen.
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But thats nothing. The largest known star is VY Canis Majoris; a red hypergiant star in the Canis Major constellation, located about 5,000 light-years from Earth. University of Minnesota professor Roberta Humphreys recently calculated its upper size at more than 2,100 times the size of the Sun. Placed in our Solar System, its surface would extend out past the orbit of Saturn. Light takes more than 8 hours to cross its circumference!

Some astronomers disagree, and think that VY Canis Majoris might be smaller; merely 600 times the size of the Sun, extending past the orbit of Mars.

Thats the biggest star that we know of, but the Milky way probably has dozens of stars that are even larger, obscured by gas and dust so we cant see them.

But lets see if we can work out the original question, whats the biggest star in the Universe? Obviously, its impossible for us to actually find it the Universe is a big place, and theres no way we can peer into every corner.
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But according to theorists, how big can stars get?

I contacted Roberta Humphreys from the University of Minnesota, the researcher who calculated the size of VY Canis Majoris, and posed this question to her. She noted that the largest stars are the coolest. So even though Eta Carinae is the most luminous star we know of, its extremely hot 25,000 Kelvin and so only a mere 400 solar radii.

The largest stars will be the cool supergiants. For example, VY Canis Majoris is only 3,500 Kelvin. A really big star would be even cooler. At 3,000 Kelvin, a cool supergiant would be 2,600 times the size of the Sun.

Finally, heres a great animation that shows the size of various objects in space, starting with our tiny planet and finally getting to VV Cephei A. I guess they didnt have the new info on VY Canis Majoris to include it in the animation.




Black Holes

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Inspiring phenomenons in space are the black hole. Black hole facts are searched for every day. Amateur astronomers as well as the professionals often ponder questions related to black holes. So, for the fun of it and because we want to help educate you, we here on Universe Today decided to put together a few black holes facts to intrigue your mind and satisfy a little of your curiosity.

Fact 1

As black hole facts go, this is basic one. A black hole is a place where the gravity well is so great that a gravitational time dilation has occurred. This causes time to stop. This causes an event horizon into which objects can fall or be pulled, but those objects will never reappear. That is the basic definition according to Einsteins theory of general relativity.

Fact 2

There is no limit to how small or how large a black hole can be. The size and mass of a black hole are directly related. The more massive a black hole is, the more space it takes up. In fact, the Schwarzschild radius ( the radius of the event horizon of a black hole) and the mass are directly proportional to one another. Therefore, if one black hole weighs ten times as much as another, its radius is ten times as large. For example, a black hole with a mass equal to that of our Sun would have a radius of 3 kilometers, a typical 10-solar-mass black hole would have a radius of 30 kilometers, and so on.

Fact 3

The nearest black hole is 1,600 light years away. That is about 16 quadrillion kilometers for Earth.

Fact 4

One the interesting black hole facts is that they can not suck up all of the matter in the Universe. Each black hole has its own event horizon, much like the gravitational field of a planet. If matter is not in that horizon it will never get sucked into the black hole.

Fact 5

This one tips the scales on the heavy end as black hole facts go: there is a super massive black hole at the center of the Milky Way galaxy. It weighs in at about 4 million solar masses. Luckily, there is no reason to worry. This giant sucker is over 30,000 light years away.

Fact 6

The last of the black hole facts I have to offer today is that many theorists believe that a black hole can eventually evaporate. How is that? Steven Hawking proposed that black holes were not entirely black. They emit radiation. The energy that produces the radiation comes from the mass of the black hole. As the radiation is emitted, the black hole loses mass. The black hole emits more radiation the smaller it gets. In effect, a black hole evaporates more quickly as it shrinks.




How Big is A Black Hole?

Before you can answer how big is a black hole?, you have to understand exactly what a black hole is. A black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull.

That definition leads you to wonder slightly about gravity. If, for some reason, you throw a rock straight up into the air it will rise for a while, but eventually the acceleration due to the planets gravity will make it start to fall down again. If the acceleration is enough, you could make it escape the planets gravity entirely. It would keep on rising forever. The speed with which you need to throw the rock in order that it just barely escapes the planets gravity is called the escape velocity. As you would expect, the escape velocity depends on the mass of the planet: if the planet is extremely massive, then its gravity is very strong, and the escape velocity is high. A lighter planet would have a smaller escape velocity. The escape velocity also depends on how far you are from the planets center: the closer you are, the higher the escape velocity. The Earths escape velocity is 11.2 kilometers per second and the Moons is only 2.4 kilometers per second. After taking those two facts into consideration, look at a black hole. It is so massive that light does not travel fast enough to escape its gravity. Since nothing known travels faster than the speed of light, nothing can escape a black hole.

Now, back to the original question how big is a black hole?. There are many different ways to describe how big something is. Lets just look at much mass it has and how much space it takes up. There is no limit(in principle) to how much or how little mass a black hole can have. In theory, any amount of mass at all can be made to form a black hole if you compress it to the right density. Most of the black holes were produced by the deaths of massive stars, so scientists believe those black holes weigh about as much as a massive star. A typical mass for such a black hole would be about 10 times the mass of the Sun, or about 1031 kilograms. Astronomers also suspect that many galaxies harbor extremely massive black holes at their centers. These are thought to weigh about a million solar masses.

The more massive a black hole is, the more space it takes up. In fact, the Schwarzschild radius (radius of the event horizon) and the mass are directly proportional to one another: if one black hole weighs ten times as much as another, its radius is ten times as large. A black hole with a mass equal to that of the Sun would have a radius of 3 kilometers. So a typical 10-solar-mass black hole would have a radius of 30 kilometers, and a million-solar-mass black hole at the center of a galaxy would have a radius of 3 million kilometers. Whether you measure by mass or space taken up, black holes can be some of the largest objects in the universe.




First Black Holes May Have Formed in Cocoons

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Very likely, the last image that comes to mind when thinking of black holes is that they need to be nurtured, coddled and protected when young. But new research reveals the first large black holes in the universe likely formed and grew deep inside gigantic, starlike cocoons that smothered their powerful x-ray radiation and prevented surrounding gases from being blown away.

Until recently, the thinking by many has been that supermassive black holes got their start from the merging of numerous, small black holes in the universe, said Mitchell Begelman, from the University of Colorado-Boulder. This new model of black hole development indicates a possible alternate route to their formation.
Ordinary black holes are thought to be remnants of stars slightly larger than our sun that used up their fuel and died.

But the first big black holes likely formed from very large stars that formed early in the Universe, probably within the first few hundred million years after the Big Bang. The unique process of these large stars becoming black holes includes the formation of a protective cocoon, made of gas.

Whats new here is we think we have found a new mechanism to form these giant supermassive stars, which gives us a new way of understanding how big black holes may have formed relatively fast, said Begelman.
These early supermassive stars would have grown to a huge size as much as tens of millions of times the mass of our sun and would have been short-lived, with its core collapsing in just in few million years.

The main requirement for the formation of supermassive stars is the accumulation of matter at a rate of about one solar mass per year, said Begelman. Because of the tremendous amount of matter consumed by supermassive stars, subsequent seed black holes that formed in their centers may have started out much bigger than ordinary black holes.

Begelman said the hydrogen-burning supermassive stars would had to have been stabilized by their own rotation or some other form of energy like magnetic fields or turbulence in order to facilitate the speedy growth of black holes at their centers.

After the seed black holes formed, the process entered its second stage, which Begelman has dubbed the quasistar stage. In this phase, black holes grew rapidly by swallowing matter from the bloated envelope of gas surrounding them, which eventually inflated to a size as large as Earths solar system and cooled at the same time, he said.

Once quasistars cooled past a certain point, radiation began escaping at such a high rate that it caused the gas envelope to disperse and left behind black holes up to 10,000 times or more the mass of Earths sun. With such a big head start over ordinary black holes, they could have grown into supermassive black holes millions or billions of times the mass of the sun either by gobbling up gas from surrounding galaxies or merging with other black holes in extremely violent galactic collisions.

Begelman said big black holes formed from early supermassive stars could have had a huge impact on the evolution of the universe, including galaxy formation, possibly going on to produce quasars the very bright, energetic centers of distant galaxies that can be a trillion times brighter than our sun.




Even Early Galaxies had Super Massive Black Holes

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Were learning more about black holes and the early universe all the time, with the help of all the amazing ground-based telescopes astronomers now have at their disposal. Astronomers think that many perhaps all galaxies in the universe contain massive black holes at their centers. New observations with the Submillimeter Array now suggest that such colossal black holes were common even 12 billion years ago, when the universe was only 1.7 billion years old and galaxies were just beginning to form. The new conclusion comes from the discovery of two distant galaxies, both with black holes at their centers, which are involved in a spectacular collision.

4C60.07, the first of the galaxies to be discovered, came to astronomers attention because of its bright radio emission. This radio signal is one telltale sign of a quasar a rapidly spinning black hole that is feeding on its home galaxy.
When 4C60.07 was first studied, astronomers thought that hydrogen gas surrounding the black hole was undergoing a burst of star formation, forming stars at a remarkable rate the equivalent of 5,000 suns every year. This vigorous activity was revealed by the infrared glow from smoky debris left over when the largest stars rapidly died.

The latest research, using the keen vision of the Submillimeter Array of eight radio antennas located in Hawaii, revealed a surprise. 4C60.07 is not forming stars after all. Indeed, its stars appear to be relatively old and quiescent. Instead, prodigious star formation is taking place in a previously unseen companion galaxy, rich in gas and deeply enshrouded in dust, which also has a colossal black hole at its center.

This new image reveals two galaxies where we only expected to find one, said Rob Ivison (UK Astronomy Technology Centre), lead author of the study that will be published in the Monthly Notices of the Royal Astronomical Society. Remarkably, both galaxies contain supermassive black holes at their centers, each capable of powering a billion, billion, billion light bulbs. The implications are wide-reaching: you cant help wondering how many other colossal black holes may be lurking unseen in the distant universe.

Due to the finite speed of light, we see the two galaxies as they existed in the distant past, less than 2 billion years after the Big Bang. The new image from the Submillimeter Array captures the moment when 4C60.07 ripped a stream of material from its neighboring galaxy, as shown in the accompanying artists conception. By now the galaxies have merged to create a football-shaped elliptical galaxy. Their black holes are likely to have merged and formed a single, more massive black hole.

The galaxies themselves show surprising differences. One is a dead system that has formed all of its stars already and used up its gaseous fuel. The second galaxy is still alive and well, holding plenty of dust and gas that can form new stars.


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#2. Posted:
Austin_Powers
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the world will end when the world ends :trollin: to me I don't give a sh*t when that may be, because were all going to die at the same time.. Not like were leaving family behind or any thing.
#3. Posted:
Logistics
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Austin_Powers wrote the world will end when the world ends :trollin: to me I don't give a sh*t when that may be, because were all going to die at the same time.. Not like were leaving family behind or any thing.

This does not have much to do with it ending.
#4. Posted:
Logistics
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Wow, we started to learn more about this today...wow.
#5. Posted:
Vortensity
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I'd be extremely surprised if this wasn't a copy and paste.

But even if it is, this is the best thing i've saw on the conspiracy board, even though it's not a conspiracy.

+REP from me bro, best post ive saw in a while, very useful for people who are curious about the Universe nd it's mysteries. Althought I know most of this

Good job anyway! Keep it up!
#6. Posted:
Logistics
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Phaeleh wrote I'd be extremely surprised if this wasn't a copy and paste.

But even if it is, this is the best thing i've saw on the conspiracy board, even though it's not a conspiracy.

+REP from me bro, best post ive saw in a while, very useful for people who are curious about the Universe nd it's mysteries. Althought I know most of this

Good job anyway! Keep it up!

Lol, its not all copy pasted. I put my own knowledge in there too :p
#7. Posted:
Human
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mysteries of the universe - why is op a *** and why did you copy/paste all of this?
#8. Posted:
Logistics
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Human wrote mysteries of the universe - why is op a **** and why did you copy/paste all of this?

Its not all Copy pasted, I still edit things in it so, yes it is Copied but with own words.
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RageX503
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I honestly think that a black hole might be something like a teleporter. Maybe brings you to a different part of a universe? I honestly don't know. The universe is plain amazing.
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