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Showing posts with label galaxies. Show all posts
Showing posts with label galaxies. Show all posts

Wednesday 22 July 2015

Dead galaxies in Coma Cluster may be packed with dark matter



New computer simulations show that these galaxies stopped star formation as early as 7 billion years ago but haven’t been ripped apart due to their dark matter.

Galaxies in a cluster roughly 300 million light-years from Earth could contain as much as 100 times more dark matter than visible matter, according to an Australian study.

The research used powerful computer simulations to study galaxies that have fallen into the Coma Cluster, one of the largest structures in the universe in which thousands of galaxies are bound together by gravity.

It found the galaxies could have fallen into the cluster as early as 7 billion years ago, which, if our current theories of galaxies evolution are correct, suggests they must have lots of dark matter protecting the visible matter from being ripped apart by the cluster.

Dark matter cannot be seen directly, but the mysterious substance is thought to make up about 84 percent of the matter in the universe.

Cameron Yozin from the University of Western Australia, who led the study, says the paper demonstrates for the first time that some galaxies that have fallen into the cluster could plausibly have as much as 100 times more dark matter than visible matter.

Yozin says the galaxies he studied in the Coma Cluster are about the same size as our Milky Way but contain only 1 percent of the stars.

He says the galaxies appear to have stopped making new stars when they first fell into the cluster between 7 and 10 billion years ago and have been dead ever since, leading astrophysicists to label them “failed” galaxies.

This end to star formation is known as “quenching.”

“Galaxies originally form when large clouds of hydrogen gas collapse and are converted to stars; if you remove that gas, the galaxy cannot grow further,” Yozin said.

“Falling into a cluster is one way in which this can happen. The immense gravitational force of the cluster pulls in the galaxy, but its gas is pushed out and essentially stolen by hot gas in the cluster itself.

“For the first time, my simulations have demonstrated that these galaxies could have been quenched by the cluster as early as 7 billion years ago.

“They have, however, avoided being ripped apart completely in this environment because they fell in with enough dark matter to protect their visible matter,” Yozin said.

Source : Astronomy Magzine

Wednesday 11 February 2015

Hubble Captures 'Happy Face' of Universe

A smiling lens

Hubble Takes a Amazing Picture which seems like Happy Face in the Space.

Of course, this is neither a miracle nor a edited picture.

The reason behind this 'Happy face' is very Complex Phenomena called Gravitational Lensing. The Eyes of the face are two Galaxies but Face's smile is due to gravity. Gravitational lensing is one of the most fascinating thing in Physics and astronomy.

This picture shows the true power of gravity. The gravity of these massive galaxies are so intense that they even distort the space-time create this amazing lens effect. The light itself distorted and gives the magnified view of galaxies.

Some astronomer believes that it is because of Dark matter, an unknown matter which is yet to be discover. These images are the strong evidence of dark matter but further research and experiments are needed to entirely prove their existence.

Hubble takes many images which shows gravitational lensing

hubble-abell-gravitational

Monday 26 January 2015

Wormhole to another galaxy may exist in Milky Way



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(Click Image to Download)

A giant doorway to another galaxy may exist at the centre of the Milky Way, a study suggests.




Scientists believe that dark matter at the centre of our galaxy could sustain a wormhole that we could travel through.




Wormholes are areas where space and time are being bent so that distant points are now closer together.




Einstein predicted them in his theory of General Relativity but nobody knows how they could be held open so that someone could travel through. Most scientists believe that It is extremely unlikely they could exist naturally in the universe. It would take a huge mass, like a Neutron star, to create a bend in time which could bend space time enough to meet another tunnel on the other side. No natural examples have ever been detected.

"If we combine the map of the dark matter in the Milky Way with the most recent Big Bang model to explain the universe and we hypothesise the existence of space-time tunnels, what we get is that our galaxy could really contain one of these tunnels, and that the tunnel could even be the size of the galaxy itself," said Professor Paulo Salucci.

"But there's more. We could even travel through this tunnel, since, based on our calculations, it could be navigable. Just like the one we've all seen in the recent film 'Interstellar"'.

He said the research was surprisingly close to what was depicted in director Christopher Nolan's movie, for which theoretical physicist Kip Thorne provided technical assistance.

"What we tried to do in our study was to solve the very equation that the astrophysicist 'Murph' was working on," said Prof Salucci. "Clearly we did it long before the film came out."

Wormhole, conceptual artwork

 Wormholes bend space-time to allow distant regions to meet


Any wormholes existing in nature have previously been assumed to be microscopic pinpricks in the fabric of space-time.

But the one possibly lying at the centre of the Milky Way would be large enough to swallow up a spaceship and its crew.

Prof Salucci added: "Obviously we're not claiming that our galaxy is definitely a wormhole, but simply that, according to theoretical models, this hypothesis is a possibility."

Other "spiral" galaxies similar to the Milky Way - like its neighbour Andromeda - may also contain wormholes, the scientists believe.

Theoretically it might be possible to test the idea by comparing the Milky Way with a different type of nearby galaxy, such as one of the irregular Magellanic Clouds.

In their paper, the scientists write: "Our result is very important because it confirms the possible existence of wormholes in most of the spiral galaxies ..

"Dark matter may supply the fuel for constructing and sustaining a wormhole. Hence, wormholes could be found in nature and our study may encourage scientists to seek observational evidence for wormholes in the galactic halo region."

The theory was published in the journal Annals of Physics.

Source : Telegraph

Saturday 8 November 2014

Half of universe's stars are orphans with no galaxy

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Celestial orphans are relatively small, less massive, cooler than our sun, expert says

New observations from suborbital rocket launches and an orbiting observatory show that as many as half the stars in the universe may be orphans with no galaxy scientists said on Thursday. They found that the dim light these stars produce from the far reaches of the cosmos equals the amount coming from all the galaxies.
'The night sky on a planet around such a star would be profoundly boring and black to human eyes - no other stars, or at least very few, no Milky Way band, only distant galaxies.'                                        - Michael Zemcov, Caltech experimental astrophysicist

The phenomenon of the orphan star has been well known. Astronomers have witnessed tidal streams of stars being stripped away from colliding pairs of galaxies.




The data suggests orphan stars are probably relatively small, less massive and cooler than our Sun, but typical of most stars in the universe, said Caltech experimental astrophysicist Michael Zemcov.


The night sky as seen from Earth is brimming with starlight. But these orphans would be so distant from other stars that a view from one would offer almost complete nothingness.


"The night sky on a planet around such a star would be profoundly boring and black to human eyes - no other stars, or at least very few, no Milky Way band, only distant galaxies. You might be lucky and see your parent galaxy off in the distance like we see Andromeda," Zemcov said.


Zemcov said scientists have traced the origin of galaxies to about 13.2 billion years ago, 500 million years after the Big Bang that created the universe.


"Galaxies have been forming and interacting continuously since then, with a peak in the star formation rate about two billion years after the Big Bang," Zemcov said. "You have enough interactions over enough time, and you end up stripping out a lot of stars."




Source : cbc.ca