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Astronomers Discover Dragonfly 44, a Milky Way–sized Galaxy consisting of 99.99 percent Dark Matter

Dragonfly 44's mass is estimated to be one trillion times the mass of the Sun, which is similar to the mass of the Milky Way

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Little Cub galaxy
The Little Cub galaxy - so called because it sits in the Ursa Major or Great Bear constellation. Galaxy (Representational Image). Wikimedia

New York, August 27, 2016: An international team of astronomers has found a massive galaxy — about the size of the Milky Way — that consists almost entirely of dark matter.

The galaxy, Dragonfly 44, is located in the nearby Coma constellation and had been overlooked until last year because of its unusual composition. It is a diffuse “blob” about the size of the Milky Way, but with far fewer stars, the researchers said.

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“Very soon after its discovery, we realised this galaxy had to be more than meets the eye. It has so few stars that it would quickly be ripped apart unless something was holding it together,” said lead author Pieter van Dokkum from Yale University in New Haven, Connecticut.

Dragonfly 44’s mass is estimated to be one trillion times the mass of the Sun, which is similar to the mass of the Milky Way. However, only one-hundredth of one percent of that is in the form of stars and “normal” matter.

The dark galaxy Dragonfly 44. The image on the left is a wide view of the galaxy. Source: VOA news
The dark galaxy Dragonfly 44. The image on the left is a wide view of the galaxy.
Source: VOA news

The other 99.99 percent is in the form of dark matter — a hypothesised material that remains unseen but may make up more than 90 percent of the universe, the researchers reported in a paper published in the Astrophysical Journal Letters.

Van Dokkum’s team was able to get a good look at Dragonfly 44 thanks to the W.M. Keck Observatory and the Gemini North telescope, both in Hawaii.

Astronomers used observations from Keck, taken over six nights, to measure the velocities of stars in the galaxy.

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They used the eight-metre Gemini North telescope to reveal a halo of spherical clusters of stars around the galaxy’s core, similar to the halo that surrounds our Milky Way galaxy.

Star velocities are an indication of the galaxy’s mass, the researchers noted. The faster the stars move, the more mass its galaxy will have.

“Amazingly, the stars move at velocities that are far greater than expected for such a dim galaxy. It means that Dragonfly 44 has a huge amount of unseen mass,” co-author Roberto Abraham of the University of Toronto, explained.

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2 COMMENTS

  1. A great find by the astronomers in the field of space exploration. After reading about Dragonfly 44, i realised that the Universe have many hidden secrets and that humans will always be curious to explore it.

  2. I’m curious as to what is in the center of the galaxy. Does it also have a supermassive black hole made out of regular matter or is there some equally dense dark matter equivalent of a black hole?

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Researchers Claim The Existence Of Planet Nine

Researchers from an American University have laid evidences to prove the presence of Planet Nine

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Planet Nine
Kuiper Belt indicates the presence of Planet Nine
  • The science communities since a long time have been debating upon the existence of Planet Nine. 
  • Space highlights different shreds of evidence based on which scientists are stating the claim.

What Is Planet Nine?

Planet Nine is a hypothetical planet present in the far outer Solar System, whose mass is estimated to be 10 times more than the mass of Earth. The planet is said to be 20 times farther than the sun than Neptune is.

What Do Researchers Have To Say?

Dr Konstantin Batygin, a planetary astrophysicist at the California Institute of Technology, said that there were five different lines of observational evidence which pointed to the existence of Planet Nine. He stated that if this theory does not sound believable, then people would have to come up with the answers of the five pieces of evidence which could lead to further confusion.

Also Read: Five Students from Telangana Selected for the NASA Human Exploration Rover Challenge

Batygin in 2016 published a study examining the six known objects in the Kuiper Belt, a  circumstellar disc in the Solar System beyond the planets that extends from the orbit of Neptune towards interstellar space.

The study examines all the objects have elliptical orbits pointing in the same direction and are tilted the same way. These serve as evidence to the planet’s existence.

It is being said that the objects are tilted 30 degrees downward compared to the plane where the eight official planets circle the sun. Researchers also made use of computer simulations of the solar system including the Planet Nine and to demonstrate that there should be more objects tilted a whopping 90 degrees to solar plane. It was revealed that five such objects, which fit these parameters were already known.

The study led to the birth of two more ideas. Researchers said that this planet could have tilted the planets of the solar system during the last 4.5 billion years.

Planet Nine’s existence could also tell the reason as to why Kuiper Belt objects orbit in the opposite direction as compared to other things in the solar system.

-Prepared by Megha Acharya of NewsGram.

(the story was originally published in PTI)

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Ultra-High Energy Cosmic Rays Come From Outside The Milky Way

Travelling with a speed of lights, cosmic rays are atomic nuclei. Scientist says that high energy cosmic rays coming from outer space are hitting the earth.

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Cosmic rays
Source: Pixaby

New York, September 24, 2017: Researchers have found that some ultra-high energy cosmic rays that occasionally hit Earth come from a distant source outside the Milky Way.

Cosmic rays are atomic nuclei that travel through space at speeds close to that of light. Low-energy cosmic rays come from the Sun or from our own galaxy, but the origin of the highest-energy particles has been the subject of debate ever since they were first discovered fifty years ago.

Do they come from our Galaxy or from distant extragalactic objects?

The study published in the journal Science demonstrated that those cosmic rays with energies a million times greater than that of the protons accelerated in the Large Hadron Collider – the world’s largest and most powerful particle accelerator – come from much further away than from our own galaxy.

They were detected from 2004 to 2016 at the largest cosmic ray observatory ever built, the Pierre Auger Observatory in Argentina.

“We are now considerably closer to solving the mystery of where and how these extraordinary particles are created — a question of great interest to astrophysicists,” said Karl-Heinz Kampert from University of Wuppertal in Germany.

“Our observation provides compelling evidence that the sites of acceleration are outside the Milky Way,” Kampert who is spokesperson for the Auger Collaboration, which involves more than 400 scientists from 18 countries, said.

Cosmic rays are the nuclei of elements from hydrogen to iron. The highest-energy cosmic rays, those of interest in this study, only strike about once per square kilometre per year — equivalent to hitting the area of a soccer field about once per century.

Such rare particles are detectable because they create showers of secondary particles — including electrons, photons and muons – as they interact with the nuclei in the atmosphere.

These cosmic ray showers spread out, sweeping through the atmosphere at the speed of light in a disc-like structure, like a dinner plate but several kilometres in diameter.

ALSO READ: NASA’s Asteroid-chasing Spacecraft Osiris-Rex Swinging by Earth on Way to Space Rock

At the Auger Observatory, the shower particles are detected through the light they produce in several of 1,600 detectors, spread over 3,000 square kilometres of western Argentina and each containing 12 tons of water.

Tracking these arrivals tells scientists the direction from which the cosmic rays came.

After racking up detections of more than 30,000 cosmic particles, the scientists found one section of the sky was producing significantly more than its share.

The probability of this happening by a random fluctuation is extremely small, the scientists said — a chance of about two in ten million.

“This result unequivocally establishes that ultra-high energy cosmic rays are not just random wanderers of our nearby universe,” Paolo Privitera of University of Chicago who heads the US groups participating in the project, said. (IANS)

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Astronomers Discover New ‘Mid-size’ Black Hole 100,000 Times More Massive than the Sun

Scientists predict that nearly 100 million of these small black holes should exist in the Milky Way, however only about 60 have been found till now

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Black hole in milky way
A near-infrared image of a black hole at the center of the Milky Way galaxy as seen with Hubble Space Telescope/NICMOS. (NASA/STScI) (VOA)
  • Researches in Japan have discovered a super-massive black hole in Milky Way Galaxy
  • The black hole is believed to weigh as much as 400 suns
  • According to studies,  at least 100 million of these small black holes should exist in the Milky Way

Japan, September 5, 2017 : Astronomers have found new evidence for the existence of a mid-sized black hole, considered the missing link in the evolution of super-massive black holes.

Astronomers in Japan found the possible black hole in our own Milky Way galaxy, a long-theorized object which is bigger than the small black holes formed from a single star, but still much smaller than giant black holes such as the one at the center of the Milky Way.

Black holes are difficult to find because they do not emit any light. However, scientists can detect them by their influence on nearby objects.

The astronomers in Japan found new evidence of the so-called intermediate-mass black hole when they turned a powerful telescope in Chile’s Atacama desert on a gas cloud near the center of the Milky Way. The gases in the cloud move at unusual speeds, and the scientists believed they were being pulled by immense gravitational forces. They say the gravitational force is likely caused by a black hole measuring about 1.4 trillion kilometers across.

black hole in Milky way galaxy
Radio telescope antennas of the ALMA (Atacama Large Millimeter/submillimeter Array) project are seen in the Atacama desert, some 1500 km north of Santiago, Chile, VOA

The findings are published in the journal Nature Astronomy.

Theoretical studies predict at least 100 million of these small black holes should exist in the Milky Way, however only about 60 have been found.

The possible mid-sized black hole is much smaller than the super massive black hole that is located in the center of the galaxy, known as Sagittarius A, which weighs as much as 400 million suns.

“This is the first detection of an intermediate-mass black hole candidate in the Milky Way galaxy,” said the study’s leader, Tomoharu Oka from Keio University, Japan.

If confirmed, the intermediate-mass black hole could help explain how supermassive black holes operate. One theory is that supermassive black holes, which are at the center of most massive galaxies, are formed when smaller black holes steadily coalesce into larger ones. However, until now no definitive evidence has existed for intermediate-mass black holes that could indicate a middle step between the small and massive black holes already detected.

Researchers say they will continue to study the intermediate-mass black hole candidate in the hope of confirming its existence. (VOA)