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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
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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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  • Kabir Chaudhary

    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.

  • Manakas

    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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  • Kabir Chaudhary

    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.

  • Manakas

    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?

Next Story

India Is Developing Technologies To Launch Manned Mission

The state-run ISRO’s technology demonstrator is the first in a series of tests to qualify as a crew escape system, critical for a manned mission.

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India’s dream to put a man in space
India’s dream to put a man in space. Pixabay

India is developing critical technologies for launching manned missions in space and preparing a document on it, a top official said on Saturday.

“Critical technologies are being developed for our human space programme as it is India’s dream to put a man in space. A mission document is in the making,” Indian Space Research Organisation (ISRO) Chairman K. Sivan told the media at an aerospace event here.

Citing the space agency’s successful maiden unmanned pad abort test on Thursday at its Sriharikota spaceport in Andhra Pradesh for the safe escape of the crew in an emergency, Sivan said that very complex technology was used for the trial, with a unique motor for fast-burning.

“The technology is very essential for our manned missions in the future, as the motor’s performance was very good. Using aerodynamics, the module was turned in a favourable direction to open the parachutes,” he said.

The state-run ISRO’s technology demonstrator is the first in a series of tests to qualify as a crew escape system, critical for a manned mission.

“We are only in the preparation stage. We need to develop much more. We are in the process of refining a document on the manned mission for review and interactions with stakeholders, including the Indian Air Force (IAF) and Hindustan Aeronautics Ltd (HAL),” said Sivan.

The crew escape system is an emergency escape measure designed to quickly pull the crew module along with the astronauts to a safe distance from the launch vehicle in the event of a launch abort.

The first pad abort test demonstrated the safe recovery of the crew module in case of any exigency at the launch pad,” ISRO said in a statement earlier.

Admitting that the scientists had to work on the next strategy for the manned mission testing, Sivan said ISRO’s work was two-pronged, with one on approved projects and the other for research and development (R&D).

The first pad abort test demonstrated the safe recovery of the crew module in case of any exigency at the launch pad,” ISRO said in a statement earlier.
The first pad abort test demonstrated the safe recovery of the crew module in case of any exigency at the launch pad,” ISRO said in a statement earlier. Flickr

“The pad abort test for the crew escape system is part of our R&D work,” he noted. The space agency also tested five new technologies during the pad abort test, as part of its strategy to develop long-term technologies.

“We and the government work on a three-year plan, with a seven-year strategy and a 15-year vision,” asserted Sivan.

Noting that space tourism would happen in the near future, the rocket scientist said it would take at least 15 years to develop the vehicle to go to space and return to the earth.

“We are not close to that. We need to work a lot towards achieving the dream of putting a man into space,” added Sivan.

After a five-hour countdown, the crew escape system lifted off with the 12.6 tonne simulated crew module from the spaceport and plunged into the sea (Bay of Bengal) 4 minutes and 19 seconds later with two parachutes, around 2.9 km away from Sriharikota, about 90km northeast of Chennai.

Also read: NASA Scientists Map Water on Moon Using India’s Chandrayaan-1 Spacecraft!

“The crew module soared 2.7 km altitude on thrust of its seven solid motors without exceeding the safe G (gravity) levels,” added the statement. (IANS)