Posted on 10/10/2014 1:00:47 PM PDT by Red Badger
New research from the University of Western Australia reveals that the amount of dark matter in the Milky Way is half as much as previously thought.
Australian astronomers used a method developed almost 100 years ago to discover that the weight of dark matter in our own galaxy is 800,000,000,000 (or 8 x 1011) times the mass of the Sun.
They probed the edge of the Milky Way, looking closely, for the first time, at the fringes of the galaxy about 5 million billion kilometers from Earth.
Astrophysicist Dr Prajwal Kafle, from The University of Western Australia node of the International Center for Radio Astronomy Research, said we have known for a while that most of the Universe is hidden.
“Stars, dust, you and me, all the things that we see, only make up about 4 per cent of the entire Universe,” he said.
“About 25 per cent is dark matter and the rest is dark energy.”
Dr Kafle, who is originally from Nepal, was able to measure the mass of the dark matter in the Milky Way by studying the speed of stars throughout the galaxy, including the edges, which had never been studied to this detail before.
He used a robust technique developed by British astronomer James Jeans in 1915 — decades before the discovery of dark matter.
Dr Kafle’s measurement helps to solve a mystery that has been haunting theorists for almost two decades.
“The current idea of galaxy formation and evolution, called the Lambda Cold Dark Matter theory, predicts that there should be a handful of big satellite galaxies around the Milky Way that are visible with the naked eye, but we don’t see that,” Dr Kafle said.
“When you use our measurement of the mass of the dark matter the theory predicts that there should only be three satellite galaxies out there, which is exactly what we see; the Large Magellanic Cloud, the Small Magellanic Cloud and the Sagittarius Dwarf Galaxy.”
University of Sydney astrophysicist Professor Geraint Lewis, who was also involved in the research, said the missing satellite problem had been “a thorn in the cosmological side for almost 15 years.”
“Dr Kafle’s work has shown that it might not be as bad as everyone thought, although there are still problems to overcome,” he said.
The study also presented a holistic model of the Milky Way, which allowed the scientists to measure several interesting things such as the speed required to leave the galaxy.
“Be prepared to hit 550 kilometers per second if you want to escape the gravitational clutches of our galaxy,” Dr Kafle said.
“A rocket launched from Earth needs just 11 kilometers per second to leave its surface, which is already about 300 times faster than the maximum Australian speed limit in a car!”
Publication: Prajwal Raj Kafle, et al., “On the Shoulders of Giants: Properties of the Stellar Halo and the Milky Way Mass Distribution,” 2014, ApJ, 794, 59; doi:10.1088/0004-637X/794/1/59
PDF Copy of the Study: On the Shoulders of Giants: Properties of the Stellar Halo and the Milky Way Mass Distribution
Image: ESO/L. Calçada
Ya but, have they looked in ALL the universes? Sometimes you can find missing matter in the last place you look.
Makes me think of the Far Side cartoon where there is a large plain with just one tree, and one dinosaur. The dinosaur manages to walk into the tree.
Two hydrogen atoms walk into a bar.
One says, “I just lost an electron!”
The second one says, “Are you sure?”
The first one replies, “I’m positive!”..................
It’s dark, so.....................
That's racist!!
Still awaiting explanation of the GRAVITY, and what it is...............
Since we live in a binary universe, we need to explain how to produce negative gravity. Then off to the stars...
5.56mm
Since gravity is the name of the effect that mass has on the fabric of space-time, depressing it and hence producing a ‘downward’ spiral toward the mass, we need to invent ‘negative mass’ to produce the exact opposite effect, an ‘upward spiral’ away from, or at least raising, the fabric of space-time..............
Bush's fault!
Just the White Man trying to eliminate dark matter.
The Bible sez “He that sittest in the heavens shall laugh. He shall hold them in derision.” That’s the origin of Snickers. HE Snickers...at little pantywaist mortal men who reject His Infallible Word, and instead make up cunningly devised fables....such as macro evolution, big bang theories, etc.
Maybe they should close their eyes.
...or use a flashlight................
Is that Warp one or two?...................
All good questions which have occurred to me as well. In my opinion our current understanding of the actual mechanics of reality is about the same as a dog staring at a ceiling fan. He knows that there's something there but doesn't have a clue just what it is.
With AF-1 continually being airborne it is hard to track!
Here’s another one. Maybe I’m just to stupid but can a photon be stationary next to a specific object? Say a rock, person or tree.
Settled science, don’t you know....
Five million billion kilometers? Holy crap.
That’s pretty far.......................
Believe the post has the theory of a fabulous engine.
Cup size? (for males)
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