April 18, 2012
Mysterious Dark Matter Becomes More Mysterious
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According to a new study, large amounts of dark matter do not surround the Sun, despite some widely accepted theories.
Some scientists believe that the Sun is accompanied by dark matter, which is an invisible substance that can only be detected indirectly by the gravitational force its exerts.
Theories predict that the average amount of dark matter in the Sun's part of the galaxy should be in the range of .88-pounds to 2.2-pounds of dark matter in a volume the size of the Earth.
However, a team of scientists from Chile have discovered that these theories do not fit the observational facts.
A team using the MPG/ESO telescope at ESO's La Silla Observatory has mapped the motions of over 400 stars up to 13,000 light-years from the Sun.
The researchers have calculated the mass of material in the vicinity of the Sun, in a volume four times larger than ever considered before.
“The amount of mass that we derive matches very well with what we see – stars, dust and gas – in the region around the Sun,” team leader Christian Moni Bidin said in a press release. “But this leaves no room for the extra material – dark matter – that we were expecting. Our calculations show that it should have shown up very clearly in our measurements. But it was just not there!”
Astronomers currently believe that dark matter constitutes about 80 percent of the mass in the Universe, but all attempts to detect it in laboratories on Earth have failed.
The new results suggests that attempts to detect dark matter on Earth by trying to spot the interactions between dark matter particles and "normal" matter are unlikely to be successful.
The researchers now suggests that if dark matter does exists on Earth, it would measure just between 0-pounds to .15 pounds in volume.
“Despite the new results, the Milky Way certainly rotates much faster than the visible matter alone can account for," Moni Bidin said. "So, if dark matter is not present where we expected it, a new solution for the missing mass problem must be found.
He said his team's results contradict the currently accepted models, and that "the mystery of dark matter has just become even more mysterious."
The research will be published in The Astrophysical Journal.
Image Caption: This artist´s impression shows the Milky Way galaxy. The blue halo of material surrounding the galaxy indicates the expected distribution of the mysterious dark matter, which was first introduced by astronomers to explain the rotation properties of the galaxy and is now also an essential ingredient in current theories of the formation and evolution of galaxies. New measurements show that the amount of dark matter in a large region around the Sun is far smaller than predicted and have indicated that there is no significant dark matter at all in our neighborhood. Credit: ESO/L. CalÃ§ada