Extending a cosmic yardstick
WASHINGTON — A longer cosmic yardstick promises to give astronomers a better grasp of how fast the universe is expanding and may offer clues to the nature of dark energy, the mysterious entity that accelerates that growth. New measurements based on intense radio-wave emissions peg the distance to the galaxy NGC 6264 at 450 million light-years with an accuracy of 9 percent, giving a look nearly three times farther into the universe than ever before. Previous measurements used a two-step, indirect method that is more error-prone, notes James Braatz of the National Radio Astronomy Observatory in Charlottesville, Va. He reported the finding on February 19 at a meeting of the American Association for the Advancement of Science. —
Probing quark substructure
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WASHINGTON — Like nested Russian dolls, atomic nuclei are made of neutrons and protons and those particles in turn are made of quarks. But if quarks are made of smaller particles, the constituents are no larger than 60 trillionths of a billionth of a meter in diameter. That new limit, about 60 percent smaller than the previous estimate, is based on experiments at the Large Hadron Collider, near Geneva, Switzerland. Additional collider data already recorded should reveal any quark subunits larger than about half the size of the new limit, Thomas LeCompte of the Argonne National Laboratory in Illinois reported February 20 at a meeting of the American Association for the Advancement of Science. —
Downsizing distant black holes
Supermassive black holes at the centers of distant galaxies, previously estimated to range in mass between 10 million to 1 billion suns, may weigh about one-half to one-tenth as much, astronomers from the University of Göttingen in Germany report in the Feb. 17
. The downsizing indicates that black holes in distant and nearby galaxies weigh about the same, eliminating what had been a puzzling mismatch. The researchers base their findings on a new analysis of light emitted from the centers of 37 remote galaxies suspected of harboring supermassive black holes. —
New twist on solar explosions
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New images provide the first direct evidence that giant clouds of charged particles hurled from the sun get twisted and diverted from a straight-line path as they speed through the sun’s outer atmosphere. Documenting the twisting will help to better predict the direction of travel of the billion-ton clouds and whether they will strike Earth, harming power grids and communications systems. Claire Foullon of the University of Warwick in Coventry, England, and her colleagues describe their findings, from NASA’s Solar Dynamics Observatory, in the March 1
Astrophysical Journal Letters
Moon enigma solved
A nearly 40-year-old scientific conundrum has been solved with the discovery of how hydrogen escapes the lunar surface. Protons from the solar wind hit the moon and interact with the moon’s surface to form hydrogen, but scientists hadn’t known how they managed to zoom out again. Recent observations from the IBEX, Chandrayaan and Kaguya spacecraft suggest that the hydrogen is reflecting off the moon’s surface at top speed, Richard Hodges of the University of Colorado at Boulder notes in a paper in an upcoming
Geophysical Research Letters
. That speediness could explain why the Apollo 17 mission didn’t see hydrogen in the lunar atmosphere in 1972. —