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| Two white dwarfs head toward a collision in this artist’s illustration. New research suggests that the Milky Way's preponderance of positrons could come from a specialized type of supernova from colliding low-mass white dwarfs — an explosion that is difficult to detect, but rich in an isotope that generates this kind of antimatter. Credit: NASA/Tod Strohmayer (GSFC)/Dana Berry (Chandra X-Ray Observatory) |
The majority of antimatter that pervades the Milky Way may come from clashing remnants of dead stars, a new study finds.
The work may solve a 40-year-old astrophysics mystery, the study's researchers said.
For every particle of normal matter, there is an antimatter counterpart with the opposite electrical charge but the same mass. The antiparticle of the negatively charged electron, for instance, is the positively charged positron. [Will Antimatter Power the First Starships?]
When a particle meets its antiparticle, they annihilate each other, giving off a burst of energy. A gram of antimatter annihilating a gram of matter would release about twice the amount of energy as the nuclear bomb dropped on Hiroshima, Japan.
More than 40 years ago, scientists first detected that the kind of gamma-rays that are given off when positrons are annihilated were being emitted from all around the galaxy. Their findings suggested that 10^43 positrons — that's a 1 with 43 zeroes behind it — were being annihilated in the Milky Way every second. Oddly, most of these positrons were detected in the galaxy's central bulge rather than its outer disk, even though the bulge hosts less than half of the Milky Way's mass.
Charles Q. Choi
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