Like milk, our Milky Way Galaxy and the rest of the universe is fortified with calcium, the stuff of strong bones. In fact, the cosmos contains 50 percent more calcium than previously thought, a new study suggests.
Calcium is a soft metal and the fifth most abundant element in Earth's crust. Organisms depend on it for chemical assistance with muscle contraction, bones and tooth structure, blood clotting, fluid balance in cells, regulating the heartbeat and other processes.
Explosions of massive stars produce and eject lots of heavy elements into space. The building blocks of new stars, planets and life are released during the final moments of these supernova blasts. Iron that aids in producing our red blood cells and the calcium that hardens our bones are made up of atoms that come from these violent outbursts.
Stellar matter ejected from these explosions form swirls of hot gases that surround galaxies. The calcium atoms in the hot gas emit X-rays with a specific wavelength, which can be detected with instruments aboard ESA’s XMM-Newton X-ray observatory.
“The amount of X-ray radiation at that wavelength is related to the real amount of calcium,” said Jelle de Plaa, a researcher at the SRON Netherlands Institute for Space Research.
De Plaa and colleagues looked to distant clusters of galaxies — containing 20 to 30 percent of visible matter — to measure the amount of calcium.
“In clusters, a lot of the supernova products end up in the hot gas,” De Plaa told SPACE.com. "Clusters are in many ways the big cities of the universe."
The researchers compared the amounts of the products expected from theoretical models of supernovae with measurements from XMM-Newton X-ray observatory within 22 galaxy clusters. The observed amounts for seven elements — oxygen, neon, silicon, sulfur, argon, iron and nickel — jibed with theoretical predictions, but the calcium did not match up.
“Since we checked that there was nothing wrong with our measurements, we concluded that the supernova model (theoretical) must be under predicting the calcium abundance,” De Plaa said.
Supernovae explosions happen in every corner of the universe, but their influences can be felt down on Earth.
“If certain types of supernovae indeed produce more calcium, then this means that there must be more calcium in the universe compared to the predictions from the supernova models,” De Plaa said. “Then this is not only true for clusters, but also for our solar system and everything that lives in it, because we are mostly made of the same supernova products.”
The study is detailed in a forthcoming issue of the journal Astronomy & Astrophysics.