Humans might be getting the calcium in their bones from somewhere a bit more cosmic than milk, according to U. California-Berkeley scientists.
A new type of supernova may explain the large amounts of calcium in the universe and in the human body, according to a study published May 20 in the scientific journal Nature.
The supernova, SN 2005E, was originally discovered five years ago by UC Berkeley’s Katzman Automatic Imaging Telescope. It is one of eight known calcium-rich supernovae, according to Alex Filippenko, a UC Berkeley professor of astronomy and one of the study’s 28 co-authors.
Scientists analyzed the light from SN 2005E and found that the explosion could not be explained given what is understood about currently known supernovae.
“The explosion could not be interpreted in the standard context of normal stellar explosions,” Filippenko said in an e-mail. “The observed characteristics differ significantly from those of normal types of supernovae, suggesting that the explosion mechanism was different.”
Supernovae are divided into two classes based on their optical spectra according to Brad Cenko, a UC Berkeley postdoctoral fellow and co-author of the study.
Type 1a supernovae are thought to result from smaller, older “white dwarf” stars that have a small mass, become unstable and release energy that unbinds the star and ejects material at high speeds.
Type II supernovae, also known as core-collapse supernovae, result from the explosion of massive and short-lived stars that leave behind black holes or neutron stars.
Filippenko said the new discovery provides scientists with a more complete understanding of the endpoints of stellar lives.
Initially, the object looked as if it was the explosion of a massive star – similar to core-collapse supernovae – but after detailed analysis, scientists concluded it was the explosion of a white dwarf star, though this star had exploded in a manner different than other exploding white dwarfs.
According to the study, the original star was a white dwarf stealing helium from a companion star until its mass became very hot and dense, causing a nuclear explosion.
According to Filippenko, SN 2005E stands out not only because it does not fit into either of the two classifications of supernovae, but also because it produced an unusually large amount of calcium.
Researchers concluded that about half the mass thrown out of the explosion was calcium, meaning a few occurrences of such supernovae every 100 years could account for the large amounts of calcium in our galaxy and in all life on Earth.
“Although it is a bit early to know for sure, the discovery of SN 2005E could have several broader implications for astronomy,” Cenko said in an e-mail. “The unique nucleosynthetic products from this explosion could help solve some outstanding puzzles regarding observed overabundances of these elements in our galaxy.”
Many of the co-authors of the paper, including Filippenko and Cenko, are involved with the Palomar Transient Factory in conducting a comprehensive exploration of the universe.
“We hope to be able to find further examples of supernovae like SN 2005E, as well as other new and exotic transient phenomena,” Cenko said in the e-mail. “The universe is, after all, full of surprises!”