Rethinking galactic origins: Heavy-element mapping challenges conventional theory

Challenging a 20-year-old theory.


IVCs, or intermediate-velocity clouds, are unique space clouds distinguished by their rapid motion. Thousands of light years above the Milky Way, they float. Because they contain the material that makes up planets and stars, these clouds are significant.

According to conventional wisdom, elements are sent back into space when stars burst into massive explosions known as supernovae. These components blend in with the clouds. These nuclear reactions and explosions that occur in our galaxy are the source of the heavy metals found in IVCs.

Using a dust map by the Planck satellite and a map of radio waves emitted from hydrogen, researchers at Nagoya University in Japan discovered that IVCs have much lower heavy elements than previously reported. This novel study into the origins of intermediate-velocity clouds (IVCs) casts doubt on a theory that has been around for twenty years and heralds a new era in deep-space exploration.

Researchers have created the first accurate map detailing the distribution of heavy element abundance in gas clouds falling into the Galactic Plane. The researchers were shocked to discover that the heavy element abundance in the IVCs varied from that of earlier models after examining IVCs and high-velocity clouds. Their finding casts doubt on the conventional Galactic Fountain Model, a theory that explains how gas cycles around our galaxy.

Takahiro Hayakawa from Nagoya University said, “The Galactic Fountain model describes the cycle of gas being blown out from the Galactic Plane by events like supernova explosions and then falling back, similar to how a fountain continuously reuses water. Researchers often cite the model for explaining IVCs because they believed these clouds to have metallicities similar to those of the stars that supposedly produced them.”

The term “metallicity” describes the abundance of heavy elements such as oxygen and iron in stars and galaxies. The research discovered that the metallicities of Intermediate-velocity clouds (IVCs) are far lower than anticipated, indicating their extragalactic origin.

Precise measurements and copious amounts of data were obtained by the researchers through the use of sophisticated procedures and data from the Planck satellite. A long-standing mystery regarding the age and metallicity of ancient stars close to the Sun may be resolved with the aid of this research.

Further research into the expansion and evolution of our galaxy over billions of years may result from these results. It also provides information on the evolution of other galaxies in the universe.

Journal Reference:

  1. Takahiro Hayakawa, Yasuo Fukui. Dust-to-neutral gas ratio of the intermediate- and high-velocity H I clouds derived based on the sub-mm dust emission for the whole sky. Monthly Notices of the Royal Astronomical Society. DOI: 10.1093/mnras/stae302