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Rare Carbonaceous Dust Common In Milky Way Found 11 Billion Light-Years Away

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A rare type of cosmic dust unique to the Milky Way has been found in huge concentrations in a galaxy several billion light-years away.

An international team of researchers has discovered that carbonaceous dust, a type of interstellar dust that is scarce in other galaxies, is abundant in a galaxy found 11 billion-light years from Earth.

The uncommon find will help scientists understand how this type of dust forms in the Milky Way and the role it plays in the formation and evolution of stars and planets.

Dust In Galaxies

Dust grains are made from carbon, silicon, aluminum, iron, and a host of heavy elements. Dust comprises only 1 percent of the entire mass of the space between the stars, but it is an integral galactic component nonetheless.

For one thing, stars are born in clouds of dust and gas. The grains of dust found in the birthing space of a star act as a catalyzing agent that prompts the chemical reactions that form a star. For instance, two hydrogen atoms would not normally bind to each other unless they are both bound to the sticky surface of a dust grain.

Dust can also absorb or reflect light, which makes it essential in determining how light from a star travels to distant parts of space.

By studying how dust is formed and where it comes from, researchers gain deep insight into the big astronomical questions, such as how stars and galaxies are formed and, ultimately, how the universe was shaped to what it is today.

How To Measure Interstellar Dust

By looking at gamma-ray bursts coming from a distant star, the researchers led by astronomer Tayyaba Zafar of the Dark Cosmology Centre in the Niels Bohr Institute in Copenhagen and the Angle Australian Observatory were able to analyze the components of dust surrounding the star.

Gamma-ray bursts are extremely bright energetic explosions that can happen between a few milliseconds to a few seconds. They are often found in the wake of a star explosion before the star collapses into a super-dense object in the sky.

By using an array of highly sophisticated telescopes, the researchers were able to detect a gamma-ray burst in a distant galaxy and measure the concentration of dust.

In particular, they studied the gamma-ray burst called GRB180325A, which was first detected on March 28 by NASA's Neil Gehrels Swift Observatory, a mission designed to detect gamma-ray bursts from distant galaxies.

Minutes after Swift detected the gamma-ray burst, University of Iceland PhD researchers Kasper Heintz turned on the Nordic Optical Telescope at Roque de los Muchachos Observatory in the Canary Islands to observe the signal.

He found that GRB180325A traveled the course of 11 billion light-years. He also found that the galaxy where the gamma-ray burst came from had a dust bump similar to that of the Milky Way. A dust bump is a high concentration of dust with the same components.

"Our spectra show that the presence of atomic carbon seems to be a requirement for the dust that causes the dust bump to be formed," Heintz says.

The gamma-ray burst was also observed through the European Southern Observatory's Very Large Telescope in Chile. Both observations reveal the same dust bump from the afterglow of star explosion.

The study is published in the Astrophysical Journal Letters.

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