Chemical Cartography Reveals the Spiral Arms of the Milky Way

Monday - July 24 2023, 01:38 UTC - 1 year ago

Research studying the Milky Way using chemical mapping has yielded a map showing the spiral arms in the Milky Way. It uses the technique of metalicity to measure the ratio of metals to hydrogen and uses data from the LAMOST telescope and the Gaia satellite telescope. The technique can be useful in determining the positions of stars and planets, as well as providing more information about our galactic home.

A researcher has used the technique of chemical mapping to study the spiral arms of our home galaxy: the Milky Way. According to Keith Hawkins, assistant professor at The University of Texas at Austin, chemical cartography might help us better grasp the structure and evolution of our galaxy. "Much like the early explorers, who created better and better maps of our world, we are now creating better and better maps of the Milky Way," mentioned Hawkins in an official release.

Mapping the Milky Way .

By calculating the presence of young stars, such maps can be generated. According to the statement, the number of young stars in a specific area may predict the existence of the Milky Way arm. The light emitted by such young stars allows astronomers to find them. Chemical cartography, on the other hand, can be employed in some regions when the view of the stars is hindered by cosmic dust.

Chemical mapping uses an astronomical concept known as metallicity, which detects the "ratio of metals to hydrogen" present on the surface of a star. Young stars are considered to have a higher metal content than older stars. This implies that young stars will have a greater metallicity as well.

"In theory, the Milky Way’s spiral arms, which contain an abundance of young stars, should have a higher metallicity than the regions between them," noted the release.

Hawkins created his map using the concept of metalicity. He particularly examined a region around the Sun roughly 32,600 light-years wide. The young stars’ data came from the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) and the Gaia satellite telescope. He created the map based on the theory that metal-rich objects should line up with spiral arms, while those with less metal should fill the spaces in between the arms. When he compared his map to others of the same area of the Milky Way, the existence of spiral arms, as predicted, lined up.

Applications of this technique .

"A big takeaway is that the spiral arms are indeed richer in metals. This illustrates the value of chemical cartography in identifying the Milky Way’s structure and formation. It has the potential to fully transform our view of the Galaxy," said Hawkins.

Creating chemical maps may provide useful information about the distribution of elements across the Milky Way. This, in turn, may aid in determining the positions of numerous astronomical objects, such as stars and planets, depending on their chemical composition.

Because we are located inside the Milky Way, astronomers have a limited view of it, making it difficult to explore those far-reaching spiral arms. "It’s like being in a big city. You can look around at the buildings and you can see what street you’re on, but it’s hard to know what the whole city looks like unless you’re in a plane flying above it," explained Hawkins. Hawkins believes that with the advent of advanced telescopes, scientists will be able to generate a more exact and sophisticated chemical mapping of the galaxy.

The findings are published in the journal Monthly Notices of the Royal Astronomical Society. Study abstract: Chemical Cartography, or mapping, of the Milky Way is a powerful tool for investigating our cosmic home. Using metal abundances in young stellar populations as a tracer, we study the structure of the Milky Way. We find evidence for the presence of spiral arms in the targets studied, from the inner Galaxy–starring LAMOST and Gaia data–to the farthest reaches of the Milky Way.