University of Central Florida
12/16/2025 | Press release | Distributed by Public on 12/16/2025 08:33
UCF Scientist’s Finding Sheds Light on Milky Way Mystery
A team of astronomers, led by UCF experimental radio astrophysicist Anish Roshi, made a significant observational breakthrough recently published in The Astronomical Journal that could provide clues to our understanding of the energy flow and physical conditions across the Milky Way.
Their discovery in the Cygnus X region sheds new light on and deepens a long-standing mystery about the ionization state of the interstellar medium - the sparse material that fills the space between stars within a galaxy. This is crucial to understanding galactic evolution.
Using the 100-meter Green Bank Telescope in West Virginia, the team detected radio spectral lines from helium in diffuse ionized gas in the Cygnus X region, a massive star-forming complex located about 25,000 light-years from the galactic center.
"We are still investigating. This can provide a better understanding of how energy flows from stars to the interstellar medium in the inner region of the galaxy works," says Roshi, who has served in a few of the world's most advanced observatories over his 20-year career.
A Decades-Old Galactic Puzzle
According to the Big Bang theory, hydrogen and most of the helium in the universe were created in the moments after the initial cosmic event.
Ionization is the process where energetic radiation (like UV light or cosmic rays) or extreme heat strips electrons from neutral atoms or molecules, turning them into charged particles. This ultimately is what makes nebulae visible and is fundamental to understanding stellar life cycles and galactic structure.
For more than 30 years, astronomers have struggled to explain why specific wavelengths of light known as helium spectral lines are faint or missing in the diffuse ionized gas in the inner Milky Way, even though massive stars there produce more than enough high-energy radiation to ionize both hydrogen and helium.
"This has been a persistent mystery," says Pooja Priyatharsheni, second author of the study and a doctoral student at India's Lady Doak College, whom Roshi connected with two years ago while promoting astronomy to collegiate students in India. "We know the galaxy contains plenty of massive stars capable of ionizing helium, yet in many inner regions, we simply don't see the helium signal we expect."
Collaborating across continents: UCF Professor Anish Roshi (right) discusses the discovery of helium radio emission in the Cygnus X region with Lady Doak College doctoral student Pooja Priyatharsheni (center) and another Lady Doak College colleague (left).Cygnus X Provides a Clue - and a Challenge
The new detection in Cygnus X demonstrates that helium within the diffuse gas associated with this region is fully ionized.
"This result confirms that when the radiation field is strong enough, helium becomes fully ionized and visible in radio observations," Priyatharsheni explains. "But it also raises new questions about why the same doesn't occur in the inner galaxy."
What's Next
Led by Roshi of the Florida Space Institute at UCF, researchers from the Green Bank Observatory, the National Radio Astronomy Observatory, West Virginia University and Lady Doak College are now analyzing new high-sensitivity data from the Green Bank Telescope targeting the inner galaxy.
Their goal: to determine whether unusual radiation sources, interstellar dust absorption, or unknown processes might explain the missing helium emission in the inner galaxy.
Their findings will better inform other astrophysicists and aerospace scientists about the energy flow through the interstellar medium and physical conditions of the galaxy, allowing them to refine their research and observational strategies.
They hope to retrieve most of the data for their next findings by the end of 2026.
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