Astronomers have utilized the Karl G. Jansky Very Large Array (VLA) and the 500-meter Spherical Radio Telescope (FAST) to produce the most detailed radio map of neutral hydrogen surrounding the Orion Nebula. This groundbreaking research reveals vast expanding shells, enigmatic cavities, and elongated filaments, indicating that the renowned stellar nursery was shaped by multiple generations of massive stars rather than a single expanding bubble.
The detailed Orion Nebula shell depicted in HI radiation from VLA and FAST observations (shown in red), Hα radiation from the European Southern Observatory’s Digitized Sky Survey (shown in green), and 3.4 μm radiation captured by the WISE satellite (shown in blue). Image credit: Juan D. Soler, University of Vienna / NRAO / VLA / NASA / WISE.
The Orion Nebula, located 1,350 light-years away in the constellation Orion, is a diffuse nebula known for its astronomical significance.
Also referred to as NGC 1976, Messier 42, M42, LBN 974, and Sharpless 281, the Nebula spans approximately 24 light-years in length.
Visible to the naked eye, it appears as a hazy spot near the star Theta Orionis, below Orion’s belt.
At an age of just 2 million years, the Orion Nebula serves as an exceptional laboratory for investigating young and forming stars.
This cosmic region offers insights into the conditions surrounding the birth of the Sun, which occurred 4.6 billion years ago.
“Hydrogen, being the most abundant element in the universe, emits weak radio waves at a wavelength of 21 centimeters when in its neutral atomic form, enabling astronomers to track unseen gas between stars,” explained Dr. Juan Diego Soler from the University of Vienna and his team.
To achieve such detailed imaging, astronomers integrated data from the VLA and FAST observatories.
“Earlier studies indicated that the shell enveloping Orion possesses approximately 1,000 solar masses,” the researchers noted.
“New observations reveal that its mass is almost 10 times lower.”
The updated radio map also reveals a secondary expanding cavity within the main shell and a narrow “protrusion” of atomic gas extending about four light-years from the bubble.
These findings suggest that the formation of the Orion Nebula resulted from several instances of stellar feedback rather than one expansive event.
“These complexities challenge our existing understanding of star formation,” stated Dr. Daniel Seifried, an astronomer at the University of Cologne.
“Such unexpected observations are pivotal for modern astrophysical simulations that explore the evolution of gas and stars in the Milky Way.”
“These fascinating images question the theoretical models and numerical simulations we depend on to explain how massive stars interact with their environments,” Dr. Claire Murray from the Space Telescope Science Institute remarked.
“Orion is merely the beginning,” Dr. Soler emphasized.
“Our innovative method will enable future interferometers to unveil the hidden structures and dynamics of the interstellar medium, even in regions previously thought to be well understood.”
For further details, refer to the results published in the journal Astronomy and Astrophysics.
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JD Soler et al. 2026. Neutral Atomic Hydrogen Near the Sun (NeAtHood) Project. I. Ghost in the Shell: Neutral atomic hydrogen in the expanded Orion Nebula. A&A 711, A85; doi: 10.1051/0004-6361/202659272
Source: www.sci.news
