Gaia delivers first 3D fly through map of star forming regions in the Milky Way
by Erica Marchand
Paris, France (SPX) Sep 25, 2025

Scientists have produced the most detailed three-dimensional map yet of stellar nurseries within our galaxy, using data from the European Space Agency's Gaia mission. The new model reveals how massive young stars interact with interstellar clouds, transforming our understanding of star-forming environments.

Studying stellar birthplaces has always been challenging, since thick gas and dust obscure them from view. Gaia cannot observe these clouds directly but measures how much starlight is blocked, enabling scientists to trace dust and associated ionised hydrogen gas. These measurements mark the regions where new stars are born.

The model incorporates data from 44 million ordinary stars and 87 rare O-type stars within 4000 light-years of the Sun. O stars are extremely hot and bright, emitting ultraviolet radiation powerful enough to ionise surrounding hydrogen gas. This interaction helps astronomers identify active stellar nurseries.

While many telescopes have mapped these regions in two dimensions, Gaia provides the first accurate reconstruction in 3D. "Gaia provides the first accurate view of what our section of the Milky Way would look like from above," said Lewis McCallum of the University of St Andrews, lead author of two studies presenting the new map.

McCallum's work reveals detailed structures of well-known regions such as the Gum Nebula, the North American Nebula, the California Nebula, and the Orion-Eridanus superbubble. The model allows scientists to virtually fly around and through these interstellar structures, offering an unprecedented view of how gas and dust are shaped by stellar radiation.

Researchers have already identified evidence of ruptures in star-forming clouds, with gas and dust venting into a larger galactic cavity. "This map nicely shows how radiation of massive stars ionises the surrounding interstellar medium and how dust and gas interact with this radiation," noted Sasha Zeegers, ESA Research Fellow.

The project required massive computational resources to generate the high-resolution 3D maps. Future Gaia data releases are expected to extend coverage beyond the current 4000 light-year limit, providing even deeper insights into how stars and stellar clusters evolve.

"Gaia's distance measurements of the nearby hot stars, and the 3D maps of dust - obtained from measuring the extinction and positions of millions of ordinary stars using Gaia data - are both crucial ingredients of this new map," added Johannes Sahlmann, ESA Gaia Project Scientist.

Research Report:A three-dimensional, multiwavelength view and time-dependent analysis of the Milky Way's local ionized gas

Related Links
Gaia's sky maps
Stellar Chemistry, The Universe And All Within It