The gas clouds that give birth to stars are not visible to the naked eye. But a new three-dimensional map finally reveals these hidden regions of our Galaxy. The result of patient work, it promises to shed light on the role of the most massive stars on their environment and on star formation.
This breakthrough relies on data from the Gaia space telescope, launched by the European Space Agency in 2013. Its mission was to measure the position and brightness of over a billion stars with unparalleled precision. Researchers thus used the attenuation of light caused by interstellar dust, as well as the distances of hot O-type stars, to create the most detailed map ever obtained of these cosmic nurseries.
An unprecedented mapping of stellar nurseries
The new map covers a sphere of 4,000 light-years centered on the Sun. It is based on the analysis of 44 million ordinary stars and 87 O-type stars. These massive, rare stars, which are luminous in ultraviolet, help locate areas where hydrogen is ionized, an indicator of stellar birth.
Researchers now have a three-dimensional view of famous regions, such as the Gum Nebula, the North America Nebula, the California Nebula, and the Orion-Eridanus Superbubble. These images are no longer limited to a simple flat projection but instead reveal the volumes and internal structure of these clouds.
According to the team, the map constitutes the first model of the distribution of ionized gas that matches observations made by other instruments. It therefore provides a reliable reconstruction of what our portion of the Milky Way would look like from above.
Video of the most precise 3D map of the Milky Way's stellar nurseries What the map reveals about our Galaxy
Researchers observe that some regions appear open, allowing streams of gas and dust to escape into a vast cavity. This illustrates the action of radiation emitted by massive stars, which can reshape the surrounding space.
The study also shows how interactions between cold gas and gas heated by radiation shape the structure of our galactic neighborhood. These processes not only contribute to destroying clouds but also to creating new ones that favor star formation.
Ultimately, scientists hope to extend the mapping well beyond 4,000 light-years when future Gaia data releases become available. The next one, even richer, should allow this dive into the stellar cradles to be extended.
Article author: Cédric DEPOND