Scientists Peer Into the 3D Structure of the Milky Way and Observe Star-Forming Processes in Unprecedented Detail

Example of the clouds identified in a small section of the SEDIGISM survey.
Credit: Cardiff University

Survey of the sky pushes the boundaries of what we know about the structure of our galaxy.

Scientists from Cardiff University have helped produce a brand-new, three-dimensional survey of our galaxy, allowing them to peer into the inner structure and observe its star-forming processes in unprecedented detail.

The large-scale survey, called SEDIGISM (Structure, Excitation and Dynamics of the Inner Galactic Interstellar Medium), has revealed a wide range of structures within the Milky Way, from individual star-forming clumps to giant molecular clouds and complexes, that will allow astronomers to start pushing the boundaries of what we know about the structure of our galaxy.

SEDIGISM has been unveiled through the publication of three separate papers in the Monthly Notices of the Royal Astronomical Society, authored by an international team of over 50 astronomers.

“With the publication of this unprecedentedly detailed map of cold clouds in our Milky Way, a huge observational effort comes to fruition”, says Frederic Schuller from the Max Planck Institute for Radio Astronomy (MPIfR), lead author of one of the three publications, presenting the data release.

Dr. Ana Duarte Cabral, a Royal Society University Research Fellow from Cardiff University’s School of Physics and Astronomy, was lead author on one of the papers and has provided a catalog of over 10,000 clouds of molecular gas in our Milky Way.

The Milky Way, named after its hazy appearance from Earth, is a spiral galaxy with an estimated diameter between 170,000 and 200,000 light-years which contains between 100–400 billion stars.

The Milky Way consists of a core region that is surrounded by a warped disk of gas and dust that provides the raw materials from which new stars are formed.

For Dr. Duarte Cabral, the new catalog of gas clouds will allow scientists to probe exactly how the spiral structure of our own Milky Way affects the life cycle of clouds, their properties, and ultimately the star formation that goes on within them.

“What is most exciting about this survey is that it can really help pin down the global galactic structure of the Milky Way, providing an astounding 3D view of the inner galaxy,” she said.

“With this survey we really have the ability to start pushing the boundaries of what we know about the global effects of the galactic structures and dynamics, in the distribution of molecular gas and star formation, because of the improved sensitivity, resolution, and the 3D view.”

The catalog of molecular gas clouds was created by measuring the rare isotope of the carbon monoxide molecule, 13CO, using the extremely sensitive 12-meter Atacama Pathfinder Experiment telescope on the Chajnantor plateau in Chile.

This allowed the team to produce more precise estimates of the mass of the gas clouds and discern information about their velocity, therefore providing a truly three-dimensional picture of the galaxy.

Dr. Duarte Cabral and colleagues are already beginning to tease out information from the vast amount of data at their disposal.

“The survey revealed that only a small proportion, roughly 10%, of these clouds have dense gas with ongoing star formation,” said James Urquhart from the University of Kent, the lead author of the third publication.

MORE of the story / click image TOP of PAGE