Investigating more than 1,000 star-forming regions to understand stellar birth

In the ALMAGAL project, an international research team will analyze observations of more than a thousand “star factories” to better understand the origin and formation of new stars. Most previous studies have focused on the specific star formation in certain regions. The data from the ALMAGAL project allows researchers to analyze the full diversity of processes underlying star formation.

Stars are large balls of plasma—stellar nuclear reactors that illuminate the universe. They are formed into huge clouds of gas and dust, which collapse and break up into smaller fragments. A full understanding of this process is still elusive. The research, which analyzes data from more than 1,000 “stellar nurseries,” will contribute to solving this question. The studies are published on the arXiv preprint server.

The clouds of gas and dust from which new stars are born work like industrial factories. Simple building blocks from these clouds are used—such as hydrogen, helium and small amounts of heavier elements—to produce more complex formations such as stars and their precursors. However, the way each “factory” works and the results can be very different.

Each star-forming region can work at different speeds and with very different structures. Their products—the stars—have different masses, temperatures and compositions. These fluctuations have inspired astronomers to try to find out what precisely happens inside the factories and to explain the differences.

In order to understand the complicated and regionally different processes involved in star formation, the ALMAGAL team recorded and analyzed data from as many star factories as possible. They want to investigate the mechanisms underlying all types of star factories to uncover general “recipes” for star formation. Is it possible to generalize the study results? The analysis included detailed observations from around 1,000 star-forming regions, three to four times more than all previous studies combined.

“Now that the first analysis results are available, we can for the first time conduct statistically relevant studies to understand the many different ways stars can form and how their environment affects this process,” said Professor Dr. Peter Schilke from the University of Cologne’s Institute of Astrophysics.

“ALMAGAL provides a huge amount of data that allows us to look at large numbers of protostars in detail. This marks the beginning of a new era of precision astrophysics by analyzing their molecular fingerprints,” explained Dr. Beth Jones from the Institute of Astrophysics who is responsible for analyzing the temperatures.

ALMAGAL uses data from the international radio observatory ALMA (Atacama Large Millimeter/Submillimeter Array). ALMA is located at an altitude of 5,000 meters on Cerro Chajnantor in the Chilean Atacama Desert. It does not observe visible light, but examines the millimeter and submillimetre wavelengths that are invisible to the human eye. This makes ALMA ideal for observing cold cosmic objects such as the dust and gas of star factories, which only shine at these long wavelengths.

As ALMA also combines the light from different antennas that are many kilometers apart, it can detect very fine details. ALMA is operated by a consortium of international institutes from Europe (represented by the European Southern Observatory ESO), North America (U.S., Canada) and East Asia (Japan, Taiwan, South Korea).